owasp-modsecurity / owasp-modsecurity/ModSecurity

AuditLogs are logging binary data and getting huge

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#2,289 8 comments 0 reactions 1 assignee View on GitHub

@zimmerle is already working on this.

Since Apr 3, 2020.

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Description

Describe the bug
My audit logs have begun logging binary data under the C section for request body.
This is causing my log files to grow upwards of 5GB each even though they rotate once daily.

I am running the following system:

ModSecurity for Apache/2.9.2 (http://www.modsecurity.org/) configured. [-]
ModSecurity: APR compiled version="1.6.2"; loaded version="1.6.3"
ModSecurity: Loaded APR do not match with compiled!
ModSecurity: PCRE compiled version="8.39 "; loaded version="8.39 2016-06-14"
ModSecurity: LUA compiled version="Lua 5.1"
ModSecurity: YAJL compiled version="2.1.0"
ModSecurity: LIBXML compiled version="2.9.4"

I have numerous websites that are using ModSecurity through Apache but this only occurs with my installation of Nextcloud and only when very large video files (500MB and up) are uploaded from the Nextcloud app interface on my phone.
In my modsecurity.conf file I have the following set:
SecAuditLogParts ABDEFHIJZ
Removing the I fixes the issue for me so I am guessing that somehow modsecurity isn't recognizing that these particular body requests are a file upload of binary data. Maybe because the data is sent in chunks. I don't know.

Logs and dumps

Output of:

  1. DebugLogs (level 9)
  2. AuditLogs
  3. Error logs
  4. If there is a crash, the core dump file.

Notice: Be carefully to not leak any confidential information.

To Reproduce

Steps to reproduce the behavior:

A curl command line that mimics the original request and reproduces the problem. Or a ModSecurity v3 test case.

[e.g: curl "modsec-full/ca/..\..\..\..\..\..\/\etc/\passwd" or issue-394.json]

Expected behavior

A clear and concise description of what you expected to happen.

Server (please complete the following information):

  • ModSecurity version (and connector): libapache2-mod-security2 2.9.2-1
  • WebServer: Apache 2.4.29
  • OS (and distro): Ubuntu 18.04.4

Rule Set (please complete the following information):
OWASP ModSecurity Core Rule Set ver.3.2.0

Additional context

Add any other context about the problem here.

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