Mildly amusing, but it seems like this is thinking that two wrongs make a right, so let us serve malware instead of using a WAF or some other existing solution to the bot problem.
That's why I said, if it's easy. On some server stacks it's no big deal to have a connection open for an extra 30 seconds; others, you need to be done with requests asap, even abuse.
tcpdrop shouldn't self DOS though, it's using less resources. Even if other end does a retry, it will do it after a timeout; in the meantime, the other end has a socket state and you don't, that's a win.
So first, let me prefix this by saying I generally don't accept cookies from websites I don't explicitly first allow, my reasoning being "why am I granting disk read/write access to [mostly] shady actors to allow them to track me?"
(I don't think your blog qualifies as shady … but you're not in my allowlist, either.)
So if I visit https://anubis.techaro.lol/ (from the "Anubis" link), I get an infinite anime cat girl refresh loop — which honestly isn't the worst thing ever?
Neither xeserv.us nor techaro.lol are in my allowlist. Curious that one seems to pass. IDK.
The blog post does have that lovely graph … but I suspect I'll loop around the "no cookie" loop in it, so the infinite cat girls are somewhat expected.
I was working on an extension that would store cookies very ephemerally for the more malicious instances of this, but I think its design would work here too. (In-RAM cookie jar, burns them after, say, 30s. Persisted long enough to load the page.)
Just FYI temporary containers (Firefox extension) seem to be the solution you're looking for. It essentially generates a new container for every tab you open (subtabs can be either new containers or in the same container). Once the tab is closed it destroys the container and deletes all browsing data (including cookies). You can still whitelist some domains to specific persistent containers.
I used cookie blockers for a long time, but always ended up having to whitelist some sites even though I didn't want their cookies because the site would misbehave without them. Now I just stopped worrying.
At least, not with the default rules. I read that discussion a few days ago and was surprised how few callouts there were that a WAF is just a part of the infrastructure - it is the rules that people are actually complaining about. I think the problem is that so many apps run on AWS and their default WAF rules have some silly content filtering. And their "security baseline" says that you have to use a WAF and include their default rules, so security teams lock down on those rules without any real thought put into whether or not they make sense for any given scenario.
I admire your deontological zealotry. That said, I think there is an implied virtuous aspect of "internet vigilantism" that feels ignored (i.e. disabling a malicious bot means it does not visit other sites) While I do not absolve anyone from taking full responsibility for their actions, I have a suspicion that terrorists do a bit more than just avert a greater wrong--otherwise, please sign me up!
The web is overrun by malicious actors without any sense of morality. Since playing by the rules is clearly not working, I'm in favor of doing anything in my power to waste their resources. I would go a step further and try to corrupt their devices so that they're unable to continue their abuse, but since that would require considerably more effort from my part, a zip bomb is a good low-effort solution.
Based on the example in the post, that thinking might need to be extended to "someone happening to be using a blocklisted IP." I don't serve up zip bombs, but I've blocklisted many abusive bots using VPN IPs over the years which have then impeded legitimate users of the same VPNs.
I think that's the point, you'd use robots.txt to direct Googlebot/Bingbot/etc away from countermeasures that could potentially mess up your SEO. If other bots ignore the signpost clearly saying not to enter the tarpit, that's their own stupid fault.
I also had the idea of zip bomb to confuse badly behaved scrapers (and I have mentioned it before to some other people, although I did not implemented it). However, maybe instead of 0x00, you might use a different byte value.
I had other ideas too, but I don't know how well some of them will work (they might depend on what bots they are).
I meant that all of the byte values would be the same (so they would still be repeating), but a different value than zero. However, Brotli could be another idea if the client supports it.
Compressing a sequence of any single character should give almost identical results length-wise (perhaps not exactly identical, but the difference will be vanishingly small).
I protected uploads on one of my applications by creating fixed size temporary disk partitions of like 10MB each and unzipping to those contains the fallout if someone uploads something too big.
2048 yottabyte Zip Bomb
This zip bomb uses overlapping files and recursion to achieve 7 layers with 256 files each, with the last being a 32GB file.
It is only 266 KB on disk.
When you realise it's a zip bomb it's already too late. Looking at the file size doesn't betray its contents. Maybe applying some heuristics with ClamAV? But even then it's not guaranteed. I think a small partition to isolate decompression is actually really smart. Wonder if we can achieve the same with overlays.
What are you talking about? You get a compressed file. You start decompressing it. When the amount of bytes you've written exceeds some threshold (say 5 megabytes) just stop decompressing, discard the output so far & delete the original file. That is it.
Those files are designed to exhaust the system resources before you can even do these kinds of checks. I'm not particularly familiar with the ins and outs of compression algorithms, but it's intuitively not strange for me to have a a zip that is carefully crafted so that memory and CPU goes out the window before any check can be done. Maybe someone with more experience can give mode details.
I'm sure though that if it was as simples as that we wouldn't even have a name for it.
Not really. It really is that simple. It's just dictionary decompression, and it's just halting it at some limit.
It's just nobody usually implements a limit during decompression because people aren't usually giving you zip bombs. And sometimes you really do want to decompress ginormous files, so limits aren't built in by default.
Your given language might not make it easy to do, but you should pretty much always be able to hack something together using file streams. It's just an extra step is all.
I honestly thought it was harder. It's still a burden on the developer to use the tools in the intended way so that the application isn't vulnerable, so it's something to keep in mind when implementing functionality that requires unpacking user provided compressed archives.
> it's intuitively not strange for me to have a a zip that is carefully crafted so that memory and CPU goes out the window before any check can be done
It's intuitively extremely strange to me!
Even ignoring how zips work: Memory needs to be allocated in chunks. So before allocating a chunk, you can check if the new memory use will be over a threshold. CPU is used by the program instructions you control, so you can put checks at significant points in your program to see if it hit a threshold. Or you can have a thread you kill after a certain amount of time.
But the way zips do work makes it a lot simpler: Fundamentally it's "output X raw bytes, then repeat Y bytes from location Z" over and over. Abort if those numbers get too big.
That assumes they're using a stream decompressor library and are feeding that stream manually. Solutions that write the received file to $TMP and just run an external tool (or, say, use sendfile()) don't have the option to abort after N decompressed bytes.
> Solutions that write the received file to $TMP and just run an external tool (or, say, use sendfile()) don't have the option to abort after N decompressed bytes
cgroups with hard-limits will let the external tool's process crash without taking down the script or system along with it.
> That assumes they're using a stream decompressor library and are feeding that stream manually. Solutions that write the received file to $TMP and just run an external tool (or, say, use sendfile()) don't have the option to abort after N decompressed bytes.
In a practical sense, how's that different from creating a N-byte partition and letting the OS return ENOSPC to you?
Depending on the language/library that might not always be possible. For instance python's zip library only provides an extract function, without a way to hook into the decompression process, or limit how much can be written out. Sure, you can probably fork the library to add in the checks yourself, but from a maintainability perspective it might be less work to do with the partition solution.
It also provides an open function for the files in a zip file. I see no reason something like this won't bail after a small limit:
import zipfile
with zipfile.ZipFile("zipbomb.zip") as zip:
for name in zip.namelist():
print("working on " + name)
left = 1000000
with open("dest_" + name, "wb") as fdest, zip.open(name) as fsrc:
while True:
block = fsrc.read(1000)
if len(block) == 0:
break
fdest.write(block)
left -= len(block)
if left <= 0:
print("too much data!")
break
No, compression formats are not Turing-complete. You control the code interpreting the compressed stream and allocating the memory, writing the output, etc. based on what it sees there and can simply choose to return an error after writing N bytes.
Not really. It's easy to abort after exceeding a number of uncompressed bytes or files written. The problem is the typical software for handling these files does not implement restrictions to prevent this.
I worked on a commercial HTTP proxy that scanned compressed files. Back then we would start to decompress a file but keep track of the compression ratio. I forget what the cutoff was but as soon as we saw a ratio over a certain threshold we would just mark the file as malicious and block it.
Seems like a good and simple strategy to me. No real partition needed; tmpfs is cheap on Linux. Maybe OP is using tools that do not easily allow tracking the number of uncompressed bytes.
I'd put fake paper namers (doi.numbers.whatever.zip) in order to quickly keep their attention, among a robots.txt file for a /papers subdirectory to 'disallow' it. Add some index.html with links to fake 'papers' and in a week these crawlers will blacklist your like crazy.
Doesn't deal with multi-file ZIP archives. And before you think you can just reject user uploads with multi-file ZIP archives, remember that macOS ZIP files contain the __MACOSX folder with ._ files.
I sort of did this with ssh where I figured out how to crash an ssh client that was trying to guess the root password. What I got for my trouble was a number of script kiddies ddosing my poor little server. I switched to just identifying 'bad actors' who are clearly trying to do bad things and just banning their IP with firewall rules. That's becoming more challenging with IPV6 though.
Edit: And for folks who write their own web pages, you can always create zip bombs that are links on a web page that don't show up for humans (white text on white background with no highlight on hover/click anchors). Bots download those things to have a look (so do crawlers and AI scrapers)
You probably want to check how many ips/blocks a provider announces before blocking the entire thing.
