A Chinese security group has released sample code to exploit two new unpatched flaws in Microsoft Windows.
The advisory comes in the week before Christmas, a time when many companies and home users are least prepared to deal with the problems. Security firm Symantec warned its clients of the vulnerabilities on Thursday, after the Chinese company that found the flaws published them to the Internet.
One vulnerability, in the operating system's LoadImage function, could enable an attacker to compromise a victim's PC when the computer displays a specially crafted image placed on a Web site or in an email. The other vulnerability, in the Windows Help program, likewise could affect any program that opens a Help file.
Because the flaws are in a library used by Windows programs, almost all browsers and email clients are likely affected by the flaws, said Alfred Huger, senior director of engineering at Symantec.
"They are rather serious," Huger said. "Both can be exploited by anything that processes images or reads help files."
Because the flaws were accompanied by exploit code that shows how to take advantage of the security holes, Huger expected the exploits to be quickly incorporated into the tools of malicious Internet users.
"The fact that there is an exploit out there is very concerning," he said. "I think you will see it in phishing scams and spyware in very short order."
A mass-mailing computer virus could also quickly begin using the vulnerabilities to spread.
Microsoft could not immediately be reached for comment on the issues.