Bug 638396 (CVE-2010-3385)

Summary: CVE-2010-3385 tuxguitar: insecure library loading vulnerability
Product: [Other] Security Response Reporter: Vincent Danen <vdanen>
Component: vulnerabilityAssignee: Red Hat Product Security <security-response-team>
Status: NEW --- QA Contact:
Severity: low Docs Contact:
Priority: low    
Version: unspecifiedCC: mtasaka, oget.fedora
Target Milestone: ---Keywords: Security
Target Release: ---   
Hardware: All   
OS: Linux   
Whiteboard: public=20100928,reported=20100914,source=vendor-sec,impact=low,cvss2=3.7/AV:L/AC:H/Au:N/C:P/I:P/A:P,fedora-all/tuxguitar=affected
Fixed In Version: Doc Type: Bug Fix
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Bug Depends On: 638398    
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Description Vincent Danen 2010-09-28 18:28:04 EDT
Raphael Geissert conducted a review of various packages in Debian and found that tuxguitar contained a script that could be abused by an attacker to execute arbitrary code [1].

The vulnerability is due to an insecure change to LD_LIBRARY_PATH, and environment variable used by ld.so(8) to look for libraries in directories other than the standard paths.  When there is an empty item in the colon-separated list of directories in LD_LIBRARY_PATH, ld.so(8) treats it as a '.' (current working directory).  If the given script is executed from a directory where a local attacker could write files, there is a chance for exploitation.

In Fedora, /usr/bin/tuxguitar re-sets LD_LIBRARY_PATH insecurely:

##LIBRARY_PATH
LD_LIBRARY_PATH=${LD_LIBRARY_PATH}:/usr/lib/tuxguitar/
LD_LIBRARY_PATH=${LD_LIBRARY_PATH}:/lib
LD_LIBRARY_PATH=${LD_LIBRARY_PATH}:/usr/lib
LD_LIBRARY_PATH=${LD_LIBRARY_PATH}:/usr/lib/jni
LD_LIBRARY_PATH=${LD_LIBRARY_PATH}:/usr/local/lib
LD_LIBRARY_PATH=${LD_LIBRARY_PATH}:${MOZILLA_FIVE_HOME}
...
export LD_LIBRARY_PATH

A solution is to patch the script to test if $LD_LIBRARY_PATH is set first before attempting to modify it:

if [ -z ${LD_LIBRARY_PATH} ]; then
    export LD_LIBRARY_PATH=/usr/lib/foo
else
    export LD_LIBRARY_PATH=/usr/lib/foo:${LD_LIBRARY_PATH}
fi

This issue has been assigned the name CVE-2010-3385.

[1] http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=598307
Comment 1 Vincent Danen 2010-09-28 18:30:34 EDT
Created tuxguitar tracking bugs for this issue

Affects: fedora-all [bug 638398]
Comment 2 Tomas Hoger 2010-09-29 03:44:30 EDT
This one-liner should work as an alternative to if-else-fi fix:
export LD_LIBRARY_PATH=/usr/lib/foo${LD_LIBRARY_PATH:+:$LD_LIBRARY_PATH}