A weekend spam run tried to dupe recipients into downloading the infamous "Storm Trojan" by attaching files designed to look like videos of a purported missile strike by the US against Iran, antivirus vendors said.
The unsolicited email - which arrives with provocative subject lines including "Missile [sic] Strike: The USA kills more then [sic] 20000 Iranian citizens," "USA Declares War on Iran" and "USA Just Have Started World War III," - also contains attached executable files such as video.exe and readme.exe, said Symantec.
"The underlying threats are actually nothing new," said Symantec researcher John McDonald on the company's security response team's blog. "They are simply minor variants of Trojan.Peacomm and W32.Mixor, which have been repacked in an attempt to avoid existing detection and appear to have been largely successful at that." Symantec added that executable file attached to the war-scare spam is actually a worm that downloads and installs both Trojan horses.
According to data from MessageLabs, Peacomm - also known as Zhelatin - was the most prevalent piece of malware in the past 24 hours. It accounted for 32% of all malicious code being distributed worldwide, said MessageLabs.
By early today, other security companies, including F-Secure, Fortinet, Kaspersky Lab and Sophos, had released updated signatures to detect the tweaked threat.
Peacomm, which also goes by the nickname "Storm Trojan," is notable because an outbreak in January and February ended up claiming the prize as the biggest malware assault since mid-2005.
Previous spam runs of the malware have enticed users with romantic subject headings around Valentine's Day. The malicious code has been spread through blogs and instant messaging as well as e-mail.