Attackers are once again exploiting the public's tendency for not keeping its software updated and its ongoing interest about Iran and its nuclear program to infect users with a backdoor Trojan.

The threat, first flagged and described by security researcher Mila Parkour, comes in an email from a "William Abnett" with "Iran's Oil and Nuclear Situation" in the subject line.

The attached Iran's Oil and Nuclear Situation.doc file contains Flash, which downloads a corrupted mp4 file, which in its turn causes memory corruption and code execution. The attachment takes advantage of a recently fixed Flash bug (CVE-2012-0754).

The file drops and executes the embedded binary (us.exe) in the user's %Temp% directory. The executable is a Trojan that opens a backdoor on the targeted computer and tries to block AV solutions' warnings about its malicious nature.

But since both the DOC and the EXE files are still detected only by a minority of the AV solutions used by VirusTotal, there may not be warnings for it to block.

Parkour warns users to be careful and think twice about opening emails and files sent by people they don't know or organizations they haven't first contacted themselves - email subjects and names of attached malicious files are easily and often changed.