It's also not a common metric you can filter on in open firewalls since you must lookup and maintain a cache of IP to ASN, which has to be evicted and updated as blocks still move around.
true, but you can make the link text 'do not click this' or 'not a real link' to let them know. I'm not sure if crawlers have started using LLMs to check pages or not which would be a problem.
Weird that text browsers just ignore all the attributes that hide elements. I get that they don't care about styling, but even a plain hidden attribute or aria-hidden are ignored.
> you can always create zip bombs that are links on a web page that don't show up for humans
I did a version of this with my form for requesting an account on my fediverse server. The problem I was having is that there exist these very unsophisticated bots that crawl the web and submit their very unsophisticated spam into every form they see that looks like it might publish it somewhere.
First I added a simple captcha with distorted characters. This did stop many of the bots, but not all of them. Then, after reading the server log, I noticed that they only make three requests in a rapid succession: the page that contains the form, the captcha image, and then the POST request with the form data. They don't load neither the CSS nor the JS.
So I added several more fields to the form and hid them with CSS. Submitting anything in these fields will fail the request and ban your session. I also modified the captcha, I made the image itself a CSS background, and made the src point to a transparent image instead.
And just like that, spam has completely stopped, while real users noticed nothing.
If CSS is disabled or using a browser that does not implement CSS, that might also be an issue. (A mode to disable CSS should ideally also be able to handle ARIA attributes (unless the user disables those too), but not all implementations will do this (actually, I don't know if any implementation does; it doesn't seem to on mine), especially if they were written before ARIA attributes were invented.)
Automated systems like Cloudflare and stuff also have a list of bot IPs. I was recently setting up a selfhosted VPN and I had to change the IPv4 of the server like 20 times before I got an IP that wasn't banned on half the websites.
> you can always create zip bombs that are links on a web page that don't show up for humans (white text on white background with no highlight on hover/click anchors)
> I sort of did this with ssh where I figured out how to crash an ssh client that was trying to guess the root password. What I got for my trouble was a number of script kiddies ddosing my poor little server.
This is the main reason I haven't installed zip bombs on my website already -- on the off chance I'd make someone angry and end up having to fend off a DDoS.
Currently I have some URL patterns to which I'll return 418 with no content, just to save network / processing time (since if a real user encounters a 404 legitimately, I want it to have a nice webpage for them to look at).
Should probably figure out how to wire that into fail2ban or something, but not a priority at the moment.
I am ignorant as to how most bots work. Could you have a second line of defense for bots that avoid this bomb: Dynamically generate a file from /dev/random and trickle stream it to them, or would they just keep spawning parallel requests? They would never finish streaming it, and presumably give up at some point. The idea would be to make it more difficult for them to detect it was never going to be valid content.
If the bot is connecting over IPv4, you only have a couple thousand connections before your server starts needing to mess with shared sockets and other annoying connectivity tricks.
I don't think it's a terrible problem to solve these days, especially if you use one of the tarpitting implementations that use nftables/iptables/eBPF, but if you have one of those annoying Chinese bot farms with thousands of IP addresses hitting your server in turn (Huawei likes to do this), you may need to think twice before deploying this solution.
You want to consider the ratio of your resource consumption to their resource consumption. If you trickle bytes from /dev/random, you are holding open a TCP connection with some minimal overhead, and that's about what they are doing too. Let's assume they are bright enough to use any of the many modern languages or frameworks that can easily handle 10K/100K connections or more on a modern system. They aren't all that bright but certainly some are. You're basically consuming your resources to their resources 1:1. That's not a winning scenario for you.
The gzip bomb means you serve 10MB but they try to consume vast quantities of RAM on their end and likely crash. Much better ratio.
As mentioned, not really an issue on a modern system. But in any case, you could just read, say, 1K from /dev/urandom into a buffer and then keep resending that buffer over and over again?
That's clear. It all comes down to their behavior. Will they sit there waiting to finish this download, or just start sending other requests in parallel until you dos yourself? My hope is they would flag the site as low-value and go looking elsewhere, on another site.
For HTTP/1.1 you could send a "chunked" response. Chunked responses are intended to allow the server to start sending dynamically generated content immediately instead of waiting for the generation process to finish before sending. You could just continue to send chunks until the client gives up or crashes.
There's a lot of creative ideas out there for banning and/or harassing bots. There's tarpits, infinite labyrinths, proof of work || regular challenges, honeypots etc.
Most of the bots I've come across are fairly dumb however, and those are pretty easy to detect & block. I usually use CrowdSec (https://www.crowdsec.net/), and with it you also get to ban the IPs that misbehave on all the other servers that use it before they come to yours. I've also tried turnstile for web pages (https://www.cloudflare.com/application-services/products/tur...) and it seems to work, though I imagine most such products would, as again most bots tend to be fairly dumb.
I'd personally hesitate to do something like serving a zip bomb since it would probably cost the bot farm(s) less than it would cost me, and just banning the IP I feel would serve me better than trying to play with it, especially if I know it's misbehaving.
Edit: Of course, the author could state that the satisfaction of seeing an IP 'go quiet' for a bit is priceless - no arguing against that
It's worth noting that this is a gzip bomb (acts just like a normal compressed webpage), not a classical zip file that uses nested zips to knock out antiviruses.
"On 21 September 1997, the USS Yorktown halted for almost three hours during training maneuvers off the coast of Cape Charles, Virginia due to a divide-by-zero error in a database application that propagated throughout the ship’s control systems."
" technician tried to digitally calibrate and reset the fuel valve by entering a 0 value for one of the valve’s component properties into the SMCS Remote Database Manager (RDM)"
I had a ton of trouble opening a 10MB or so png a few weeks back. It was stitched together screenshots forming a map of some areas in a game, so it was quite large. Some stuff refused to open it at all as if the file was invalid, some would hang for minutes, some opened blurry. My first semi-success was Fossify Gallery on my phone from F-Droid. If I let it chug a bit, it'd show a blurry image, a while longer it'd focus. Then I'd try to zoom or pan and it'd blur for ages again. I guess it was aggressively lazy-loading. What worked in the end was GIMP. I had the thought that the image was probably made in an editor, so surely an editor could open it. The catch is that it took like 8GB of RAM, but then I could see clearly, zoom, and pan all I wanted. It made me wonder why there's not an image viewer that's just the viewer part of GIMP or something.
Among things that didn't work were qutebrowser, icecat, nsxiv, feh, imv, mpv. I did worry at first the file was corrupt, I was redownloading it, comparing hashes with a friend, etc. Makes for an interesting benchmark, I guess.
That's a 36,000x20,000 PNG, 720 megapixels. Many decoders explicitly limit the maximum image area they'll handle, under the reasonable assumption that it will exceed available RAM and take too long, and assume the file was crafted maliciously or by mistake.
Safari on my MacBook Air opened it fine, though it took about four seconds. Zooming works fine as well. It does take ~3GB of memory according to Activity Monitor.
For what it's worth, this loaded (slowly) in Firefox on Windows for me (but zooming was blurry), and the default Photos viewer opened it no problem with smooth zooming and panning.
On Firefox on Android on my pretty old phone, a blurry preview rendered in about 10 seconds, and it was fully rendered in 20 something seconds. Smooth panning and zooming the entire time
Following up with Firefox on S24 Ultra loaded from blank to image in a second and then could zoom right in fine with no blurriness or stuttering at all!
How strange, took at least 30s to load on my iPhone 12 Pro Max with Safari but it was smooth to pan and zoom after. Which is way better than my 16 core 64GB RAM Windows machine where both Chrome and Edge gave up very quickly, with a "broken thumbnail" icon.
The strangeness was that 2 iPhones from the same generation would exhibit such different performance behaviors, and in parallel the irony that a desktop browser (engine irrelevant) on a device with cutting edge performance can't do what a phone does.
Same, right up until I zoomed in and waited for Safari to produce a higher resolution render.
Partially zoomed in was fine, but zooming to maximum fidelity resulted in the tab crashing (it was completely responsive until the crash). Looks like Safari does some pretty smart progressive rendering, but forcing it to render the image at full resolution (by zooming in) causes the render to get OOMed or similar.
Firefox on a mid-tier Samsung and a cheapo data connection (4G) took avout 30s to load. I could pan, but it limited me from zooming much, and the little I could zoom in looked quite blury.
Just today collegue was looking at some air traffic permit map within PDF that was like 12MB or something around that. Complained about Adobe Reader changing something so he cannot pan/zoom no more.
I suggested to try the HN beloved Sumatra PDF. Ugh, it couldn't cope with it normally. Chrome did it better coped better.
On my Waterfox 6.5.6, it opened but remained blurry when zoomed in.
MS Paint refused to open it.
The GIMP v2.99.18 crashed and took my display driver with it.
Windows 10 Photo Viewer surprisingly managed to open it and keep it sharp when zoomed in.
The GIMP v3.0.2 (latest version at the time of writing) crashed.
Loads fine and fairly quickly on a Macbook Pro M3 Pro with Firefox 137. Does have a bit of delay when initially zooming in, but pans and zooms fine after.
I wonder if I could create a 500TB html file with proper headers on a squashfs, an endless <div><div><div>... with no closing tags, and if I could instruct the server to not report file size before download.
