Many Lenovo users started complaining last year about a piece of adware being pre-installed on their new computers. After a close analysis, experts have determined that the application poses serious security risks.
The culprit appears to be WindowShopper – Discover Visually, a browser add-on developed by visual search company Superfish. The application analyzes images displayed on Web pages and searches for similar or nearly identical items so that users can compare prices and find deals. The add-on basically injects third-party ads into Web pages.
While many users consider it an annoying piece of adware that came with their brand new Lenovo laptop, security experts claim to have found some even more disturbing behavior that makes the application similar to malware.
The add-on comes with a local proxy that enables man-in-the-middle (MitM) attacks. Even more concerning is that Superfish also installs a self-signed root certificate that enables MitM attacks against HTTPS connections. The application can be easily uninstalled, but the certificate is not removed in the process, experts said.
Mozilla’s Firefox does not appear to be impacted by the MitM issue because the Web browser doesn’t use system certificates.
Superfish could not immediately be reached for comment. Lenovo representatives said they have taken steps to address the issue and pointed out that the problematic application was not installed on all consumer PCs.
“Lenovo removed Superfish from the preloads of new consumer systems in January 2015. At the same time Superfish disabled existing Lenovo machines in market from activating Superfish. Superfish was preloaded onto a select number of consumer models only. Lenovo is thoroughly investigating all and any new concerns raised regarding Superfish,” Lenovo told SecurityWeek.
Mike Shaver, engineering director at Facebook, noted that some users reported in December that the Superfish app had also affected the use of smart card certificates.
Fox-IT researcher Yonathan Klijnsma has managed to extract the private key for the Superfish certificate authority (CA) by reverse engineering the application and trying out possible passwords for the private key. The password is based on the name that Lenovo uses internally for Superfish, the expert said.
“The certificate of this fake root CA is trusted on all sides which means with the private key from Superfish you can man-in-the-middle the client for all websites (unless some specific application uses certificate pinning on a root CA or intermediate f.e.),” Klijnsma told SecurityWeek.
“Removing just the Lenovo software doesn’t fix the issue, the root CA remains in the WIndows trust store. Because I now have managed to gain access to the private key I can MitM any website for Lenovo owners (would they have not fixed the issue or reinstalled the complete operating system of course),” he added.
*Updated with additional information from Yonathan Klijnsma