The reach of the Zeus trojan is even more widespread than Microsoft expected when it added detection and removal last week for the pernicious malware.
Last Tuesday, coinciding with the release of its monthly bundle of security fixes, Microsoft added new protection capabilities to its freely distributed Malicious Software Removal Tool (MSRT) to help organizations fight the insidious data-stealing Zeus trojan.
Since then, the tool has cleaned Zeus, also known as Zbot, 281,491 times from 274,873 computers, making it the most prevalent family of malware removed from machines, according to a Sunday blog post.
"Of the 1,344,669 computers cleaned, this is about 1 in 5, a ratio that's higher than we typically see even when accounting for the normal, first-month spike which results from adding a new family [to the tool]," Jeff Williams, principal group manager for the Microsoft Malware Response Center, wrote in a blog post Sunday. "To put this in greater perspective, the removals of Zbot are almost as many as the removals of the #2 and #3 malware families this month combined."
Microsoft estimates that some 86 million computers so have run the latest version of the MSRT.
