Google removed more than 500 Chrome extensions from the Web Store because, according to the researchers, they were stealing browsing data, and promoting click fraud after installing it on the computers of millions of users.
Depending on how you look at it, this is a good thing because they are no longer available to infect users, but it is also bad considering how easy it is for malicious extensions to go through the Web Store and stay there for years without being detected. Google.
The malicious extensions were found by researcher Jamila Kaya who used the tool CRXcavator Duo Security (available at CRXcavator.io) to detect some suspicious extensions.
Η discovery of extensions was only the beginning, as he had to connect them together to reveal repetitive paterns that could detect other malicious extensions.
So the first thing the researcher noticed was that the codeof each extension often resembled the other's code, a copy with minor changes in the names of the internal functions.
Another similarity was the large number of permissions the extension requested during installation, which allowed them to access browsing data and run when visiting sites using HTTPS.
The researcher, in collaboration with Duo Security, eventually identified 70 extensions that appeared to be related to each other. They all came into contact with similar networks orders and control and appeared to be designed to detect and defeat sandbox analysis.
Many of the extensions have been active for almost a year, while others have been around for much longer.
Google soon after conducted its own investigations with base Jamila Kaya's research and the number of malicious extensions exceeded 500.
Google reported:
We do regular scans to find extensions using similar techniques, codes, and behaviors and remove those extensions that violate our policies.
The extensions discovered by Duo Security and Kaya had been installed a total of 1,7 million times.
Google's Chrome Web has about 190.000 extensions, and this large number may be part of the problem. Malicious extensions can and do hide much more easily from the crowd.
Mozilla Firefox has dealt with the same issue on a smaller scale and recently banned 197 dangerous extensions and reminded everyone that it will no longer tolerate remote code extensions.
If you were using any of the 500 extensions that were removed, you will find that it has been automatically disabled in program of their browsing, with warnings characterizing them as malicious.
What did we learn?
No one can assume that because an extension is hosted on an official web store it is also safe to use:
- Install as few extensions as possible and, despite the above, only from the official web stores.
- Check the comments from others who have installed the extension.
- Pay attention to the developer's reputation and how often they release version updates.
- Pay attention to the permissions requested by the extension (Chrome, Settings - Extensions - Details) to see if they match the features of the extension.
