Miscreants have wasted no time exploiting a critical hole in Microsoft's Windows Media Encoder. Just four days after Redmond released fixes for that flaw and seven others, security experts found attack code in the wild that preys on users who have yet to install the patch.
Public attack code was published on the Milw0rm exploit list as early as Friday - just three days after Microsoft's Patch Tuesday - though it was dated Wednesday, September 10. By Saturday, honeypots maintained by researchers at Symantec began detecting variants.
"This attack chronology is another example of the rapid adoption of public exploits into widely deployed exploit toolkits," Symantec researcher Sean Hittel writes here.
Attackers are distributing the attacks in at least two different ways. One is through a simple clear-text program on Milw0rm where the sample shellcode has been modified. A second method comes courtesy of a widely deployed toolkit that goes by the name e2, according to Hittel.
e2 appends a first stage-encrypted block to legitimate web pages, causing visitors to be redirected to a second website that launches an attack. The e2 encryptor is similar to later versions of MPack in that it feeds an encrypted block through a two-key decoder.
Symantec doesn't say how widespread the attacks are or how successful they are at actually infecting end-users' PCs. Microsoft has warned that the bug can allow attackers to take complete control of a vulnerable machine, so the smartest course of action is to install right away. To make sure the patch has been applied to your PC go to Start > All Programs > Windows Update. ®