Microsoft is working on a fix for a vulnerability in the Server Message Block file-sharing protocol in Windows 7 and Windows Server 2008 Release 2, which could be used to remotely crash a computer. "If exploited, this [denial-of-service] vulnerability would not allow an attacker to take control of, or install malware on, the customer's system but could cause the affected system to stop responding until manually restarted," Dave Forstrom, group manager for public relations at Microsoft Trustworthy Computing, said in a statement.