Yes, servers can respond without specifying the size by using chunked encoding. And you can do the rest with a custom web server that just handles request by returning "<div>" in a loop. I have no idea if browsers are vulnerable to such a thing.
the problem with this is that for a tarpit, you just don't want to make it expensive for bots, you also want to make it cheap for yourself. this isn't cheap for you. a zip bomb is.
maybe, maybe not. it's one tool at your disposal. it's easy to guard against zip bombs if you know about them - the question is, how thorough are the bot devs you're targeting?
there are other techniques. for example: hold a connection open and only push out a few bytes every few seconds - whether that's cheap for you or not depends on your servers concurrency model (if it's 1 OS thread per connection, then you'd DOS yourself with this - but with an evented model you should be good). if the bot analyzes images or pdfs you could try toxic files that exploit known weaknesses which lead to memory corruption to crash them; depends on the bots capabilities and used libraries of course.
I just tested it via a small python script sending divs at a rate of ~900mb (as measured by curl) and firefox just kills the request after 1-2 gb received (~2 seconds) with an "out of memory" error, while chrome seems to only receive around 1mb/s, uses 1 cpu core 100%, and grows infinitely in memory use. I killed it after 3 mins and consuming ca. 6GB (additionally, on top of the memory it used at startup)
Why use squashfs when you can do the same OP did and serve a compressed version, so that the client is overwhelmed by both the uncompression and the DOM depth:
I am not sure how that could’ve worked. Unless the real /dev tree was exposed to your webserver’s chroot environment, this would’ve given nothing special except “file not found”.
The whole point of chroot for a webserver was to shield clients from accessing special files like that!
This does not logically follow. If your bot is getting slammed by a page returning all zeros (what the person I replied to reacted to), all you know is something on the server is returning a neverending stream of zeros. A symlink to /dev/zero is an easy way of doing that, but knowing the server is serving up a neverending stream of zeros by no means tells you whether the server is running in a decently isolated environment or not.
Even if you knew it was done with a symlink you don't know that - these days odds are it'd run in a container or vm, and so having access to /dev/zero means very little.
I guess it depends on the server's implementation. but, since you need some logic to decide when to serve the html bomb anyway, I don't see why you would prefer this solution. Just use whatever script you're using to detect the bots to serve the bomb.
Well creating a bot is not per se illegal, so assuming the maliciousness-detector on the server isn’t perfect, it could serve the zip bomb to a legitimate bot. And I don’t think it’s crazy that serving zip bombs with the stated intent to sabotage the client would be illegal. But I’m not a lawyer, of course.
Disclosure, I'm not a lawyer either. This is all hypothetical high level discussion here.
> it could serve the zip bomb to a legitimate bot.
Can you define the difference between a legitimate bot, and a non legitimate bot for me ?
The OP didn't mention it, but if we can assume they have SOME form of robots.txt (safe assumtion given their history), would those bots who ignored the robots be considered legitimate/non-legitimate ?
Almost final question, and I know we're not lawyers here, but is there any precedent in case law or anywhere, which defines a 'bad bot' in the eyes of the law ?
Final final question, as a bot, do you believe you have a right or a privilege to scrape a website ?
> Can you define the difference between a legitimate bot, and a non legitimate bot for me ?
Well by default every bot is legitimate, an illegitimate bot might be one that’s probing for security vulnerabilities (but I’m not even sure if that’s illegal if you don’t damage the server as a side effect, ie if you only try to determine the Wordpress or SSHD version running on the server for example).
> The OP didn't mention it, but if we can assume they have SOME form of robots.txt (safe assumtion given their history), would those bots who ignored the robots be considered legitimate/non-legitimate ?
robots.txt isn’t legally binding so I don’t think ignoring it makes a bot illegitimate.
> Almost final question, and I know we're not lawyers here, but is there any precedent in case law or anywhere, which defines a 'bad bot' in the eyes of the law ?
There might be but I don’t know any.
> Final final question, as a bot, do you believe you have a right or a privilege to scrape a website ?
Well I’m not a bot but I think I have the right to build bots to scrape websites (and not get served malicious content designed to sabotage my computer). You can decline service and just serve error pages of course if you don’t like my bot.
Mantrapping is a fairly good analogy, and that's very illegal. If the person reading your gas meter gets caught in your mantrap, you're going to prison. You're probably going to prison if somebody burglarizing you gets caught in your mantrap.
Of course their computers will live, but if you accidentally take down your own ISP or maybe some third-party service that you use for something, I'd think they would sue you.
I’m not sure that’s enough, robots.txt isn’t really legally binding so if the zip bomb somehow would be illegal, guarding it behind a robots.txt rule probably wouldn’t make it fine.
Has any similar case been tried? I'd think that a judge learning the intent of robots.txt and disallow rules is fairly likely to be sympathetic. Seems like it could go either way, I mean. (Jury is probably more a crap-shoot.)
> can make an easy case to the jury that it is a booby trap to defend against trespassers
I don't know of any online cases, but the law in many (most?) places certainly tends to look unfavourably on physical booby-traps. Even in the US states with full-on “stand your ground” legislation and the UK where common law allows for all “reasonable force” in self-defence, booby-traps are usually not considered self-defence or standing ground. Essentially if it can go off automatically rather than being actioned by a person in a defensive action, it isn't self-defence.
> Who […] is going to prosecute/sue the server owner?
Likely none of them. They might though take tit-for-tat action and pull that zipbomb repeatedly to eat your bandwidth, and they likely have more and much cheaper bandwidth than your little site. Best have some technical defences ready for that, as you aren't going to sue them either: they are probably running from a completely different legal jurisdiction and/or the attack will come from a botnet with little or no evidence trail wrt who kicked it off.
The illegality of boobytrapping your house appears to be illegal because of the potential threat to life/health. A zip bomb doesn’t threaten any people. At worst, it can fill up memory and storage on a device. I’m pretty sure it wouldn’t violate any of the same statutes and it most likely wouldn’t fall nicely under any of the common law jurisprudence that you mentioned.
> pull that zipbomb repeatedly to eat your bandwidth, and they likely have more and much cheaper bandwidth than your little site.
Go read what a zip bomb is. There is one that is only a few KB, which is comparable in server load + bandwidth to a robots.txt.
No need to be a dick. Especially when you yourself are in the process of not understanding what others are saying.
I know full well what a zipbomb is. A large compressed file still has some size even in compressed form (without nesting, 1G of minimal entropy data is ~1M gzipped). If someone has noticed your bomb and worked around it by implementing relevant checks (or isn't really affected by it because of already having had those checks in place), they can get a little revenge by soaking up your bandwidth downloading it many times. OK, so nested that comes down to a few Kb, they can still throw a botnet at that, or some other content on your site, and cause you some faf, if they wish to engage in tit-for-tat action. Also: nesting doesn't work when you are using HTTP transport compression as your delivery mechanism, which is what is being discussed here: “standard” libraries supporting compressed HTTP encodings don't generally unpack nested content. There is no “Accept-Encoding: gzip+gzip” or similar.
Most, perhaps the vast majority, won't care to make the effort, so this could be considered a hypothetical, but some might. There were certainly cases, way back in my earlier days online, of junk mailers and address scrapers deliberately wasting bandwidth of sites that encouraged the use of tools like FormFucker or implemented scraper sinkholes.
Neither is the HTTP specification. Nothing is stopping you from running a Gopher server on TCP port 80, should you get into trouble if it happens to crash a particular crawler?
Making a HTTP request on a random server is like uttering a sentence to a random person in a city: some can be helpful, some may tell you to piss off and some might shank you. If you don't like the latter, then maybe don't go around screaming nonsense loudly to strangers in an unmarked area.
The law might stop you from sending specific responses if the only goal is to sabotage the requesting computer. I’m not 100% familiar with US law but I think intentionally sabotaging a computer system would be illegal.
No, why would they? If I voluntarily request your website, you can’t just reply with a virus that wipes my harddrive. Even though I had the option to not send the request. I didn’t know that you were going to sabotage me before I made the request.
Because you requested it? There is no agreement on what or how to serve things, other than standards (your browser expects a valid document on the other side etc).
I just assumed court might say there is a difference between you requesting all guess-able endpoints and find 1 endpoint which will harm your computer (while there was _zero_ reason for you to access that page) and someone putting zipbomb into index.html to intentionally harm everyone.
So serving a document exploiting a browser zero day for RCE under a URL that’s discoverable by crawling (because another page links to it) with the intent to harm the client (by deleting local files for example) would be legitimate because the client made a request? That’s ridiculous.
That is not the case in this context. robots.txt is the only thing that specifies the document URL, which it does so in a "disallow" rule. The argument that they did not know the request would be responded to with hostility could be moot in that context (possibly because a "reasonable person" would have chosen not to request the disallowed document but I'm not really familiar with when that language applies).
> by deleting local files for example
This is a qualitatively different example than a zip bomb, as it is clearly destructive in a way that a zip bomb is not. True that a zip bomb could cause damage to a system but it's not a guarantee, while deleting files is necessarily damaging. Worse outcomes from a zip bomb might result in damages worthy of a lawsuit but the presumed intent (and ostensible result) of a zip bomb is to effectively cause the recipient machine to involuntarily shut down, which a court may or may not see as legitimate given the surrounding context.
