An exploit found to be targeting a recently patched vulnerability for Internet Explorer 7 was discovered in-the-wild.  Malware crooks were quick to develop a working exploit for the vulnerability in Internet Explorer 7, which was part of the February Microsoft patch release. Microsoft rated this vulnerability critical with the possibility of a consistent exploit code. The modus operandi bears close resemblance to the zero-day attack using word documents, we blogged about in December 2008.

The attack, delivered in the form of a maliciously crafted document, is sent out to unsuspecting users. This word document contains an embedded ActiveX control which upon opening, connects to a website hosting the MS09-002 exploit.

Malware authors are always working to create new and improved ways to evade detection and control compromised machines. This time, malware authors introduced obfuscation (base64 encoding) possibly to evade easy analysis and detection.

The ActiveX control facilitates connection to the malicious website to launch and execute the MS09-002 exploit.

For those who have not patched their machines, we suggest you install the MS09-002 patch immediately. It will just be a matter of time before different variants of this exploit start circulating in the wild and become incorporated into various Do-It-Yourself web attack toolkits.

The malicious word document is detected with the current DATS as Exploit-MSWord.k and the Internet Explorer 7 exploit is detected as Exploit-XMLhttp.d / Exploit-CVE2009-0075.