Reports indicate that malicious websites are exploiting multiple vulnerabilities in Microsoft Internet Explorer versions 7, 8, 9, and 10. The vulnerabilities could allow an unauthenticated, remote attacker to execute arbitrary code on a vulnerable system.
Malicious software on attacker-controlled websites leverages an information disclosure vulnerability in Microsoft Internet Explorer to obtain the timestamp from the PE
headers of msvcrt.dll.
The malicious software uses the timestamp value to create additional exploits against the identified system, ensuring better success with additional exploits.
The malicious site then attempts to exploit an additional vulnerability in Internet Explorer that exists because of improper memory operations. The malicious site attempts to exploit this vulnerability and install malicious software on the affected system. The malicious software has been identified as a variant of the Hydraq/McRAT malicious software family as reported by Fireeye
Microsoft has confirmed the vulnerability and software updates are available.
Microsoft has released security bulletin MS13-090 and assigned CVE-2013-3918, as documented in Alert 31635, to this issue.
Microsoft customers can obtain updates directly by using the links in the security bulletin. These updates are also distributed by Windows automatic update features and available on the Microsoft Update service. Microsoft Windows Server Update Services (WSUS), Systems Management Server, and System Center Configuration Manager can assist administrators in deploying software updates.
Users should verify that unsolicited links are safe to follow.
Reports indicate that the memory access vulnerability can be mitigated by the Microsoft Enhanced Mitigation Experience Toolkit