> knowingly causes the transmission of a program, information, code, or command, and as a result of such conduct, intentionally causes damage without authorization, to a protected computer;
As far as I can tell (again, IANAL) there isn't an exception if you believe said computer is actively attempting to abuse your system[2]. I'm not sure if a zip bomb would constitute intentional damage, but it is at least close enough to the line that I wouldn't feel comfortable risking it.
I don't believe the client counts as a protected computer because they initiated the connection. Also a protected computer is a very specific definition that involves banking and/or commerce and/or the government.
Part B of the definition of "protected computer" says:
> which is used in or affecting interstate or foreign commerce or communication, including a computer located outside the United States that is used in a manner that affects interstate or foreign commerce or communication of the United States
Assuming the server is running in the states, I think that would apply unless the client is in the same state as the server, in which case there is probably similar state law that comes into affect. I don't see anything there that excludes a client, and that makes sense, because otherwise it wouldn't prohibit having a site that tricks people into downloading malware.
The word "accessed" is used multiple times throughout the law. A client accesses a server. A server does not access a client. It responds to a client.
Also, the protected computer has to be involved in commerce. Unless they are accessing the website with the zip bomb using a computer that also is uses for interstate or foreign commerce, it won't qualify.
> The word "accessed" is used multiple times throughout the law.
So what? It isn't in the section I quoted above. I could be wrong, but my reading is that transmitting information that can cause damage with the intent of causing damage is a violation, regardless of if you "access" another system.
> Also, the protected computer has to be involved in commerce
Or communication.
Now, from an ethics standpoint, I don't think there is anything wrong with returning a zipbomb to malicious bots. But I'm not confident enough that doing so is legal that I would risk doing so.
> So what? It isn't in the section I quoted above.
You can't read laws in sections like that. They sections go together. The entire law is about causing damage through malicious access. But servers don't access clients.
The section you quoted isn't relevant because the entire law is about clients accessing servers, not servers responding to clients.
Every reference to access I see in that law is in a separate item in the list of violations in section 1. Where do you see something that would imply that section 5a only applies to clients accessing servers?
> The Commerce Clause is the source of federal drug prohibition laws under the Controlled Substances Act. In a 2005 medical marijuana case, Gonzales v. Raich, the U.S. Supreme Court rejected the argument that the ban on growing medical marijuana for personal use exceeded the powers of Congress under the Commerce Clause. Even if no goods were sold or transported across state lines, the Court found that there could be an indirect effect on interstate commerce and relied heavily on a New Deal case, Wickard v. Filburn, which held that the government may regulate personal cultivation and consumption of crops because the aggregate effect of individual consumption could have an indirect effect on interstate commerce.
A protected computer is "a computer which is protected by this law", which is most American computers, not a special class of American computers. The only reason it's not all American computers is that the US federal government doesn't have full jurisdiction over the US. They wrote the definition of "protected computer" to include all the computers they have jurisdiction over.
In particular, the interstate commerce clause is very over-reaching. It's been ruled that someone who grew their own crops to feed to their own farm animals sold locally was conducting interstate commerce because they didn't have to buy them from another state.
There is IMO no legal use case for an external computer system to initiate a connection with my system without prior legal agreement. It all happens on good will.
There is IMO no legal use case for an external computer system to initiate a connection with my system without prior legal agreement. It all happens on good will and therefore can be terminated at any time.
So the trick is to disguise it as an accident. Have the zip bomb look like a real HTML file at the beginning, then have zeroes after that, like it got corrupted.
well, what does "damage" mean in that law? filling the disk isn't destructive. filling RAM isn't destructive. there's nothing in a zip-bomb approach that is destructive; a reboot or an `rm` (at most) undoes it all. I would say that this doesn't qualify as a destructive operation in any way.
Just put a "by connecting to this service, you agree to and authorize…" at the front of the zipbomb.
(I'm half-joking, half-crying. It's how everything else works, basically. Why would it not work here? You could even go as far as explicitly calling it a "zipbomb test delivery service". It's not your fault those bots have no understanding what they're connecting to…)
Just crossed my mind that perhaps lots of bot traffic is coming from botnets of unaware victims who downloaded a shitty game or similar, orchestrated by a malicious C&C server somewhere else. (There was a post about this type of malware recently.) Now, if you crash the victims machine, it’s complicated at least ethically, if not legally.
The blog runs on a $6 digital ocean droplet. It's 1GB RAM and 25GB storage. There is a link at the end of the article on how it handles typical HN traffic. Currently at 5% CPU.
> At my old employer, a bot discovered a wordpress vulnerability and inserted a malicious script into our server
I know it's slightly off topic, but it's just so amusing (edit: reassuring) to know I'm not the only one who, after 1 hour of setting up Wordpress there's a PHP shell magically deployed on my server.
There's a lot of essential functionality missing from WordPress, meaning you have to install plugins. Depending on what you need to do.
But it's such a bad platform that there really isn't any reason for anybody to use WordPress for anything. No matter your use case, there will be a better alternative to WordPress.
Can you recommend an alternative for a non-technical organization, where there's someone who needs to be able to edit pages and upload documents on a regular basis, so they need as user-friendly an interface as possible for that? Especially when they don't have a budget for it, and you're helping them out as a favor? It's so easy to spin up Wordpress for them, but I'm not a fan either.
I've tried Drupal in the past for such situations, but it was too complicated for them. That was years ago, so maybe it's better now.
> Can you recommend an alternative for a non-technical organization, where there's someone who needs to be able to edit pages and upload documents on a regular basis, so they need as user-friendly an interface as possible for that
25 years ago we used Microsoft Frontpage for that, with the web root mapped to a file share that the non-technical secretary could write to and edit it as if it were a word processor.
Somehow I feel we have regressed from that simplicity, with nothing but hand waving to make up for it. This method was declared "obsolete" and ... Wordpress kludges took its place as somehow "better". Someone prove me wrong.
I think you're mistaken. The use of WebDAV was not a requirement. Frontpage could function in "HTML editor" mode and just write to the filesystem. In that case, any WYSIWYG editor would do but FP was there and available.
For those on macOS, RapidWeaver still exists: https://www.realmacsoftware.com/rapidweaver/. (Shame that it's now subscriptionware, though – could've sworn it used to be an outright purchase per major version.)
Jekyll and other static site generators do not repo Wordpress any more than notepad repos MSWord
In one, multiple users can login, edit WYSIWYG, preview, add images, etc, all from one UI. You can access it from any browser including smart phones and tablets.
In the other, you get to instruct users on git, how to deal with merge conflicts, code review (two people can't easily work on a post like they can in wordpress), previews require a manual build, you need a local checkout and local build installation to do the build. There no WYSIWYG, adding images is a manual process of copying a file, figuring out the URL, etc... No smartphone/tablet support. etc....
I switched by blog from wordpress install to a static site geneator because I got tired of having to keep it up to date but my posting dropped because of friction of posting went way up. I could no longer post from a phone. I couldn't easily add images. I had to build to preview. And had to submit via git commits and pushes. All of that meant what was easy became tedious.
what are your favorite static site generators? I googled it and cloudflare article came up with Jekyll,Gatsby,Hugo,Next.js, Eleventy. But would like to avoid doing research if can be helped on pros/cons of each.
I don’t have much experience with other SSGs, but I’ve been using Eleventy for my personal site for a few years and I’m a big fan. It’s very simple to get started with, it’s fast to build, it’s powerful and flexible.
I build mine with GitHub Actions and host it free on Pages.
I looked recently when thinking of starting some new shared blog. My criteria was "based on tech I know". I don't know Ruby so Jekyll was out. I tried Eleventy and Hexo. I chose Hexo but then ultimately decided I wasn't going to do this new blog.
IIRC, Eleventy printed lots of out-of-date warnings when I installed it and/or the default style was broken in various ways which didn't give me much confidence.
My younger sister asked me to help her start a blog. I just pointed her to substack. Zero effort, easy for her.
I work with Ruby but I never had to use Ruby to use Jekyll. I downloaded the docker image and run it. It checks a host directory for updates and generates the HTML files. It could be written in any other language I don't know.
Yes I can. There's an excellent and stable solution called SurrealCMS, made by an indie developer. You connect it by FTP to any traditional web design (HTML+CSS+JS), and the users get a WYSIWYG editor where the published output looks exactly as it looked when editing. It's dirt cheap at $9 per month.
Edit: I actually feel a bit sorry for the SurrealCMS developer. He has a fantastic product that should be an industry standard, but it's fairly unknown.
Drupal has been around for a while, but I've never heard of "Drupal CMS" as a separate product until now.
It appears Drupal CMS is a customized version of Drupal that is easier for less tech-savvy folks to get up and running. At least, that's the impression I got reading through the marketing hype that "explains" it with nothing but buzzwords.
YES! I have switched to it for professional and personal CMS work and it's great. Incredibly flexible and simplistic in my opinion. I use it both as headful and headless.
