Porn worm extorts money from 2,500 victims

A fast-spreading Russian ransom worm that locks people out of their files has found at least 2,500 victims willing to pay up to get back control of their PCs, researchers have discovered.

The malware is identified by Trend Micro as Worm_Rixobot.A, which says it has been spreading in recent weeks using infected porn websites, instant messaging applications and even infected USB drives, hence its designation as a worm rather than a Trojan.

After taking over a user’s PC, terminating a range of Windows and security programs and blocking access to websites, a splash screen demands that users pay the Russian rouble equivalent of $12 by texting a premium-rate SMS number in order to receive an unlock key.

The relatively small sum involved and the use of a simple payment channel might explain why the con appears to be working. According to Trend, which hacked the crime servers associated with the worm, the latest campaign has made 901,000 RUR (about $29,500) in only five weeks, equivalent to nearly 2,500 people having paid the ransom.

The true number of victims could be much higher. The company also found that the initial file that starts the infection was downloaded 137,000 times during December alone, mostly by users in Russia. Over 3,000 downloads were reported for UK users.

Unlike recent examples of ransomware such as GpCode, Rixobot.A doesn’t resort to complex file locking techniques such as encryption in order to extort sums of up to $150 from its victims. But because it doesn’t demand more than a few dollars, it probably doesn’t have to. Many victims will probably just pay up to avoid the inconvenience.