Another wave of malicious browser extensions capable of tracking user activity and compromising privacy have been found across Chrome, Firefox, and Edge, some of which may have been active for up to five years.
The campaign, known as GhostPoster, was identified by Koi Security in December and included 17 Firefox add-ons designed to monitor users’ browsing activity. Threat actors planted malicious JavaScript code in the extension’s PNG logo, which served as a malware loader to retrieve the main payload from a remote server. Researchers at LayerX have found an additional 17 malicious extensions across multiple browsers that have collectively been installed more than 840,000 times.
Ongoing GhostPoster malware campaign
According to the report from LayerX, GhostPoster initially targeted Microsoft Edge and then expanded to Chrome and Firefox. The malicious add-ons may have been active as early as 2020 and include the following:
-
Google Translate in Right Click
-
Translate Selected Text with Google
-
Ads Block Ultimate
-
Floating Player – PiP Mode
-
Convert Everything
-
Youtube Download
-
One Key Translate
-
AdBlocker
-
Save Image to Pinterest on Right Click
-
Instagram Downloader
-
RSS Feed
-
Cool Cursor
-
Full Page Screenshot
-
Amazon Price History
-
Color Enhancer
-
Translate Selected Text with Right Click
-
Page Screenshot Clipper
“Google Translate in Right Click” alone had 522,398 installs. The next most popular add-on was “Translate Selected Text with Google” with 159,645 installs. Researchers also found a more sophisticated variant of the campaign in “Instagram Downloader,” which had 3,822 installs.
GhostPoster malware has built-in safeguards to prevent detection—for example, activation is delayed by 48 hours, and it only communicates with remote attack servers under certain conditions. Once installed, though, extensions that are part of GhostPoster have the ability to hijack affiliate traffic (and redirect commissions to attackers), strip and inject HTTP headers to weaken security, bypass CAPTCHA, and inject iframes and scripts for click fraud and user tracking. The only sort-of good news is that the malware doesn’t harvest credentials or engage in phishing.
While the malicious extensions are no longer available to add in Chrome, Edge, and Firefox, users who have them installed should remove them immediately, as they remain active until explicitly deleted.
