In case you have missed it, on December 15, 2009 Adobe acknowledged a critical vulnerability in Adobe Reader and Acrobat 9.2 and earlier versions that could cause system crashes and enable an attacker to take control of at-risk systems. Adobe isn't expected to release a patch until January 12. Adobe's advisory is here.
While attacks against this flaw were previously underway, the SANS Internet Storm Center recently analyzed a new attack against this flaw, in depth. The attack code in the malicious PDF is only 38 bytes long. For the blow-by-blow analysis of the flaw, read SANS' analysis here.
I'd expect more attacks to be on the way, both before the January 12 patch, and after. You can't rely on your anti-virus software as, according to SANS, only 6 out of 40 anti-virus vendors detect the exploit code.
So what to do? I'd follow SANS Internet Storm Center's Advice:
If we are to judge the new year by sophistication the attackers started using, it does not look too good.
And, I'd add, don't open PDFs from strangers.
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