Zombies Still Haunt Windows PCs

CORRECTED: Software giant Microsoft  has crowned the “zombie” PC the greatest threat to Windows users.

Of the many forms of attacks uncovered during the first half of 2006, the company said backdoor Trojans which take control of infected computers can be found in almost one out of every two Windows-based systems.

“Attackers, with financial gain in mind, are clearly concentrating a significant amount of development focus on this category of malware,” according to Microsoft’s Security Intelligence Report, which covers January through June.*

The results were gathered from use of the software maker’s Windows Malicious Software Removal Tool (MSRT). The numbers reflected only Windows computers which used MSRT that were infected by a Trojan.

More than 43,000 new versions of the malicious software were found making Trojans that turn PCs into cash cows for hackers “the most active category of malware,” according to the report.

The news comes as a 32-year-old Florida man was charged with using an army of bots to launch a distributed denial of service (DDOS) attack against Akamai Technologies.

Of the four million Windows machines that used the MSRT, nearly two million contained at least one backdoor Trojan.

While 50 percent seems high, the results are actually an improvement over last year, when 68 percent of computers had a backdoor Trojan.

While Microsoft said backdoor Trojans dominated security threats, rootkits, which garnered publicity for their ability to open a door for malicious behavior, actually fell by 50 percent over the past six months.

Although the results come as little surprise to security vendors closely watching the growth of zombies armies of PCs, the news may wake up a few consumers.

“The big brands they count on are missing this stuff,” Ross Brown, CEO of Eeye Digital Security, told internetnews.com.

The Microsoft report “throws the AV people under the bus,” Brown said.

While many attackers have developed exploits that circumvent commonly used antivirus tools, the malicious code was caught by Microsof, simply because it was introduced only in January of last year.

The report comes on the heels of a dispute between Microsoft and security vendors over what they view as a lockout by the upcoming Vista operating system.

*Microsoft’s results reflect only the Windows PCs that used MSRT and discovered Trojan software from January 2006 to June 2006.