"One of the purchasers of the exploit is involved in the criminal adware/spyware business," read a Kaspersky Lab quarterly report released this week. "It seems likely that this was how the exploit became public."
The WMF flaw unsettled security experts after they found that the virus-writing communitybefore they did. A slew of Trojan programs were written to try and take advantage of the exploit. The British Parliament was who tried to exploit the WMF flaw.
MessageLabs, an e-mail filtering provider for the U.K. government, said last month that targeted e-mails were sent to various individuals within government departments in an attempt to take control of their computers. The e-mails contained the exploit code.
A statement on the Kaspersky Lab site said more than a thousand instances of malicious code were detected in a week. "As the vulnerability was present in all versions of Windows, the situation threatened to spiral out of control."
According to Kaspersky, the situation was mitigated by the holiday season, when Internet use was much lighter than normal.
When the corrupt WMF files finally came to the attention of anti-spyware experts, they were traced back to Web sites known to spread advertising software surreptitiously to computers.
Security companies have lamented the practice by some Web advertisers oftheir software. Some of the more unscrupulous among those are in the business of distributing exploits that let them spread adware without the knowledge of computer users.