When Microsoft released a security advisory detailing a critical flaw in Microsoft XML Core Services and its corresponding “Fix it” mitigation solution last week, it made sure to note that it was aware of the flaw being misused in “active attacks”.
Now, less than a week later, the Metasploit exploit framework has been fitted with a module that takes advantage of the vulnerability, meaning that the attack option is also freely available to anyone who knows how to use the framework.
The flaw itself affects Microsoft XML Core Services 3.0, 4.0, 5.0, and 6.0, and consequently affects all supported versions of Windows, and all supported editions of Office 2003 and Office 2007. It allows attackers to perform remote code execution on a target’s computer if the target is careless enough to land on a specially crafted webpage by using Microsoft’s Internet Explorer browser.
Luckily for those users who aren’t logged in as administrators, the vulnerability allows the attacker to gain the same user rights as the logged on user, but not to escalate privileges.
Still, users are advised to protect themselves by implementing the offered (temporary) Fix it solution.