I find it very telling that there's no 2 responses to this post recommending the same thing. Confirms my belief that there is no real alternative to Wordpress for a free and open-source CMS that is straightforward to install and usable to build and edit pages by non-tech-experts.
We have a (internally accessible only) WP instance where the content is exported using a plugin as a ZIP file and then deployed to NGINX servers with a bit of scripting/Ansible.
Could be automated better (drop ZIP to a share somewhere where it gets processed and deployed) but best of both worlds.
I do custom web dev so am way out of the website hosting game. What are good frameworks now if I want to say, light touch help someone who is slightly technical set up a website? Not full react SPA with an API.
By the sound of your question I will guess you want to make a website for a small or medium sized organization? jQuery is probably the only "framework" you should need.
If they are selling anything on their website, it's probably going to be through a cloud hosted third party service and then it's just an embedded iframe on their website.
If you're making an entire web shop for a very large enterprise or something of similar magnitude, then you have to ask somebody else than me.
jQuery's still the third most used web framework, behind React and before NextJS. If you use jQuery to build Wordpress websites, you'd be specializing in popular web technologies in the year 2025.
I've seen this site linked for many years among web devs, but I just don't understand the purpose? jQuery code is much cleaner and easier to understand, and there's a great amount of solutions written for jQuery available online for almost any need you have.
Just not true, although entirely aligned with HN users who often believe that the levels of nerdery on HN are common in the real world. WP isn’t bad, you’ve just done it wrong, and there really isn’t a better alternative for hundreds and hundreds of use cases..
My perspective is that WordPress is too complicated and too nerdy for most real world users. They are usually better off with a solution that is tailor made for their use case. And there's plenty of such solutions. Even for blogging, there are much better solutions than WordPress for non-technical users.
Totally disagree! If you're non technical: wordpress.com - choose site name, create account, make website. Then if you want to grow you can pay for a domain, custom plugins, themes, shop. If you really want to grow then you can bring your data out and setup your own (or pay someone to setup) a wordpress.org instance. Thousands of options for hosting, themes, whatever.
And: compared to the other builders like Wix, Squarespace etc, you're not locked in. If you make a thing on wordpress.com or wordpress.org and want to escape, you just export your stuff in a common XML format. You get none of that with the commercial options.
So, yeh, however much HN likes to hate on it, it's still the best platform of choice for non-technicals to get stuff on the web.
Then WordPress is just your private CMS/UI for making changes, and it generates static files that are uploaded to a webhost like CloudFlare Pages, GitHub Pages, etc.
I think a crawler that generates a static directory from your site probably the best approach since it generalizes over any site. Even better if you're able to declare all routes ahead of time.
I once worked for a US state government agency and my coworker was the main admin of our WordPress based portal and it was crazy how much work it was to keep working.
There's ways that prevent it -
- Freeze all code after an update through permissions
- Don't make most directories writeable
- Don't allow file uploads, or limit file uploads to media
There's a few plugins that do this, but vanilla WP is dangerous.
I never hosted WP, but as soon as you have a HTTP server expose to the internet you will get request to /wp-login and such. It as become a good way to find bots also. If I see an IP requesting anything from a popular CMS, hop it goes in the iptables holes
I deployed this, instead of my usual honeypot script.
It's not working very well.
In the web server log, I can see that the bots are not downloading the whole ten megabyte poison pill.
They are cutting off at various lengths. I haven't seen anything fetch more than around 1.5 Mb of it so far.
Or is it working? Are they decoding it on the fly as a stream, and then crashing? E.g. if something is recorded as having read 1.5 Mb, could it have decoded it to 1.5 Gb in RAM, on the fly, and crashed?
Try content labyrinth. I.e. infinitely generated content with a bunch of references to other generated pages. It may help against simple wget and till bots adapt.
That will be your contribution. If others join scrapping will become very pricey. Till bots become smarter. But then they will not download much of generated crap. Which makes it cheaper for you.
Anyway, from bots perspective labyrinths aren't the main problem. Internet is being flooded with quality LLM-generated content.
The labyrinth doesn't have to be fast, and things like iocaine (https://iocaine.madhouse-project.org/) don't use much CPU if you don't go and give them something like the Complete Works of Ahakespeare as input (Mine is using Moby Dick), and can easily be constrained with cgroups if you're concerned about resource usage.
I've noticed that LLM scrapers tend to be incredibly patient. They'll wait for minutes for even small amounts of text.
Kinda wonder if a "content labyrinth" could be used to influence the ideas / attitudes of bots -- fill it with content pro/anti Communism, or Capitalism, or whatever your thing is, hope it tips the resulting LLM towards your ideas.
I currently cannot tell without making a little configuration change, because as soon as an IP address is logged as having visited the trap URL (honeypot, or zipbomb or whatever), a log monitoring script bans that client.
Secondly, I know that most of these bots do not come back. The attacks do not reuse addresses against the same server in order to evade almost any conceivable filter rule that is predicated on a prior visit.
I believe Apache is logging complete requests. For instance, in the case of clients sent to a honeypot, I see a log entry appear when I pick a honeypot script from the process listing and kill it. That could be hours after the client connected.
The timestamps logged are connection time not completion time. E.g. here is a pair of consecutive logs:
Perhaps need to semi-randomize the file size?
I'm guessing some of the bots have a hard limit to the size of the resource they will download.
Many of these are annoying LLM training/scraping bots (in my case anyway).
So while it might not crash them if you spit out a 800KB zipbomb, at least it will waste computing resources on their end.
This topic comes up from time to time and I'm surprised no one yet mentioned the usual fearmongering rhetoric of zip bombs being potentially illegal.
I'm not a lawyer, but I'm yet to see a real life court case of a bot owner suing a company or an individual for responding to his malicious request with a zip bomb. The usual spiel goes like this: responding to his malicious request with a malicious response makes you a cybercriminal and allows him (the real cybercriminal) to sue you. Again, except of cheap talk I've never heard of a single court case like this. But I can easily imagine them trying to blackmail someone with such cheap threats.
I cannot imagine a big company like Microsoft or Apple using zip bombs, but I fail to see why zip bombs would be considered bad in any way. Anyone with an experience of dealing with malicious bots knows the frustration and the amount of time and money they steal from businesses or individuals.
>On my server, I've added a middleware that checks if the current request is malicious or not.
There's a lot of trust placed in:
>if (ipIsBlackListed() || isMalicious()) {
Can someone assigned a previously blacklisted IP or someone who uses a tool to archive the website that mimics a bot be served malware? Is the middleware good enough or "good enough so far"?
Close enough to 100% of my internet traffic flows through a VPN. I have been blacklisted by various services upon connecting to a VPN or switching servers on multiple occasions.
A user has to manually unpack a zip bomb, though. They have to open the file and see "uncompressed size: 999999999999999999999999999" and still try to uncompress it, at which point it's their fault when it fills up their drive and fails. So I don't think there's any ethical dilemma there.
For some reason I was under the impression that browsers had the ability to transparently decompress certain archive formats? I may be thinking of less and gzip though
Zip bombs are fun. I discovered a vulnerability in a security product once where it wouldn’t properly scan a file for malware if the file was or contained a zip archive greater than a certain size.
The practical effect of this was you could place a zip bomb in an office xml document and this product would pass the ooxml file through even if it contained easily identifiable malware.
Undoubtedly. If you go poking around most any security product (the product I was referring to was not in the EDR space,) you'll see these sorts of issues all over the place.
It does not have to be the way it is. Security vendors could do a much better job testing and red teaming their products to avoid bypasses, and have more sensible defaults.
> For the most part, when they do, I never hear from them again. Why? Well, that's because they crash right after ingesting the file.
I would have figured the process/server would restart, and restart with your specific URL since that was the last one not completed.
What makes the bots avoid this site in the future? Are they really smart enough to hard-code a rule to check for crashes and avoid those sites in the future?
Seems like an exponential backoff rule would do the job: I'm sure crashes happen for all sorts of reasons, some of which are bugs in the bot, even on non-adversarial input.
I do something similar using a script I've cobbled together over the years. Once a year I'll check the 404 logs and add the most popular paths trying to exploit something (ie ancient phpmyadmin vulns) to the shitlist. Requesting 3 of those URLs adds that host to a greylist that only accepts requests to a very limited set of legitimate paths.
Though, bots may not support modern compression standards. Then again, that may be a good way to block bots: every modern browser supports zstd, so just force that on non-whitelisted browser agents and you automatically confuse scrapers.
If you nest the gzip inside another gzip it gets even smaller since the blocks of compressed '0' data are themselves low entropy in the first generation gzip. Nested zst reduces the 10G file to 99 bytes.
Can you hand edit to create recursive file structures to make it infinite? I used to use debug in dos to make what appeared to be gigantic floppy discs by editing the fat
It would need a bot that is accessing files via hyperlink with an aim to decompress them and riffle through their contents. The compressed file can be delivered over a compressed response to achieve the two layers, cutting down significantly on the outbound traffic. passwd.zst, secrets.docx, etc. would look pretty juicy. Throw some bait in honeypot directories (exposed for file access) listed in robots.txt and see who takes it.
Last time I checked, the tab keeps loading, freezes, and the process that's assigned to rendering the tab gets killed when it eats too much RAM. Might cause a "this tab is slowing down your browser" popup or general browser slowness, but nothing too catastrophic.
