Bug 638387 (CVE-2010-3369)

Summary: CVE-2010-3369 mono-debugger: insecure library loading vulnerability
Product: [Other] Security Response Reporter: Vincent Danen <vdanen>
Component: vulnerabilityAssignee: Red Hat Product Security <security-response-team>
Status: CLOSED UPSTREAM QA Contact:
Severity: low Docs Contact:
Priority: low    
Version: unspecifiedCC: paul
Target Milestone: ---Keywords: Security
Target Release: ---   
Hardware: All   
OS: Linux   
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Fixed In Version: Doc Type: Bug Fix
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Last Closed: 2012-08-16 17:52:14 UTC Type: ---
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oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
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Bug Depends On: 638388    
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Description Vincent Danen 2010-09-28 22:11:59 UTC 
Raphael Geissert conducted a review of various packages in Debian and found that mono-debugger 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/mdb and /usr/bin/mdb-symbolreader both re-set LD_LIBRARY_PATH insecurely:

export LD_LIBRARY_PATH="/usr/lib:${LD_LIBRARY_PATH}"

A solution is to patch the scripts 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-2010-3369.

[1] http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=598299
Comment 1 Vincent Danen 2010-09-28 22:13:09 UTC 
Created mono-debugger tracking bugs for this issue

Affects: fedora-all [bug 638388]
Comment 2 Tomas Hoger 2010-09-29 07:44:24 UTC 
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}
Comment 3 Vincent Danen 2012-08-16 17:52:14 UTC 
This looks to be corrected in 2.10 with this Pathclean() function:

 3 Pathclean ()
 4 {
 5  # Vulnerability fix for insecure path content
 6  # Make sure "::", "^:" or ":$" is not left in path arg $1
 7
 8  local tmp
 9  tmp=$(echo "$1" | sed -e 's/::\+// ; s/^:// ; s/:$//' )
10
11  [ "$tmp" ] && echo "$tmp"
12 }
13
14 LD_LIBRARY_PATH="@libdir@${LD_LIBRARY_PATH:+:$LD_LIBRARY_PATH}"
15 LD_LIBRARY_PATH=$(Pathclean "$LD_LIBRARY_PATH")
16 export LD_LIBRARY_PATH

which is the current version we provide:

Fedora-16: http://koji.fedoraproject.org/packages/mono-debugger/2.10/1.fc16
Fedora-17: http://koji.fedoraproject.org/packages/mono-debugger/2.10/3.fc17
Fedora-Rawhide: http://koji.fedoraproject.org/packages/mono-debugger/2.10/4.fc18