A of antivirus company F-Secure describes receiving the hard drive image of a Syrian dissident's PC which turned out to have been infected with the widely-available 'Xtreme RAT', a backdoor tool for remotely controlling and accessing PCs.

The activist had become infected after accepting a file over a Skype session from a known contact which he believed would help him to hide his PC's hardware MAC address from Government snoopers.

In fact the file, MACAddressChanger.exe, turned out to be malicious and the contact had already been arrested before the call, raising the likelihood that the Syrian Government was behind the attack.

"We have reasons to believe this infection wasn't just bad luck. We believe the activist's computer was specifically targeted," concluded Hypponen after tracing the malware's communication channel back to an IP address controlled by the Syrian national telecoms company.

Earlier in the year anecdotal that the Syrian authorities were using Skype to attempt to penetrate opposition communications using different backdoors, with the Electronic Frontier Foundation (EFF) also reporting Xtreme RAT attacks.