How bad the tab process dying is, depends per browser. If your browser does site isolation well, it'll only crash that one website and you'll barely notice. If that process is shared between other tabs, you might lose state there. Chrome should be fine, Firefox might not be depending on your settings and how many tabs you have open, with Safari it kind of depends on how the tabs were opened and how the browser is configured. Safari doesn't support zstd though, so brotli bombs are the best you can do with that.
So I actually do this (use compression to filter out bots) for my one million checkboxes Datastar demo[1]. It relies heavily on streaming the whole user view on every interaction. With brotli over SSE you can easily hit 200:1 compression ratios[2]. The problem is a malicious actor could request the stream uncompressed. As brotli is supported by 98% of browsers I don't push data to clients that don't support brotli compression. I've also found a lot of scrapers and bots don't support it so it works quite well.
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[ 12.5 ms ] story [ 1113 ms ] threadAmazon's scraper doesn't back off. Meta, google, most of the others with identifiable user agents back off, Amazon doesn't.
tcpdrop shouldn't self DOS though, it's using less resources. Even if other end does a retry, it will do it after a timeout; in the meantime, the other end has a socket state and you don't, that's a win.
(I don't think your blog qualifies as shady … but you're not in my allowlist, either.)
So if I visit https://anubis.techaro.lol/ (from the "Anubis" link), I get an infinite anime cat girl refresh loop — which honestly isn't the worst thing ever?
But if I go to https://xeiaso.net/blog/2025/anubis/ and click "To test Anubis, click here." … that one loads just fine.
Neither xeserv.us nor techaro.lol are in my allowlist. Curious that one seems to pass. IDK.
The blog post does have that lovely graph … but I suspect I'll loop around the "no cookie" loop in it, so the infinite cat girls are somewhat expected.
I was working on an extension that would store cookies very ephemerally for the more malicious instances of this, but I think its design would work here too. (In-RAM cookie jar, burns them after, say, 30s. Persisted long enough to load the page.)
Is your browser passing a referrer?
I used cookie blockers for a long time, but always ended up having to whitelist some sites even though I didn't want their cookies because the site would misbehave without them. Now I just stopped worrying.
"Hurting people is wrong, so you should not defend yourself when attacked."
"Imprisoning people is wrong, so we should not imprison thieves."
Also the modern telling of Robin Hood seems to be pretty generally celebrated.
Two wrongs may not make a right, but often enough a smaller wrong is the best recourse we have to avert a greater wrong.
The spirit of the proverb is referring to wrongs which are unrelated to one another, especially when using one to excuse another.
The logic of terrorists and war criminals everywhere.
Do you really want to live in a society were all use of punishment to discourage bad behaviour in others? That is a game theoretical disaster...
Crime and Justice are not the same.
If you cannot figure that out, you ARE a major part of the problem.
Keep thinking until you figure it out for good.
This is exactly what Californian educators told kids who were being bullied in the 90's.
They made the request. Respond accordingly.
https://williamgibson.fandom.com/wiki/ICE
Bad bots don't even read robots.txt.
I had other ideas too, but I don't know how well some of them will work (they might depend on what bots they are).
An alternative might be to use Brotli which has a static dictionary. Maybe that can be used to achieve a high compression ratio.
For example, with gzip using default options:
Two bytes difference for a 1GiB sequence of “aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa…” (\141) compared to a sequence of \000.I'm sure though that if it was as simples as that we wouldn't even have a name for it.
It's just nobody usually implements a limit during decompression because people aren't usually giving you zip bombs. And sometimes you really do want to decompress ginormous files, so limits aren't built in by default.
Your given language might not make it easy to do, but you should pretty much always be able to hack something together using file streams. It's just an extra step is all.
It's intuitively extremely strange to me!
Even ignoring how zips work: Memory needs to be allocated in chunks. So before allocating a chunk, you can check if the new memory use will be over a threshold. CPU is used by the program instructions you control, so you can put checks at significant points in your program to see if it hit a threshold. Or you can have a thread you kill after a certain amount of time.
But the way zips do work makes it a lot simpler: Fundamentally it's "output X raw bytes, then repeat Y bytes from location Z" over and over. Abort if those numbers get too big.
cgroups with hard-limits will let the external tool's process crash without taking down the script or system along with it.
This is exactly the same idea as partitioning, though.
In a practical sense, how's that different from creating a N-byte partition and letting the OS return ENOSPC to you?
Also zip bombs are not comically large until you unzip them.
Also you can just unpack any sort of compressed file format without giving any thought to whether you are handling it safely.
Edit: And for folks who write their own web pages, you can always create zip bombs that are links on a web page that don't show up for humans (white text on white background with no highlight on hover/click anchors). Bots download those things to have a look (so do crawlers and AI scrapers)
It's also not a common metric you can filter on in open firewalls since you must lookup and maintain a cache of IP to ASN, which has to be evicted and updated as blocks still move around.
Automated banning is harder, you'd probably want a heuristic system and look up info on IPs.
IPv4 with NAT means you can "overban" too.
https://github.com/skeeto/endlessh
I did a version of this with my form for requesting an account on my fediverse server. The problem I was having is that there exist these very unsophisticated bots that crawl the web and submit their very unsophisticated spam into every form they see that looks like it might publish it somewhere.
First I added a simple captcha with distorted characters. This did stop many of the bots, but not all of them. Then, after reading the server log, I noticed that they only make three requests in a rapid succession: the page that contains the form, the captcha image, and then the POST request with the form data. They don't load neither the CSS nor the JS.
So I added several more fields to the form and hid them with CSS. Submitting anything in these fields will fail the request and ban your session. I also modified the captcha, I made the image itself a CSS background, and made the src point to a transparent image instead.
And just like that, spam has completely stopped, while real users noticed nothing.
RIP screen reader users?
This is the main reason I haven't installed zip bombs on my website already -- on the off chance I'd make someone angry and end up having to fend off a DDoS.
Currently I have some URL patterns to which I'll return 418 with no content, just to save network / processing time (since if a real user encounters a 404 legitimately, I want it to have a nice webpage for them to look at).
Should probably figure out how to wire that into fail2ban or something, but not a priority at the moment.
I don't think it's a terrible problem to solve these days, especially if you use one of the tarpitting implementations that use nftables/iptables/eBPF, but if you have one of those annoying Chinese bot farms with thousands of IP addresses hitting your server in turn (Huawei likes to do this), you may need to think twice before deploying this solution.
(Or rather, the tarpit should be programmed to do this, whether by having a maximum resource allocation or monitoring free system resources.)
The gzip bomb means you serve 10MB but they try to consume vast quantities of RAM on their end and likely crash. Much better ratio.
[0]: https://en.wikipedia.org/wiki/Chunked_transfer_encoding
See https://en.wikipedia.org/wiki/Slowloris_(cyber_attack)
Most of the bots I've come across are fairly dumb however, and those are pretty easy to detect & block. I usually use CrowdSec (https://www.crowdsec.net/), and with it you also get to ban the IPs that misbehave on all the other servers that use it before they come to yours. I've also tried turnstile for web pages (https://www.cloudflare.com/application-services/products/tur...) and it seems to work, though I imagine most such products would, as again most bots tend to be fairly dumb.
I'd personally hesitate to do something like serving a zip bomb since it would probably cost the bot farm(s) less than it would cost me, and just banning the IP I feel would serve me better than trying to play with it, especially if I know it's misbehaving.
Edit: Of course, the author could state that the satisfaction of seeing an IP 'go quiet' for a bit is priceless - no arguing against that
Later on, browsers started to check for actual content I think, and would abort such requests.
https://medium.com/@bishr_tabbaa/when-smart-ships-divide-by-...
"On 21 September 1997, the USS Yorktown halted for almost three hours during training maneuvers off the coast of Cape Charles, Virginia due to a divide-by-zero error in a database application that propagated throughout the ship’s control systems."
" technician tried to digitally calibrate and reset the fuel valve by entering a 0 value for one of the valve’s component properties into the SMCS Remote Database Manager (RDM)"
https://www.google.com/search?q=windows+nt+bug+affects+ship
I think this was it:
https://freedomhacker.net/annoying-favicon-crash-bug-firefox...
Years later I was finally able to open it.
Among things that didn't work were qutebrowser, icecat, nsxiv, feh, imv, mpv. I did worry at first the file was corrupt, I was redownloading it, comparing hashes with a friend, etc. Makes for an interesting benchmark, I guess.
For others curious, here's the file: https://0x0.st/82Ap.png
I'd say just curl/wget it, don't expect it to load in a browser.
Old school acdsee would have been fine too.
I think it's all the pixel processing on the modern image viewers (or they're just using system web views that isn't 100% just a straight render).
I suspect that the more native renderers are doing some extra magic here. Or just being significantly more OK with using up all your ram.
It also pans and zooms swiftly
Partially zoomed in was fine, but zooming to maximum fidelity resulted in the tab crashing (it was completely responsive until the crash). Looks like Safari does some pretty smart progressive rendering, but forcing it to render the image at full resolution (by zooming in) causes the render to get OOMed or similar.
