owasp-modsecurity / owasp-modsecurity/ModSecurity

request on iis with more than 999 characters single value in cookie are getting blocked and no specific rule to fix

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2.x
Dominant language
C++
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Description

using owasp mod security on iis version 2.9.7, after june update the following bug started to happen

requests with a single cookie variable value of longer than 999 characters are being blocked with err connection reset or http protocol 2 error, no specific reason for the error is being logged.

note that its per variable length not on the total length of the cookie, so requests with two cookie variables each for example is 800 characters will pass.

no logs in the event viewer, and no clear rule id to find out what is happening.

disabling modsecurity the requests passes without a problem.

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Research direction

Reproduce the issue with ModSecurity 2.9.7 on IIS using a single cookie value longer than 999 characters, then compare the request behavior with ModSecurity disabled. Done means the request behavior and applicable rule or logged cause are identified, with a focused regression test or documented reproduction.

Written by the indexing model from the issue text.

Assessment

Tech stack
cpp
Domain
security
Issue type
Bug
Difficulty
4/5
Estimated time
3-5 days
Activity status
Stale
Clarity
Needs clarification
Newbie friendliness
35/100

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