Hackers increasingly target browser session cookies rather than passwords. Session cookies are small text files that websites give your browser after you log in, letting you stay logged in without re-entering credentials. If a hacker steals your session cookie, they can access your account without knowing your password.
Between June 2025 and 2026, NordVPN researchers counted more than 52.4 billion stolen cookies in infostealer data. Infostealers are malware programs like Lumma, Vidar, StealC, Acreed, and Atomic Stealer that infect devices through compromised websites, pirated software, and fake installers. Once installed, they extract passwords, PINs, autofill data, and session cookies into files called stealer logs that hackers buy and sell.
Russian Market has become the main dark web marketplace for stealer logs after the FBI shut down Genesis Market in April 2023. DarkOwl threat analysts found approximately 180,000 stealer logs sold on Russian Market in the first half of 2025. Flare Research estimates 90 percent of stealer logs now trade privately on Telegram through automated chatbots, with individual logs selling for $5 to $500 depending on account value.
You can check for compromised accounts in a few ways. Review active devices and locations in your account settings for unrecognized entries. Use Have I Been Pwned, a free service that tracks stolen credentials across dark web forums. NordVPN's Complete or Prime plans include real-time monitoring for hijacked sessions.
If your session cookies are stolen, follow these steps in order. Run a full antivirus scan and clean install your operating system. Reset your email password, enable two-factor authentication, and sign out of all sessions. Sign out of all active sessions on compromised accounts to log out attackers. Change passwords on priority accounts like banking, cloud storage, and password managers. Review third-party app permissions and revoke suspicious access.
Google has begun implementing Device Bound Session Credentials on Chrome for Windows, which locks sessions to a specific device using your computer's security chip. However, no other major online provider currently offers native support for this technology.