Preview on a mac handles the file fine.
Pan&zoom works instantly with a blurry preview and then takes another 5-10s to render completely.
I suggested to try the HN beloved Sumatra PDF. Ugh, it couldn't cope with it normally. Chrome did it better coped better.
Takes a few seconds, but otherwise seems pretty ok in desktop Safari. Preview.app also handles it fine (albeit does allocate an extra ~1-2GB of RAM)
Surprisingly, Windows 95 didn't die trying to load it, but quite a lot of operations in the system took noticeably longer than they normally did.
Any ideeas?
there are other techniques. for example: hold a connection open and only push out a few bytes every few seconds - whether that's cheap for you or not depends on your servers concurrency model (if it's 1 OS thread per connection, then you'd DOS yourself with this - but with an evented model you should be good). if the bot analyzes images or pdfs you could try toxic files that exploit known weaknesses which lead to memory corruption to crash them; depends on the bots capabilities and used libraries of course.
yes "<div>"|dd bs=1M count=10240 iflag=fullblock|gzip | pv > zipdiv.gz
Resulting file is about 15 mib long and uncompresses into a 10 gib monstrosity containing 1789569706 unclosed nested divs
Also you can reverse many DoD vectors depending on how you are setup and costs. For example reverse Slowloris attack and use up their connections.
I am not sure how that could’ve worked. Unless the real /dev tree was exposed to your webserver’s chroot environment, this would’ve given nothing special except “file not found”.
The whole point of chroot for a webserver was to shield clients from accessing special files like that!
Even if you knew it was done with a symlink you don't know that - these days odds are it'd run in a container or vm, and so having access to /dev/zero means very little.
Write an ordinary static html page and fill a <p> with infinite random data using <!--#include file="/dev/random"-->.
or would that crash the server?
Ok, not a real zip bomb, for that we would need a kernel module.
Or a userland fusefs program, nice funky idea actually (with configurable dynamic filenames, e.g. `mnt/10GiB_zeropattern.zip`...
Like, a legitimate crawler suing you and alleging that you broke something of theirs?
I'll play the side of the defender and you can play the "bot"/bot deployer.
> it could serve the zip bomb to a legitimate bot.
Can you define the difference between a legitimate bot, and a non legitimate bot for me ?
The OP didn't mention it, but if we can assume they have SOME form of robots.txt (safe assumtion given their history), would those bots who ignored the robots be considered legitimate/non-legitimate ?
Almost final question, and I know we're not lawyers here, but is there any precedent in case law or anywhere, which defines a 'bad bot' in the eyes of the law ?
Final final question, as a bot, do you believe you have a right or a privilege to scrape a website ?
Well by default every bot is legitimate, an illegitimate bot might be one that’s probing for security vulnerabilities (but I’m not even sure if that’s illegal if you don’t damage the server as a side effect, ie if you only try to determine the Wordpress or SSHD version running on the server for example).
> The OP didn't mention it, but if we can assume they have SOME form of robots.txt (safe assumtion given their history), would those bots who ignored the robots be considered legitimate/non-legitimate ?
robots.txt isn’t legally binding so I don’t think ignoring it makes a bot illegitimate.
> Almost final question, and I know we're not lawyers here, but is there any precedent in case law or anywhere, which defines a 'bad bot' in the eyes of the law ?
There might be but I don’t know any.
> Final final question, as a bot, do you believe you have a right or a privilege to scrape a website ?
Well I’m not a bot but I think I have the right to build bots to scrape websites (and not get served malicious content designed to sabotage my computer). You can decline service and just serve error pages of course if you don’t like my bot.
https://en.wikipedia.org/wiki/Mantrap_(snare)
Of course their computers will live, but if you accidentally take down your own ISP or maybe some third-party service that you use for something, I'd think they would sue you.
>Disallow: /zipbomb.html
Legitimate crawlers would skip it this way only scum ignores robots.txt
The server owner can make an easy case to the jury that it is a booby trap to defend against trespassers.
I don't know of any online cases, but the law in many (most?) places certainly tends to look unfavourably on physical booby-traps. Even in the US states with full-on “stand your ground” legislation and the UK where common law allows for all “reasonable force” in self-defence, booby-traps are usually not considered self-defence or standing ground. Essentially if it can go off automatically rather than being actioned by a person in a defensive action, it isn't self-defence.
> Who […] is going to prosecute/sue the server owner?
Likely none of them. They might though take tit-for-tat action and pull that zipbomb repeatedly to eat your bandwidth, and they likely have more and much cheaper bandwidth than your little site. Best have some technical defences ready for that, as you aren't going to sue them either: they are probably running from a completely different legal jurisdiction and/or the attack will come from a botnet with little or no evidence trail wrt who kicked it off.
> pull that zipbomb repeatedly to eat your bandwidth, and they likely have more and much cheaper bandwidth than your little site.
Go read what a zip bomb is. There is one that is only a few KB, which is comparable in server load + bandwidth to a robots.txt.
No need to be a dick. Especially when you yourself are in the process of not understanding what others are saying.
I know full well what a zipbomb is. A large compressed file still has some size even in compressed form (without nesting, 1G of minimal entropy data is ~1M gzipped). If someone has noticed your bomb and worked around it by implementing relevant checks (or isn't really affected by it because of already having had those checks in place), they can get a little revenge by soaking up your bandwidth downloading it many times. OK, so nested that comes down to a few Kb, they can still throw a botnet at that, or some other content on your site, and cause you some faf, if they wish to engage in tit-for-tat action. Also: nesting doesn't work when you are using HTTP transport compression as your delivery mechanism, which is what is being discussed here: “standard” libraries supporting compressed HTTP encodings don't generally unpack nested content. There is no “Accept-Encoding: gzip+gzip” or similar.
Most, perhaps the vast majority, won't care to make the effort, so this could be considered a hypothetical, but some might. There were certainly cases, way back in my earlier days online, of junk mailers and address scrapers deliberately wasting bandwidth of sites that encouraged the use of tools like FormFucker or implemented scraper sinkholes.
Neither is the HTTP specification. Nothing is stopping you from running a Gopher server on TCP port 80, should you get into trouble if it happens to crash a particular crawler?
Making a HTTP request on a random server is like uttering a sentence to a random person in a city: some can be helpful, some may tell you to piss off and some might shank you. If you don't like the latter, then maybe don't go around screaming nonsense loudly to strangers in an unmarked area.
I just assumed court might say there is a difference between you requesting all guess-able endpoints and find 1 endpoint which will harm your computer (while there was _zero_ reason for you to access that page) and someone putting zipbomb into index.html to intentionally harm everyone.
That is not the case in this context. robots.txt is the only thing that specifies the document URL, which it does so in a "disallow" rule. The argument that they did not know the request would be responded to with hostility could be moot in that context (possibly because a "reasonable person" would have chosen not to request the disallowed document but I'm not really familiar with when that language applies).
> by deleting local files for example
This is a qualitatively different example than a zip bomb, as it is clearly destructive in a way that a zip bomb is not. True that a zip bomb could cause damage to a system but it's not a guarantee, while deleting files is necessarily damaging. Worse outcomes from a zip bomb might result in damages worthy of a lawsuit but the presumed intent (and ostensible result) of a zip bomb is to effectively cause the recipient machine to involuntarily shut down, which a court may or may not see as legitimate given the surrounding context.
The CFAA[1] prohibits:
> knowingly causes the transmission of a program, information, code, or command, and as a result of such conduct, intentionally causes damage without authorization, to a protected computer;
As far as I can tell (again, IANAL) there isn't an exception if you believe said computer is actively attempting to abuse your system[2]. I'm not sure if a zip bomb would constitute intentional damage, but it is at least close enough to the line that I wouldn't feel comfortable risking it.
[1]: https://www.law.cornell.edu/uscode/text/18/1030
[2]: And of course, you might make a mistake and incorrectly serve this to legitimate traffic.
> which is used in or affecting interstate or foreign commerce or communication, including a computer located outside the United States that is used in a manner that affects interstate or foreign commerce or communication of the United States
Assuming the server is running in the states, I think that would apply unless the client is in the same state as the server, in which case there is probably similar state law that comes into affect. I don't see anything there that excludes a client, and that makes sense, because otherwise it wouldn't prohibit having a site that tricks people into downloading malware.
Also, the protected computer has to be involved in commerce. Unless they are accessing the website with the zip bomb using a computer that also is uses for interstate or foreign commerce, it won't qualify.
So what? It isn't in the section I quoted above. I could be wrong, but my reading is that transmitting information that can cause damage with the intent of causing damage is a violation, regardless of if you "access" another system.
> Also, the protected computer has to be involved in commerce
Or communication.
Now, from an ethics standpoint, I don't think there is anything wrong with returning a zipbomb to malicious bots. But I'm not confident enough that doing so is legal that I would risk doing so.
You can't read laws in sections like that. They sections go together. The entire law is about causing damage through malicious access. But servers don't access clients.
The section you quoted isn't relevant because the entire law is about clients accessing servers, not servers responding to clients.
