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Cookie-Bite and Session Hijacking: How Cybercriminals Bypass Passwords

Passwords aren’t the only thing cybercriminals want anymore. Increasingly, attackers are targeting browser session tokens — stealing active sessions to slip past authentication entirely.


One emerging method is the Cookie-Bite attack: a proof-of-concept that shows how a simple browser extension could give attackers access to your business email, cloud platforms, financial portals, and more — without needing your password or triggering MFA.

Here’s everything you need to know about Cookie-Bite, how it works, and how to defend against it.





What Is Cookie-Bite?


Cookie-Bite refers to a proof-of-concept attack where a malicious Chrome extension steals browser session tokens from a victim’s computer.

Session tokens are what keep you logged into websites after authentication. If stolen, they allow an attacker to hijack that session — impersonating you on services like:

  • Microsoft 365

  • Google Workspace

  • Dropbox

  • Salesforce

  • Amazon Web Services (AWS)

  • Banking and payment portals


Importantly:

  • No password needed

  • MFA protections often bypassed

  • No immediate login alerts triggered


Attackers using Cookie-Bite don’t need to phish your login — they quietly piggyback your trusted session instead.





How Cookie-Bite Attacks Work (Step-by-Step)


  1. Victim installs a malicious Chrome extension

  2. The extension quietly accesses Chrome’s local storage

  3. Session tokens for major services are extracted Such as:

    • __Host-3PLSID (Google)

    • SAMLAuthToken (SAML-based apps)

    • MSISAuth (Microsoft login sessions)

  4. Tokens are exfiltrated to the attacker's server

  5. Attacker imports tokens into their own browser

  6. Attacker accesses business services without triggering alerts





What Cyber Attacks Can Follow Session Theft?


Session hijacking through techniques like Cookie-Bite can open the door to a wide range of attacks, including:

  • Business Email Compromise (BEC)

  • Internal Reconnaissance and Cloud Breach

  • Credential Dumping and Privilege Escalation

  • Data Exfiltration and Sale

  • Ransomware Deployment


Cookie-Bite isn’t the final attack — it’s the way in.





Why Cookie-Bite Is So Dangerous


✅ Bypasses passwords — no matter how strong they are

✅ Often bypasses MFA — hijacking happens post-authentication

✅ Hard to detect — sessions look legitimate to systems

✅ Works across many apps — not just email or cloud storage

✅ Easy to deliver — browser extensions are easy to disguise





How to Defend Against Cookie-Bite and Session Hijacking


Limit Browser Extensions to only approved, vetted ones

Monitor Chrome and Browser Behaviour using EDR/XDR

Shorten Session Lifetimes to limit stolen session usability

Use Conditional Access to enforce trust checks

Prompt Reauthentication for Sensitive Actions

Educate Staff on extension risks and session hijacking threats


Need help strengthening your endpoint and session security? Explore our cyber incident response services.





What to Watch for: Indicators of Cookie-Bite-Type Activity


  • Unapproved Chrome extensions installed across devices

  • Logins without normal authentication flows

  • Sessions lasting far beyond normal timeouts

  • Access from strange IPs without password re-entry

  • Missing login alerts where MFA would normally trigger





How STORM Guidance Can Help


✔ Endpoint and browser security reviews

✔ Threat intelligence monitoring for credential and session theft

✔ Cyber incident response if session hijacking is detected

✔ Threat actor engagement for follow-on ransomware or extortion attempts





Stay Ahead of Emerging Cyber Threats


Attacks like Cookie-Bite show that cybercriminals aren’t just after your passwords — they’re after your trusted sessions, too.

Protecting your business requires proactive defence, staff awareness, and quick response if something feels wrong.

For broader support, explore Storm Guidance's threat intelligence and cyber risk services.



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