Microsoft is warning Windows XP and Server 2003 users that exploit code has been posted online showing attackers how to break into these operating systems remotely via a newly-discovered security flaw.
The vulnerability has to do with a weakness in how Windows Help and Support Center processes links. Both Windows XP and Server 2003 retrieve help and support information from a fixed set of Web pages that are included on a whitelist maintained by Windows. But Google security researcher Tavis Ormandy last week showed the world that it was possible to add URLs to that whitelist.
Microsoft said an attacker could exploit this flaw by tricking a user into clicking a specially crafted link. Any files fetched by that link would be granted the same privileges as the affected system’s current user, which could spell big problems for XP users browsing the Web in the operating system’s default configuration — using the all-powerful “administrator” account.
“Given the public disclosure of the details of the vulnerability, and how to exploit it, customers should be aware that broad attacks are likely,” Microsoft said in a statement released last week.