GhostPoster Malware Found in 17 Firefox Add-ons with 50,000+ Downloads
Dec 17, 2025
Ad Fraud / Browser Security
A new campaign named GhostPoster has leveraged logo files associated with 17 Mozilla Firefox browser add-ons to embed malicious JavaScript code designed to hijack affiliate links, inject tracking code, and commit click and ad fraud. The extensions have been collectively downloaded over 50,000 times, according to Koi Security, which discovered the campaign. The add-ons are no longer available. These browser programs were advertised as VPNs, screenshot utilities, ad blockers, and unofficial versions of Google Translate. The oldest add-on, Dark Mode, was published on October 25, 2024, offering the ability to enable a dark theme for all websites. The full list of the browser add-ons is below - Free VPN Screenshot Weather (weather-best-forecast) Mouse Gesture (crxMouse) Cache - Fast site loader Free MP3 Downloader Google Translate (google-translate-right-clicks) Traductor de Google Global VPN - Free Forever Dark Reader Dark Mode Translator - Google Bing Baidu DeepL Weather...