Microsoft said Friday that it inadvertently shipped the Nimda computer virus with the Korean version of its Visual Studio .Net developer tools.
No customer systems were infected by the virus, and the risk of infection is low, a company spokesman said.
"The risk is low, but we're taking this very seriously," he said.
Nimda became an unwelcome bonus with the Korean version of Visual Studio .Net through the localization process, in which Microsoft contracted with a third party to translate the application to Korean, he said.
Because Visual Studio .Net doesn't recognize the existence of the file infected by Nimda, the risk of infection is low, he said. Also, the program requires Internet Explorer 6, which is protected against the virus.
Korea makes up less than 1 percent of Microsoft's customer base, the spokesman said, but he declined to specify how many of the flawed software copies were shipped.
He said Microsoft discovered the problem in mid-May and conducted an investigation that ensured no other language versions of Visual Studio .Net were affected by the virus. The company has since updated its review process to ensure the problem does not happen again, he said.
Microsoft issued an update to remove infected files from the program and also offered Korean developers replacement programs.
Nimda, which appeared last September, infected thousands of computers through multiple infection methods.