Crackers latch onto year-old Windows token vuln

Unpatched bug features in multi-stage attacks

Hackers have created exploits against a long-standing, unpatched Windows "token kidnapping" vulnerability.

The appearance of attacks follows a year after security researchers Cesar Cerrudo informed Microsoft of the problem in March 2008. Microsoft acknowledged the potential issue in April and published workarounds in an advisory. A more comprehensive fix is yet to appear.

The privilege escalation flaw exposed by the vulnerability is subtle and not easily exploitable, so Microsoft can arguably be forgiven for treating the security bug as less than critical and not rushing out a fix. That rationale becomes redundant, however, once a flaw gets used in attacking real systems, as in this case.

Microsoft Windows XP, Vista, and Server 2003 and 2008 systems are all potentially vulnerable.

Cerrudo followed up his initial March advisory with the publication of proof of concept code in October, a move that would normally stir the software giant into producing a patch, though not in this case.

More recently hackers begun taking advantage of the vulnerability in attempts to pry open vulnerable systems. The flaw has cropped up in blended (multi-stage) attacks, the SANS Institute's Internet Storm Centre reports. ISC handler Bojan Zdrnja describes the case as an incident where web application security, Microsoft, and the anti-virus vendors have all played a stinker.

Other security watchers are more inclined to blame Redmond.

"This is yet another example of a black-eye that Microsoft could have avoided. To repeat, the company had notice about this issue one year ago and despite evidence of proof-of-concept code, there is no patch for affected Windows users," writes security blogger Ryan Naraine, who doubles up as a security evangelist at Kaspersky Lab. ®

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