Security watchers have uncovered a new highly targeted email-borne attack that uses a supposed conference invitation as a lure - and disguises extracted data as Microsoft Update traffic.

The spearphishing attempts, which have been levied against several government-related organisations worldwide, try to use alleged unfixed security flaws in Adobe software to implant a Trojan on compromised machines - ultimately opening a backdoor for hackers to take over systems.

Once loaded, the malware also cunningly attempts to escape detection by posing as a benign Windows Update utility. The attack was independently discovered by security researchers from Seculert and Zscaler, who issued a joint warning about the so-called MSUpdater Trojan assault on Tuesday.

"We were able to track similar attacks, from the same group of attackers, back to 2009," Aviv Raff, CTO at Seculert told El Reg.

"The method of operation of many of the attacks is similar – a spearphishing email is sent with a PDF attachment of a fake industry related 'Conference Invitation'. The PDF file exploits zero-day vulnerabilities in Adobe Reader, and then installs the RAT [Remote Access Trojan] malware. The malware tries to stay under the radar of security products by pretending to be a 'Microsoft Windows Update' - hence the name 'MSUpdater' Trojan."

"One variant is using Windows Update-like HTTP requests to communicate with the command-and-control server. The other drops a file named msupdate.exe," he added. "The attacks' purpose was indeed industrial espionage, mainly for stealing intellectual property. One of the main functions of a variant of this malware was to steal specific files and upload them to the C&C server."

Analysis of the attack is ongoing, and Raff is yet to form a clear opinion on the likely perpetrators of the assault.

"We don't have information about the people behind those attacks, however as all of them are targeting government-related organisations, it is highly reasonable to suspect that the attackers are high profile, maybe even a country," he concluded. ®