Apache 1.3.29/2.X mod_rewrite Buffer Overflow Vulnerability CVE-2006-3747

[<David_Marcus () McAfee com>]

McAfee, Inc.
McAfee Avert(tm) Labs Security Advisory
Public Release Date: 2006-07-09

Apache 1.3.29/2.X mod_rewrite Buffer Overflow Vulnerability

CVE-2006-3747
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* Synopsis

Mod_rewrite is an Apache module that can be used to remap requests 
based on regular expression matches of the requested URI. A buffer 
overflow vulnerability exists when dealing with rewritten URI's that 
are prefixed with the LDAP protocol scheme.  

Exploitation leads to remote access to the vulnerable machine and 
therefore the risk factor is critical.

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* Vulnerable Systems

Apache 1.3.29/mod_rewrite
Apache 2.0.x/mod_rewrite - only 2.0.46 and higher are vulnerable
Apache 2.2.x/mod_rewrite

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* Vulnerability Information

The mod_rewrite module contains an off-by-one buffer overflow 
vulnerability when escaping an absolute URI scheme. The vulnerability 
occurs within escape_absolute_uri( ) when separating out tokens 
within an LDAP URL. Triggering the vulnerability results in a pointer 
to user-controlled data to be written outside of the bounds of a 
character pointer array, which in many cases can be used to gain 
complete control of the affected host.

Note that an LDAP-specific rule does not need to be exist to exploit 
the vulnerability. However, a rule must exist with the following 
properties:

- A rule must exist where the user can control the initial part of the
rewritten URL
- The rule must not contain a forbidden or gone flag [F or G]
- Rules with "noescape" [NE] flag settings are not affected.


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* Resolution

http://www.apache.org/dist/httpd/Announcement2.2.html

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* Credits

This vulnerability was discovered by Mark Dowd of McAfee Avert Labs.

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* Legal Notice

Copyright (C) 2006 McAfee, Inc.
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Best regards,

Dave Marcus, B.A., CCNA, MCSE
Security Research and Communications Manager
McAfee(r) Avert(r) Labs
(443) 321-3771 Office
(443) 668-0048 Mobile
McAfee Threat Center
<http://www.mcafee.com/us/threat_center/default.asp> 
McAfee Avert Labs Research Blog <http://www.avertlabs.com/research/blog>



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