ClamWin 0.99 DLL Hijacking
Posted on 08 March 2016
Hi @ll, the executable installer clamwin-0.99-setup.exe (available from <http://www.clamwin.com/download>) loads and executes DWMAPI.dll or UXTheme.dll from its "application directory". For software downloaded with a web browser the application directory is typically the user's "Downloads" directory: see <https://insights.sei.cmu.edu/cert/2008/09/carpet-bombing-and-directory-poisoning.html>, <http://blog.acrossecurity.com/2012/02/downloads-folder-binary-planting.html> and <http://seclists.org/fulldisclosure/2012/Aug/134> for "prior art" about this well-known and well-documented vulnerability. If an attacker places one of the above named DLL in the user's "Downloads" directory (for example per "drive-by download" or "social engineering") this vulnerability becomes a remote code execution. Proof of concept/demonstration: ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 1. visit <http://home.arcor.de/skanthak/sentinel.html>, download <http://home.arcor.de/skanthak/download/SENTINEL.DLL>, save it as UXTheme.dll in your "Downloads" directory, then copy it as DWMAPI.dll; 2. download clamwin-0.99-setup.exe and save it in your "Downloads" directory; 3. execute clamwin-0.99-setup.exe from your "Downloads" directory; 4. notice the message boxes displayed from the DLLs placed in step 1. PWNED! See <http://seclists.org/fulldisclosure/2015/Nov/101>, <http://seclists.org/fulldisclosure/2015/Dec/86> and <http://seclists.org/fulldisclosure/2015/Dec/32> plus <http://home.arcor.de/skanthak/!execute.html> and <http://home.arcor.de/skanthak/sentinel.html> for details about this well-known and well-documented BEGINNER'S error! stay tuned Stefan Kanthak PS: I really LOVE (security) software with such trivial beginner's errors. It's a tell-tale sign to stay away from this snakeoil! Timeline: ~~~~~~~~~ 2016-03-06 sent vulnerability report to authors <security@clamwin.com>: host aspmx.l.google.com[64.233.184.26] said: 550-5.1.1 The email account that you tried to reach does not exist. Please try 550-5.1.1 double-checking the recipient's email address for typos or 550-5.1.1 unnecessary spaces. Learn more at 550 5.1.1 https://support.google.com/mail/answer/6596 y186si9894139wmy.43 - gsmtp (in reply to RCPT TO command) <clamwin@sf.net>: host mx.sourceforge.net[216.34.181.68] said: 550 unknown user (in reply to RCPT TO command) 2016-03-06 report published
