PoC (called CMDExe): http://www.freewebs.com/shreddersub7/htm.htm
Discussion: http://www.freewebs.com/shreddersub7/expl-discuss.htm
------------------Which systems are vulnerable?--------
Any system running any Microsoft Windows XP edition with Internet Explorer 6
or higher, even with SP2 applied.
Any system running any Microsoft Windows Server 2003 edition with Internet
Explorer 6 or higher.
------------------How does this exploit work?-----------
The problem with Internet Explorer is that it doesn't set any restrictions
on web pages that request opening a Windows Help file, compiled with HTML
Help.
Without a restriction, we can (in Internet Explorer) easily command to open
any local web page stored on a victim's computer, including web pages that
are
founded in Windows Help files (with extension .CHM). In this PoC (Proof of
Concept, see below for viewing the PoC), the web page
"alt_url_enterprise_specific.htm" (that is founded in the Windows Help file
"ntshared.chm") will be opened in the HTML Help program "hh.exe".
Since we now opened a web page stored in a Windows Help file (.CHM), it is
possible (thanks to the exploit) to execute a HTML Help control (in this
case, an
ActiveX control) that only fully works in Help files. So in this PoC, we
choosed to launch an ActiveX control for HTML Help. Then, this ActiveX
control will execute
any program we want, in this example that's "cmd.exe".
Thanks to the exploit, it is even possible to add parameters to the executed
program (here: cmd.exe), so that you can easily start malware out of
"cmd.exe". In
this PoC, we added the parameter "/c pause" to the execution code "cmd.exe",
and the result is a DOS Prompt with the text "Press any key to continue. .
.".
To make it complete, the 2 needed programs (Internet Explorer and HTML Help)
will be automatically shutted down after the execution is finished. In this
PoC,
HTML Help and Internet Explorer will be automatically closed after the
execution, without user interaction.
PoC (called CMDExe): http://www.freewebs.com/shreddersub7/htm.htm
Reproduce PoC and discussion:
http://www.freewebs.com/shreddersub7/expl-discuss.htm
--------------How to avoid this exploit...-------------
Since there are no patches from Microsoft available yet, here are some
(temporary?) solutions: Disable Internet Explorer
or disable Active Scripting (HOW?).
OR Use another browser,for example Mozilla FireFox.
More info (like credits, things that are included etc.) about this exploit
can be found at http://www.freewebs.com/shreddersub7/expl-discuss.htm
Contact: ShredderSub7_at_hotmail.com
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