What is Man in the Browser MitB Attack?

Understanding Man in the Browser MitB Attack

Man-in-the-Browser (MitB) attacks represent an insidious threat that bypasses many traditional security controls by compromising the web browser itself—the tool users rely on to access sensitive online services. Unlike network-based attacks that can be blocked by encryption, MitB malware infects the browser or operates as a malicious extension, allowing it to access data after decryption and before encryption. This position gives attackers powerful capabilities: modifying web pages in real-time to inject additional fields that capture sensitive data, altering transaction details (changing recipient account numbers or amounts), capturing credentials even on properly secured websites, and evading multi-factor authentication by hijacking authenticated sessions. These attacks prove particularly dangerous because they occur entirely on the user’s device, making network-based detection ineffective, and they present users with convincing interfaces from legitimate websites. Defending against MitB requires layered controls: keeping browsers updated, restricting extension installations, implementing endpoint detection and response solutions, employing transaction verification separate from the browser, and using behavioral analytics to identify anomalous transactions that might indicate manipulation.