After further investigation, Yahoo found the recent ad malware incident was more widespread than was previously announced.

Earlier, the company reported that some of its ads spread malware that occurred from Dec. 31, 2013 to Jan. 3, 2014 affecting European users. The attack affected more than 2 million PCs and put Yahoo users' personal data at risk.

FoxIT, a Netherlands-based security company, previously announced that UK, France and Romania had the most affected Yahoo users.

However, it seemed that the malware attack was more extensive than Yahoo had claimed. It announced Jan. 10 that the attack might have started Dec. 27, 2013 affecting not only users from Europe but also a small bulk outside the continent.

"Upon further investigation of the recent ad malware incident, we now know that users may have been impacted between December 27, 2013 and January 3, 2014. While the bulk of those exposed to the malicious advertisements were on Europe sites, a small fraction of users outside of this region may have been impacted as well," Yahoo said in a statement on its Help site.

"This attack occurred because an account was compromised, the account has been shut down and we are actively working with law enforcement to investigate this," the company assured.

Yahoo had given the following measures to protect Yahoo user's computers:

  • "Ensure that your computer has the latest patches installed. - http://windows.microsoft.com/en-US/windows/help/windows-update
  • Update to the latest versions of Java and Adobe software.

Java: http://java.com/en/download/updates.xml

Adobe: http://www.adobe.com/downloads/updates.html

  • Use an antivirus application and ensure that it is updated regularly."
RELATED STORIES