Cookie Theft Can Bypass Two-Factor Authentication — Here Is How to Stay Safe

Session hijacking via cookie theft has become the fastest-growing identity attack in 2026, with over 2.1 billion stolen cookie records found on underground marketplaces, according to cybersecurity firm SpyCloud. Attackers use infostealer malware — such as RedLine, Lumma, and Vidar — to silently extract browser session tokens, which are then sold on dark web channels for as little as $5 to $30 per victim. Because session cookies represent already-authenticated logins, replaying them in another browser bypasses two-factor authentication entirely, with no password or verification code required. Microsoft confirmed in early 2026 that this technique, often combined with adversary-in-the-middle phishing kits, drove a significant wave of enterprise account compromises, even affecting users with hardware security keys. Experts warn that MFA alone is no longer sufficient protection, urging users to avoid unverified software downloads, use short session timeouts, and monitor accounts for unfamiliar active sessions.