Critical Impact: Windows Metafile Flaw a 'Zero-Day Exploit'
Updated: Code for what Secunia is deeming an "extremely critical flaw" in Windows Metafile Format files is being exploited on fully patched systems. Researchers are currently tracking thousands of sites distributing the exploit code.
Context & Ripple Effects
The WMF flaw has gone from bug report to industrialized attack in short order: Secunia rates the Windows Metafile vulnerability "extremely critical," and exploit code is running on fully patched systems. Same-day tracking from Sunbelt counts more than 50 distinct WMF variants in the wild, all riding the same zero-day.
What separates this from a routine bulletin is distribution scale — researchers are tracking thousands of websites serving the exploit, meaning compromise no longer requires a targeted lure, just a browse to the wrong page. With Microsoft's regular patch cycle days away, the pressure is squarely on Redmond to respond outside the calendar.
First-order effects
- Any Windows user on a fully patched system who encounters one of the thousands of tracked sites hosting the exploit code can be compromised with no user interaction beyond viewing the content.
- Security teams must rely on interim measures and detection signatures rather than a vendor patch, while antivirus and IDS vendors race to cover the 50-plus variants already circulating.
Second-order effects
- Antivirus and web-filtering vendors face signature churn at a pace set by the attackers' variant output, shifting near-term value toward firms like Sunbelt and Websense whose tracking feeds give customers hours of warning instead of days.
- Microsoft faces an out-of-band patch decision: waiting for the scheduled cycle leaves the installed base exposed through browsers and file-preview paths, while an emergency release breaks its own testing rhythm.
Third-order effects
- If mass web distribution of format-parser exploits becomes the norm, the monthly patch cadence itself becomes the attack surface's weakest link, pushing vendors toward emergency-release mechanisms and faster disclosure-response norms.
- Rating regimes like Secunia's "extremely critical" label gain market power as triage tools, since enterprises under active exploitation need external severity signals they can act on before the vendor speaks.
The trend: Ubiquitous file-format parsers are becoming mass-exploitation targets, with attacker variant velocity forcing vendors toward faster, out-of-band response cycles.