Comment by SonOfLilit
1 day ago
After having been bitten once (was teaching a competitive programming team, half the class got a blank page when submitting solutions, after an hour of debugging I narrowed it down to a few C++ types and keywords that cause 403 if they appear in the code, all of which happen to have meaning in Javascript), and again (working for a bank, we had an API that you're supposed to submit a python file to, and most python files would result in 403 but short ones wouldn't... a few hours of debugging and I narrowed it down to a keyword that sometimes appears in the code) and then again a few months later (same thing, new cloud environment, few hours burned on debugging[1]), I had the solution to his problem in mind _immediately_ when I saw the words "network error".
[1] the second time it happened, a colleague added "if we got 403, print "HAHAHA YOU'VE BEEN WAFFED" to our deployment script, and for that I am forever thankful because I saw that error more times than I expected
Do you remember if that was Cloudflare or some other likely WAF?
First time something on-prem, maybe F5. Second time AWS.
Oh, I just remembered I had another encounter with the AWS WAF.
I had a Jenkins instance in our cloud account that I was trying to integrate with VSTS (imagine github except developed by Microsoft, and still maintained, nevermind that they own github and it's undoubtedly a better product). Whenever I tried to trigger a build, it worked, but when VSTS did, it failed. Using a REST monitor service I was able to record the exact requests VSTS was making and prove that they work with curl from my machine... after a few nights of experimenting and diffing I noticed a difference between the request VSTS made to the REST monitor and my reproduction with curl: VSTS didn't send a "User-Agent" header, so curl supplied one by default unless I added I think -H "User-Agent:", and therefore did not trigger the first default rule in the AWS WAF, "if your request doesn't list a user agent you're a hacker".
HAHAHA I'VE BEEN WAFFED AGAIN.
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