In the US, virtually everything is involved in 'interstate commerce'. See https://en.wikipedia.org/wiki/Commerce_Clause
> The Commerce Clause is the source of federal drug prohibition laws under the Controlled Substances Act. In a 2005 medical marijuana case, Gonzales v. Raich, the U.S. Supreme Court rejected the argument that the ban on growing medical marijuana for personal use exceeded the powers of Congress under the Commerce Clause. Even if no goods were sold or transported across state lines, the Court found that there could be an indirect effect on interstate commerce and relied heavily on a New Deal case, Wickard v. Filburn, which held that the government may regulate personal cultivation and consumption of crops because the aggregate effect of individual consumption could have an indirect effect on interstate commerce.
In particular, the interstate commerce clause is very over-reaching. It's been ruled that someone who grew their own crops to feed to their own farm animals sold locally was conducting interstate commerce because they didn't have to buy them from another state.
IANAL
(I'm half-joking, half-crying. It's how everything else works, basically. Why would it not work here? You could even go as far as explicitly calling it a "zipbomb test delivery service". It's not your fault those bots have no understanding what they're connecting to…)
But if it matters pay your lawyer and if it doesn’t matter, it doesn’t matter.
I know it's slightly off topic, but it's just so amusing (edit: reassuring) to know I'm not the only one who, after 1 hour of setting up Wordpress there's a PHP shell magically deployed on my server.
But it's such a bad platform that there really isn't any reason for anybody to use WordPress for anything. No matter your use case, there will be a better alternative to WordPress.
I've tried Drupal in the past for such situations, but it was too complicated for them. That was years ago, so maybe it's better now.
[0] https://decapcms.org/
25 years ago we used Microsoft Frontpage for that, with the web root mapped to a file share that the non-technical secretary could write to and edit it as if it were a word processor.
Somehow I feel we have regressed from that simplicity, with nothing but hand waving to make up for it. This method was declared "obsolete" and ... Wordpress kludges took its place as somehow "better". Someone prove me wrong.
The other part is clients freaking out after Frontpage had a series of dangerous CVEs all in a row.
And then finally every time a part of Frontpage got popular, MS would deprecate the API and replace it with a new one.
Wordpress was in the right place at the right time.
In one, multiple users can login, edit WYSIWYG, preview, add images, etc, all from one UI. You can access it from any browser including smart phones and tablets.
In the other, you get to instruct users on git, how to deal with merge conflicts, code review (two people can't easily work on a post like they can in wordpress), previews require a manual build, you need a local checkout and local build installation to do the build. There no WYSIWYG, adding images is a manual process of copying a file, figuring out the URL, etc... No smartphone/tablet support. etc....
I switched by blog from wordpress install to a static site geneator because I got tired of having to keep it up to date but my posting dropped because of friction of posting went way up. I could no longer post from a phone. I couldn't easily add images. I had to build to preview. And had to submit via git commits and pushes. All of that meant what was easy became tedious.
I build mine with GitHub Actions and host it free on Pages.
IIRC, Eleventy printed lots of out-of-date warnings when I installed it and/or the default style was broken in various ways which didn't give me much confidence.
My younger sister asked me to help her start a blog. I just pointed her to substack. Zero effort, easy for her.
For example (not affiliated with them) https://www.siteleaf.com/
Edit: I actually feel a bit sorry for the SurrealCMS developer. He has a fantastic product that should be an industry standard, but it's fairly unknown.
> new
Pretty sure Drupal has been around for like, 20 years or so. Or is this a different Drupal?
It appears Drupal CMS is a customized version of Drupal that is easier for less tech-savvy folks to get up and running. At least, that's the impression I got reading through the marketing hype that "explains" it with nothing but buzzwords.
And only hosted option for the copyrighted code starts at 300/y
these don't cover any use case people use WordPress for.
- very hard to hack because we pre render all assets to a Cloudflare kv store
- public website and CMS editor are on different domains
Basically very hard to hack. Also as a bonus is much more reliable as it will only go down when Cloudflare does.
Could be automated better (drop ZIP to a share somewhere where it gets processed and deployed) but best of both worlds.
If they are selling anything on their website, it's probably going to be through a cloud hosted third party service and then it's just an embedded iframe on their website.
If you're making an entire web shop for a very large enterprise or something of similar magnitude, then you have to ask somebody else than me.
Everything I've built in the past like 5 years has been almost entirely pure ES6 with some helpers like jsviews.
https://survey.stackoverflow.co/2024/technology#1-web-framew...
https://youmightnotneedjquery.com/
And: compared to the other builders like Wix, Squarespace etc, you're not locked in. If you make a thing on wordpress.com or wordpress.org and want to escape, you just export your stuff in a common XML format. You get none of that with the commercial options.
So, yeh, however much HN likes to hate on it, it's still the best platform of choice for non-technicals to get stuff on the web.
Then WordPress is just your private CMS/UI for making changes, and it generates static files that are uploaded to a webhost like CloudFlare Pages, GitHub Pages, etc.
Now that plugin became a service, at which point you might just use a WP host and let them do their thing.
I think a crawler that generates a static directory from your site probably the best approach since it generalizes over any site. Even better if you're able to declare all routes ahead of time.
>Oh look 3 separate php shells with random strings as a name
Never less than 3, but always guaranteed.
I've used this teaching folks devops, here deploy your first hello world nginx server... huh what are those strange requests in the log?
There's a few plugins that do this, but vanilla WP is dangerous.
https://www.hackerfactor.com/blog/index.php?/archives/762-At...
It's not working very well.
In the web server log, I can see that the bots are not downloading the whole ten megabyte poison pill.
They are cutting off at various lengths. I haven't seen anything fetch more than around 1.5 Mb of it so far.
Or is it working? Are they decoding it on the fly as a stream, and then crashing? E.g. if something is recorded as having read 1.5 Mb, could it have decoded it to 1.5 Gb in RAM, on the fly, and crashed?
There is no way to tell.
PS: I'm on the bots side, but don't mind helping.
Anyway, from bots perspective labyrinths aren't the main problem. Internet is being flooded with quality LLM-generated content.
I've noticed that LLM scrapers tend to be incredibly patient. They'll wait for minutes for even small amounts of text.
Secondly, I know that most of these bots do not come back. The attacks do not reuse addresses against the same server in order to evade almost any conceivable filter rule that is predicated on a prior visit.
> as soon as an IP address is logged as having visited the trap URL (honeypot, or zipbomb or whatever), a log monitoring script bans that client.
Is this not why they aren’t getting the full file?
Many of these are annoying LLM training/scraping bots (in my case anyway). So while it might not crash them if you spit out a 800KB zipbomb, at least it will waste computing resources on their end.
I'm not a lawyer, but I'm yet to see a real life court case of a bot owner suing a company or an individual for responding to his malicious request with a zip bomb. The usual spiel goes like this: responding to his malicious request with a malicious response makes you a cybercriminal and allows him (the real cybercriminal) to sue you. Again, except of cheap talk I've never heard of a single court case like this. But I can easily imagine them trying to blackmail someone with such cheap threats.
I cannot imagine a big company like Microsoft or Apple using zip bombs, but I fail to see why zip bombs would be considered bad in any way. Anyone with an experience of dealing with malicious bots knows the frustration and the amount of time and money they steal from businesses or individuals.
This is what trips me up:
>On my server, I've added a middleware that checks if the current request is malicious or not.
There's a lot of trust placed in:
>if (ipIsBlackListed() || isMalicious()) {
Can someone assigned a previously blacklisted IP or someone who uses a tool to archive the website that mimics a bot be served malware? Is the middleware good enough or "good enough so far"?
Close enough to 100% of my internet traffic flows through a VPN. I have been blacklisted by various services upon connecting to a VPN or switching servers on multiple occasions.
A user has to manually unpack a zip bomb, though. They have to open the file and see "uncompressed size: 999999999999999999999999999" and still try to uncompress it, at which point it's their fault when it fills up their drive and fails. So I don't think there's any ethical dilemma there.
The practical effect of this was you could place a zip bomb in an office xml document and this product would pass the ooxml file through even if it contained easily identifiable malware.
The file size problem is still an issue for many big name EDRs.
Scanning them are resources intensive. The choice are (1) skip scanning them; (2) treat them as malware; (3) scan them and be DoS'ed.
(deferring the decision to human iss effectively DoS'ing your IT support team)
I would have figured the process/server would restart, and restart with your specific URL since that was the last one not completed.
What makes the bots avoid this site in the future? Are they really smart enough to hard-code a rule to check for crashes and avoid those sites in the future?
Though, bots may not support modern compression standards. Then again, that may be a good way to block bots: every modern browser supports zstd, so just force that on non-whitelisted browser agents and you automatically confuse scrapers.
it is basically a quine.
How bad the tab process dying is, depends per browser. If your browser does site isolation well, it'll only crash that one website and you'll barely notice. If that process is shared between other tabs, you might lose state there. Chrome should be fine, Firefox might not be depending on your settings and how many tabs you have open, with Safari it kind of depends on how the tabs were opened and how the browser is configured. Safari doesn't support zstd though, so brotli bombs are the best you can do with that.
[1] checkboxes demo https://checkboxes.andersmurphy.com
[2] article on brotli SSE https://andersmurphy.com/2025/04/15/why-you-should-use-brotl...