More than 50 WMF variants in the wild using zero day exploit
What does this mean? — BlogThis! — WEDNESDAY, DECEMBER 28, 2005 — More than 50 WMF variants in the wild using zero day exploit — Sunbelt researches have come across more than 50 new variants of the Windows Metafiles (WMF) using the new zero day exploit.
Context & Ripple Effects
Sunbelt researchers' count of 50-plus WMF variants turns what eWEEK framed that same day as a critical Windows Metafile zero-day into an active campaign rather than a single proof-of-concept: attackers are mass-producing distinct files against one unpatched Windows flaw, and the parallel pickup by Websense and eWEEK shows the security industry treating it as a top-tier incident.
The significance is the gap the variant flood opens — each new file can slip past signature-based antivirus until vendors catch up, leaving Windows users exposed through image previews with no vendor fix available as of December 29, 2005.
First-order effects
- Antivirus vendors are forced into a signature treadmill, releasing detection updates per variant while Sunbelt's count of 50-plus means many machines remain unprotected between definition pushes.
- Windows users browsing or previewing untrusted images face direct compromise risk, since the exploit runs against a flaw Microsoft has not yet patched.
Second-order effects
- Inconsistent detection across AV engines pushes enterprises toward unofficial mitigations and third-party hotfixes ahead of any Microsoft patch, fragmenting the response.
- Microsoft faces mounting pressure to break its patch cycle with an out-of-band release, since waiting for a scheduled update leaves the zero-day window open while variants multiply.
Third-order effects
- If exploit code keeps circulating before a vendor fix exists, the incident strengthens the case that signature-based defenses alone cannot hold against fast-replication attacks — shifting security budgets toward behavior-based and host-level controls.
- A market for working zero-days against unpatched Windows components points toward exploit distribution becoming an organized underground economy rather than isolated researcher disclosures.
The trend: Malware campaigns are shifting from single exploits to rapidly re-varianted attacks that outrun signature-based antivirus, exposing the lag between discovery and vendor patch.