Windows, say experts.
Instead of working it out for themselves, malicious hackers are reverse engineering the patches to better understand the vulnerabilities, said David
Aucsmith, who is in charge of technology at Microsoft's security business and technology unit.
In a keynote speech to the E-Crime Congress organised by Britain's National Hi-Tech Crime Unit, Mr Aucsmith said the tools that hackers were producing
were getting better and shrinking the time between patches being issued and exploits being widely known.
"We have never had vulnerabilities exploited before the patch was known," he said.