Mmm, Smells Like 0day

BeyondTrust Research Team, September 17th, 2012

Just when you thought we were out of the woods, Internet Explorer 0day shows up, in the wild. Here’s what you need to know about the vulnerability:

  • Internet Explorer 6, 7, 8, and 9 are vulnerable (UPDATE: Out-of-band patch available now!)
  • Use-after-free when the CMshtmlEd object is deleted and then the same area in memory is used by CMshtmlEd::Exec()
  • Payload delivered via heap spray

It is suspected that this 0day is utilized by the same group that has been using the latest Java 0day to spread the Poison Ivy remote admin tool (RAT). Here’s how the attack is playing out, in the wild:

  • Malicious website hosts exploit.html and determines if target is running IE 7 or IE 8
  • exploit.html loads Moh2010.swf, which then performs a heap spray and loads an iframe
  • Protect.html is loaded and triggers the vulnerability
  • Poison Ivy is then downloaded (111.exe)

Once infected, the payload creates the following files and services:

  • C:WINDOWSsystem32mspmsnsv.dll
  • WmdmPmSN service
The Metasploit module is reliable for IE 7 and IE 8 in Windows XP, but requires the Java Runtime Environment (JRE6 only, the module does not work with JRE7) for exploitation of IE 8 and IE 9 in Windows 7.
Blink and Retina Protection Agent have been verified to succesfully prevent exploitation of this vulnerability through its Application Protection functionality. Additionally, EMET 3.0 helps mitigate exploitation of this vulnerability.
You can detect vulnerable systems using Retina and Retina CS, via the following audit:
17089 – Microsoft Internet Explorer CMshtmlEd::Exec() Code Execution (Zero-Day)
Screenshot of Retina CS Audit 17089

Screenshot of Retina CS Audit 17089