Threat Type: Malicious Web Site / Malicious Code
Websense® Security LabsTM has received reports of exploits circulating in the wild that take advantage of a serious Windows vulnerability. Microsoft just released an out-of-band patch to address this just hours ago (see MS08-067).
The remote code execution vulnerability is found in netapi32.dll, and carries a severity rating of “Critical” by Microsoft, affecting even fully patched Windows machines. This vulnerability (CVE-2008-4250) allows malicious hackers to write a worm (self-propagating malicious code without need for any user interaction), by crafting a special RPC request. A successful exploitation would result in the complete control of victim machine.
To date, we have seen attacks installing a Trojan (Gimmiv) upon successful exploitation. At the time of this alert, only 25% of 36 anti-virus vendors could detect this malicious code. Blocking TCP ports 139 and 445 at the firewall is only a partial solution because most desktops have file/printer sharing turned on. The out-of-band patch release by Microsoft testifies to the severity of this vulnerability and the urgency for an immediate fix.
Websense is monitoring the development of this attack, and has classified the corresponding Web sites and malicious code that the exploit downloads.