Microsoft: Worms Are Most Prevalent Security Problem

The Conficker worm continues to be one of the most prevalent threats facing PCs running Windows, according to a new security report published by Microsoft.

For the first six months of the year, Microsoft found that more than 5 million computers were infected with Conficker, according to its latest Security Intelligence Report.

Conficker spreads either by exploiting a vulnerability in the Microsoft Windows Server service, through infected removable media or brute-forcing weak passwords on other PCs. (See "Conficker Set to Strike: Protect Yourself with These Tips and Tools")

Conficker alarmed Microsoft so much when it appeared that Microsoft issued an emergency patch in October 2008 for the software vulnerability that allowed it to spread rapidly.

The worm is still circulating, mainly in enterprises, said Vinny Gullotto, general manager of the Microsoft Malware Protection Center. Due to its password-cracking ability, if Conficker gets on one PC in a company, it can often then rapidly spread.

Microsoft collects data on infections from its free security products such as Windows Defender, the Malicious Software Removal Tool (MSRT), Security Essentials as well as ones the company sells.

PC World