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Researchers Uncover 'GhostPoster' Hiding Malware in Logos of 17 Firefox Add-Ons

The campaign embeds JavaScript in PNG images to quietly deliver a delayed payload that evades routine checks.

Overview

  • The malicious extensions were collectively downloaded more than 50,000 times, according to Koi Security, which identified the 17 affected add-ons.
  • The loader lies dormant for roughly 48 hours and then contacts hardcoded domains, including www.liveupdt[.]com and www.dealctr[.]com, fetching the main payload only about 10% of the time.
  • The final toolkit hijacks affiliate links, injects Google Analytics tracking, strips security headers like CSP and X-Frame-Options, inserts hidden iframes for ad and click fraud, and uses CAPTCHA bypass techniques.
  • The retrieved code is heavily obfuscated with case swapping and base64 and is further protected with a cipher and XOR using a key derived from the extension runtime ID.
  • The add-ons posed as VPNs, translators, ad blockers, and utilities; researchers urge users to remove the listed extensions and consider resetting important passwords, while reports differ on whether the add-ons remain available.