Researchers have discovered 17 malicious browser extensions associated with the GhostPoster campaign that have been installed over 840,000 times across Chrome, Firefox, and Edge stores. These extensions are designed to hijack users' browsing sessions and can potentially lead to data theft or other malicious activities. The widespread installation indicates that many users may have unknowingly compromised their security by downloading these harmful extensions. It's crucial for users to regularly check their installed extensions and remove any that seem suspicious. The incident raises concerns about the security measures in place within browser extension stores and the need for more stringent vetting processes to protect users from such threats.