Security Experts:

Lenovo Provides Instructions for Removing Superfish

Lenovo has apologized to customers for preinstalling Superfish software on their computers. The company has published instructions for removing both the app and the root certificate used for traffic interception.

Superfish’s WindowShopper browser add-on is designed to help users compare prices and find deals based on the images they are viewing. Many Lenovo customers complained on the company’s forum about the application because it injected ads into websites.

However, after a closer analysis, experts determined that this was more than just an annoying piece of adware. The application is believed to pose serious security risks because it injects the ads by installing a local proxy and a self-signed root certificate that enable man-in-the-middle (MitM) attacks against HTTPS connections.

“Superfish replaces legitimate site certificates with its own in order to compromise the connections so it can inject its adverts. This means that anyone affected by this adware cannot trust any secure connections they make,” security researcher Marc Rogers explained in a blog post. “Users will not be notified if the legitimate site’s certificate has been tampered with, has expired or is bogus. In fact, they now have to rely on Superfish to perform that check for them. Which it does not appear to do.”

Rogers has also pointed out that because Superfish uses the same certificate for every website, it would be easy for malicious actors to compromise users’ connections.

Researchers have managed to extract the password and private key for the Superfish certificate. This information can be used to sign potentially malicious websites and software that would be trusted on affected Lenovo devices.

Initially, experts believed Firefox was not affected because it uses its own certificate store. However, the Electronic Frontier Foundation (EFF) discovered 44,000 Superfish MitM certificates in its Decentralized SSL Observatory, an optional feature of the HTTPS Everywhere extension for Firefox, which collects copies of website certificates.

“This either indicates that Superfish also injects its certificate into the Firefox root store, or that on a large number of occasions Firefox users have been clicking through certificate warnings caused by Superfish MITM attacks,” the EFF said.

“Using a MITM certificate to inject ads was an amateurish design choice by Superfish. Lenovo's decision to ship this software was catastrophically irresponsible and an utter abuse of the trust their customers placed in them,” the organization added.

In January, after Lenovo users started complaining about the adware, Superfish disabled server-side interactions on all Lenovo products. Lenovo stopped preloading the software on computers in February, according to a security advisory published on Thursday by the Chinese computer manufacturing company.

According to Lenovo, the problematic application was installed between September 2014 and February 2015 on some E series, G series, U series, Y series, Z series, S series, Flex series, MIIX series, and Yoga series notebooks. The company highlighted that Superfish was not installed on ThinkPad, ThinkCentre, Lenovo Desktop, ThinkStation, ThinkServer, and System x products.

Lenovo has provided instructions on how to remove Superfish. The application itself can be easily uninstalled from the operating system’s control panel, but the certificate is not removed in the process so affected users need to manually delete it by accessing the “Manage computer certificates” option under “Administrative tools.” The company has also promised to provide an app that removes all traces of Superfish from computers.

In an interview with the Wall Street Journal, Lenovo’s chief technology officer, Peter Hortensius, said the company doesn’t want to get into an argument with security researchers. However, Hortensius has noted that the experts are “dealing with theoretical concerns” and there is no indication that anything nefarious has occured.

Users who are unsure if Superfish is installed on their laptops can utilize the online tool developed by Filippo Valsorda, a member of the CloudFlare security team.

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Eduard Kovacs (@EduardKovacs) is a contributing editor at SecurityWeek. He worked as a high school IT teacher for two years before starting a career in journalism as Softpedia’s security news reporter. Eduard holds a bachelor’s degree in industrial informatics and a master’s degree in computer techniques applied in electrical engineering.