Computer viruses are making a comeback, according to Microsoft’s Director of Trustworthy Computing - with numbers rising globally in 2012.

Tim Rains says that for several years, computer viruses have been “out of favour with attackers”, but points to statistics showing that they have made a comeback in 2012, at least in certain territories.

Writing on the Microsoft Security BlogRains says, “I have rarely seen the virus threat category found on more than 5 percent of systems with detections globally. But more recently I have noticed that viruses seem to be making a comeback.  The relative prevalence of viruses has been trending up.  The prevalence worldwide for the virus threat category was 7.8 percent in the fourth quarter of 2012.”

Rains says that for the past few years, “Viruses simply didn’t support the profit motive many attackers had in the same way that Trojan downloaders and droppers, miscellaneous Trojans, and password stealers and monitoring tools all did.” But new threats designed to steal information are sparking a comeback.

Rains says that computer viruses proliferate in countries with low levels of broadband penetration, such as Egypt, Indonesia and Ethiopia, where software is updated rarely, and infection rates can be as high as 40%.

Pointing to the success of Win32/Sality, a family of polymorphic file injectors found on 8,204,434 computers worldwide, Rains says, “Sality is one of the top five detections on Windows XP.  Sality hasn’t been as successful on newer versions of Windows. Sality’s success proves that file infectors can be still be successful.  Unlike computer viruses from yesteryear, attackers today are trying to steal information, sometimes by turning on computers’ microphones and cameras.”

Rains says that defending against such threats is “relatively easy” - suggesting users update their system software frequently, and also run real-time antivirus, as well as using caution with removable media such as USB sticks and external hard drives.