Google has removed over 500 malicious Chrome extensions from its Web Store following an investigation by a security researcher and Cisco’s Duo Security.
After a two-month investigation, security researcher Jamila Kaya, in collaboration with Cisco’s Duo Security team, identified hundreds of extensions active on hundreds of thousands of Chrome installations that are injecting malicious ads within browsing sessions.
The extensions were part of a huge malware operation, active for at least two years or more, injecting conditionally-activated malicious code and redirecting users to specific sites. In many cases, the sites were actually legitimate, but some destinations were phishing pages, or pages containing malware.
According to the Duo Security report, the browser extension fraud network affected millions of users, and the group behind it was probably active since the early 2010s. To uncover it, independent security researcher Jamila Kaya used CRXcavator – an automated Chrome extension security assessment tool released by Cisco’s Duo Security engineers.
Google responded swiftly to the report and validated findings before fingerprinting the extensions that were identified.
This also allowed its teams to search the full Chrome Web Store and discover more than 500 related extensions.
“We appreciate the work of the research community, and when we are alerted of extensions in the Web Store that violate our policies, we take action and use those incidents as training material to improve our automated and manual analyses,” said a Google spokesperson.
“We do regular sweeps to find extensions using similar techniques, code, and behaviors, and take down those extensions if they violate our policies.”
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