Attackers are actively exploiting a vulnerability in all supported versions of Windows that allows them to execute malicious code when targets mount a booby-trapped USB on their computers, Microsoft warned Tuesday in a regularly scheduled bulletin that patches the flaw.
In Tuesday's bulletin, Microsoft officials wrote:
An elevation of privilege vulnerability exists when the Mount Manager component improperly processes symbolic links. An attacker who successfully exploited this vulnerability could write a malicious binary to disk and execute it.
To exploit the vulnerability, an attacker would have insert a malicious USB device into a target system. The security update addresses this vulnerability by removing the vulnerable code from the component.
Microsoft received information about this vulnerability through coordinated vulnerability disclosure. When this security bulletin was issued, Microsoft has reason to believe that this vulnerability has been used in targeted attacks against customers.
The vulnerability is reminiscent of a critical flaw exploited around 2008 by an NSA-tied hacking group dubbed Equation Group and later by the creators of the Stuxnet computer worm that disrupted Iran's nuclear program. The vulnerability—which resided in functions that process so-called .LNK files Windows uses to display icons when a USB stick is plugged in—allowed the attackers to unleash a powerful computer worm that spread from computer to computer each time they interacted with a malicious drive.