Most Microsoft DLL Hijacking Vulnerabilities Remain Unpatched

Strategic Security Survey: Global Threat, Local Pain

Only 15% of publicly known DLL hijacking vulnerabilities have been fixed, according to Slovenian security firm ACROS Security.

Nearly 100 days ago, the vulnerabilities -- also known as binary planting, DLL preloading, and insecure library loading -- as well as related EXE loading bugs were first disclosed. Attackers can exploit the vulnerabilities, which stem from the insecure manner in which Microsoft Windows performs file location searches, to run arbitrary code.

But to date, according to vulnerability information service Secunia, only 23 out of 151 DLL planting bugs have been fixed. On the upside, however, seven of the eight known EXE loading vulnerabilities have been patched.

"Interestingly, after some web browser vendors' initial quick response (Firefox, Opera, Safari), most of the fixes were done by smaller vendors, perhaps predominantly in open source software," said Mitja Kolsek, the CEO and CTO of ACROS, in a blog post.

But what accounts for the slow patching response by larger vendors to known vulnerabilities, given that they've had more than three months to fix the relevant flaws in their software? "In general, large vendors seem to be very slow in patching -- which is often rationalized by extensive testing they need to perform, but may also be due to their business models not providing sufficient rewards for security fixing," said Kolsek.

Unfortunately, beyond Secunia's list of vulnerable applications, which is based on security bulletins issued by vendors, there's also "shadow list" of vendors and developers that have yet to acknowledge DLL vulnerabilities. ACROS said it's created a dedicated Binary Planting website for tracking these unknown or orphaned vulnerabilities.

From December 2008 to July 2010, ACROS counted at least 66 DLL planting bugs, only 6% of which have been fixed, and 28 EXE planting bugs, none of which have been fixed. Kolsek said that "it is unknown whether the affected applications' authors are aware [of] these vulnerabilities or not."