[ltt-dev] [geissert at debian.org: Bug#598309: ust-bin: CVE-2010-3386: insecure library loading]

[Mathieu Desnoyers]

* Jon Bernard (jbernard at debian.org) wrote:
> I just received this bug report and wanted to forward it here to get any
> thoughts and/or opinions.
> 
> -- 
> Jon
> 
> ----- Forwarded message from Raphael Geissert <geissert at debian.org> -----
> 
> Date: Tue, 28 Sep 2010 04:23:22 +0000
> From: Raphael Geissert <geissert at debian.org>
> To: submit at bugs.debian.org
> Subject: Bug#598309: ust-bin: CVE-2010-3386: insecure library loading
> Reply-To: Raphael Geissert <geissert at debian.org>, 598309 at bugs.debian.org
> 
> Package: ust-bin
> Version: 0.7-1
> Severity: grave
> Tags: security
> User: team at security.debian.org
> Usertags: ldpath
> 
> Hello,
> 
> During a review of the Debian archive, I've found your package to
> contain a script that can be abused by an attacker to execute arbitrary
> code.
> 
> The vulnerability is introduced by an insecure change to
> LD_LIBRARY_PATH, and environment variable used by ld.so(8) to look for
> libraries on a directory other than the standard paths.
> 
> Vulnerable code follows:
> 
> /usr/bin/usttrace line 136:
> 	    export LD_LIBRARY_PATH="$LD_LIBRARY_PATH:${LIBUST_PATH%libust.so}"
> /usr/bin/usttrace line 144:
> 	    export LD_LIBRARY_PATH="$LD_LIBRARY_PATH:${LIBUST_PATH%libust.so}"

Changing this for something like the following should do the trick:

if [ "x${LD_LIBRARY_PATH}" != "x" ]; then
	export LD_LIBRARY_PATH="${LD_LIBRARY_PATH}:${LIBUST_PATH%libust.so}"
else
	export LD_LIBRARY_PATH="${LIBUST_PATH%libust.so}"
fi

(untested, but should do the trick)

Note that I added extra braces ( ${} ) to delimit the variable more
clearly.

Thanks,

Mathieu


> 
> When there's an empty item on the colon-separated list of
> LD_LIBRARY_PATH, ld.so treats it as '.' (i.e. CWD/$PWD.)
> If the given script is executed from a directory where a potential,
> local, attacker can write files to, there's a chance to exploit this
> bug.
> 
> This vulnerability has been assigned the CVE id CVE-2010-3386. Please make sure
> you mention it when forwarding this report to upstream and when fixing
> this bug (everywhere: upstream and here at Debian.)
> 
> [0] http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2010-3386
> [1] http://security-tracker.debian.org/tracker/CVE-2010-3386
> 
> Sincerely,
> Raphael Geissert
> 
> 
> 
> ----- End forwarded message -----
> 
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-- 
Mathieu Desnoyers
Operating System Efficiency R&D Consultant
EfficiOS Inc.
http://www.efficios.com