McAfee said that the Google hackers used an unknown exploit in Internet Explorer.
Thursday McAfee said that Operation Aurora, the attack that hit Google and multiple companies early in the week, was the result of a new, "not publicly known" vulnerability found in Microsoft's web browser, Internet Explorer. McAfee said that it has informed Microsoft with its findings, and that Microsoft is expected to publish an advisory on the matter soon.
"As with most targeted attacks, the intruders gained access to an organization by sending a tailored attack to one or a few targeted individuals," said McAfee's George Kurtz in this official blog. "We suspect these individuals were targeted because they likely had access to valuable intellectual property. These attacks will look like they come from a trusted source, leading the target to fall for the trap and clicking a link or file. That’s when the exploitation takes place, using the vulnerability in Microsoft’s Internet Explorer."
Kurtz said that the malware opens a back door once it's downloaded and installed, allowing the attacker to "perform reconnaissance" and gain complete control of the compromised system. Once that takes place, the attacker can identify "high value targets" and siphon off valuable data from the targeted company.
Kurtz also said that although McAfee identified the Internet Explorer vulnerability as one of the attack vectors, he said that there could be additional vectors not yet discovered. According to their findings, Adobe Reader is not one of these vectors despite other reports blaming Adobe as a culprit. More information on the Internet Explorer vulnerability and Operation Aurora can be found on the McAfee blog.