Microsoft has introduced a "fairly major" update to its Malicious Software Removal Tool to detect and kill infections of the insidious and constantly morphing data-stealing malware family known as Zbot, or Zeus. Since the software giant first added detection for Zeus last October, hundreds of thousands of Windows PCs have been expunged of the threat, prominent in banking and e-commerce fraud. But as Zeus, which recently merged code bases with SpyEye, continues to acquire advanced evasion capabilities, Microsoft has had to fight "sneakiness with sneakiness," according to a blog post on Wednesday. The company introduced the update as part of its monthly security patches, released on Tuesday.