Where did your extensions go? Google bans 500+ malicious extensions

Google has banned more than 500 extensions from its Chrome Web Store after it was discovered they had been inserting malicious ads into users’ browsing sessions.

While it is uncertain exactly how many times these extensions had been installed, according to ZDNet, who broke the story, the number is likely to exceed 2 million.

In an investigation that began two months ago, independent security researcher Jamila Kaya found that hundreds of extensions were infecting browsers. She teamed with Cisco’s Duo Security team and escalated concerns to Google, which then removed the offending extensions from the store.

The details of the investigation

Kaya used Cisco’s Duo Security extension analyzer tool, CRXcavator, to find that extensions that appeared to be playing by Google’s rules were using advertising to redirect users to certain sites.

In some cases, users were directed to legitimate sites but with an affiliate link so the extensions could get credit for the page visit. In other more nefarious cases, users were sent to a page that infected them with malware or exposed them to a phishing scheme.

Researchers were able to confirm the bulk of these extensions had been operational since January 2019, but it also may be linked to a larger operation going back several years.

According to Duo, this type of “malvertising” operation is on the rise:

Malvertising often occurs within other programs, acting as a vehicle for multiple forms of fraudulent activity, including ad-fraud, data exfiltration, phishing, and monitoring and exploitation. Alternatively, it also emerges in multipart malicious campaigns that involve advertising collection and defraudment.

The prominence of malvertising as an attack vector will continue to rise as long as tracking-based advertising remains ubiquitous, and particularly if users remain underserved by protection mechanisms.

Google moved quickly to take down the offending extensions marked by Kaya, in addition to removing additional ones uncovered in its own investigation.

A Google spokesperson reported to Kaya and the Duo team:

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. We do regular sweeps to find extensions using similar techniques, code, and behaviors, and take down those extensions if they violate our policies.

How can you protect yourself from extension attacks?

There’s not much you need to do to protect yourself from this particular attack: the offending extensions have been removed from the Chrome Web Store.

If you had any of these extensions installed, you’ll find that they no longer open immediately when you try to launch them. Instead, you’ll see a popup notifying you that the extension has been disabled and marked as malicious. You’ll have the option of reactivating the extension — after all, Google can’t uninstall things from your desktop.

That said, be aware that reactivating the extension will expose you to malicious advertising, phishing pages, and/or malware. 

If you suspect that you’ve been exposed to malware from these extensions or other sites, Google has provided a detailed explanation of how to remove unwanted ads, pop-ups, malware, and programs.

The best advice is to only install extensions that come from reputable sources. You can also go a step further to verify the safety of your extensions by installing the Chrome Extension Source Viewer add-on.

To find the extensions that were removed, Duo has compiled a full list.

The best Chrome extensions for marketers

On the other hand, there are tons of content marketing tools that are insanely useful, free, and completely safe. If you’re looking to expand your extension horizons, here are some of my favorites:

• Check My Links: Find broken links on a page
• ColorZilla: Learn the hex code for any color on a page
• GIPHY for Chrome: Easily add giphs to articles and other digital content
• Google Chrome Video Speed Controller: Control the speed at which you watch videos in Google Chrome
• Go Video: Screen and WebCam Recorder: Fire up your computer’s camera for a shareable camera-only or screencast video
• Grammarly for Chrome: Check for errors in Google docs
• Image Size Info: Learn basic info of a web image (e.g., original dimensions, displayed dimensions, file size)
• Page Ruler Redux: Draw a ruler to measure elements on any web page
• Search By Image: Initiate a reverse Google image search
• SEO Quake: Get key SEO metrics of any page or domain
• Word Count Tool: Find the word and character count of selected copy on a page

You’ll find these and many more tools in the Google Chrome Web Store.

Just remember to keep cybersecurity in mind when downloading your next new extension.