ZH2003-3SP (security patch): multiple vulnerabilities in mod_gzip 1.3.x debug
mode

Released: 7 October 2003
Name: mod_gzip
Affected versions: all versions (debug mode)
Issue: stack overflow, format string and insecure file creation
Author: Astharot (at Zone-H.org)
Vendor: http://sourceforge.net/projects/mod-gzip/

Description
**********
Zone-H Security Team wrote a patch for the unresolved vulnerabilities found in
the debug mode of mod_gzip. According to the informations found on mod_gzip
website, mod_gzip "is an Internet Content Acceleration module for the popular
Apache Web Server. It compresses the contents delivered to the client."

Details
**********
Matthew Murphy (mattmurphy[at]kc.rr.com) discovered multiple vulnerabilities in
the debug mode of mod_gzip. The first vulnerability is a stack overflow. It has
been reported that by requesting a long filename, a buffer overflow occours in
the logging mechanism. If it's possible overwrite the return address, it's
possible to execute arbitrary code with the privilege of the webserver. The
second vulnerability is a format string. A remote user can submit a specially
crafted HTTP GET request to trigger a format string flaw in the use of the
Apache logging mechanism. An attacker may be able to execute arbitrary code. The
third and last vuolnerability is an insecure file creation. A local user can
create a symbolic link from the temporary file name to a critical file. When
mod_gzip is executed, the linked file will be overwritten. mod_gzip logs some
debug events with root privileges, so a local user can potentially exploit this
to gain root privileges on the system.

Solution
**********
It's possible to download the patch here:
http://www.zone-h.org/download/file=4954/.

Download the patch, then in the source directory type:

patch < mod_gzip.diff

then recompile mod_gzip.


Link to this advisory:
http://www.zone-h.org/en/advisories/read/id=3225/ 

Astharot
-- 
http://www.zone-h.org - astharot@zone-h.org
PGP Key: http://www.gife.org/astharot.asc

Linux User #292132