Cyberattacks usually start with phishing emails or weak passwords.
This one did not.
Security researchers recently uncovered malicious browser extensions stealing ChatGPT session tokens. These extensions looked harmless. Some were even available in official extension stores. Once installed, they quietly took over active ChatGPT sessions without triggering alerts.
No fake login page. No stolen password. No MFA prompt. This attack runs silently.
What’s Happening Here
The malicious extensions used a simple technique. They monitor browser activity, capture active ChatGPT session tokens when it’s launched, and send those tokens to attacker-controlled servers.
Session tokens prove you are logged into a website. Think of them as a master key. If an attacker has your session token, they do not need your password. They access the account as if they are you, until the session expires or is revoked.
Session tokens are revoked when you “log off” important websites instead of closing the browser tab.
Why Session Tokens Matter So Much
A session token works like a wristband at a concert. Once you have it, security stops checking your ticket. Everyone assumes you are authorized to be there. If someone steals your wristband, they walk right in. No questions asked. However, in the real world, if you notice your wristband is missing, you can report it stolen. In the digital world it’s an exact copy of your valid token and you have no idea its been stolen. This makes these attacks more dangerous and difficult to identify until it’s too late.
This is why session token theft is becoming more common than password theft. It bypasses many traditional security controls without setting off alarms.
Why Session Tokens Create New Challenges
When you log into a website, the system gives your browser a session token. This token tells the website “this person already authenticated.” The website stops checking your password every time you click a link.
If someone steals that token, they walk right in. You still have yours and it works fine. The attacker has an exact copy. You will not notice it was stolen until something goes wrong.
This is why session token theft is becoming more common than password theft. It bypasses traditional security controls without setting off alarms.
Why Browser Extensions Deserve More Attention
Browser extensions are built to be useful. Many request permission to read everything you do online, modify web pages, and access cookies or session data. People often click Allow without reviewing whgat they are agreeing to. IT often do not monitor or block extension installs.
Once installed, extensions run in the background. They do not log out. They can monitor everything you’re doing, where you’re going, what you’re asking AI to do for you. That persistence makes them very attractive to attackers.
Why this Matters for your Business
This is not just about personal accounts. In a work environment, a compromised browser exposes more than one account. Attackers may read internal AI conversations, steal sensitive data, prompts, and plans.
If your team uses AI tools at work, browser security is now an important threat vector to be addressed.
How to Reduce the Risk
The good news is this risk is manageable when technical controls and user awareness work together.
Start by removing browser extensions that are no longer used. If an extension is not required for daily work, it should not be installed. In managed environments, restrict extensions to an approved allowlist using Group Policy, MDM tools like InTune, or even purpose-built browser security tools.
IT teams should prevent unauthorized extension installation using centralized controls. This can include:
- Removing local administrator rights from end users
- Enforcing browser extension allowlists via Group Policy or MDM
- Blocking installs through PowerShell automation or endpoint management tools
- Disabling developer mode in browsers to prevent sideloaded extensions
Treat browsers as identity platforms, not simple web tools. They store session tokens, credentials, and access to SaaS platforms. Apply the same security standards used for endpoints and servers.
Teach users to review extension permissions carefully. Any request to read or change data on all websites should trigger caution. Encourage users to install extensions only from trusted publishers and approved internal lists.
Finally, assume at least one extension will eventually be malicious and design controls to detect and contain the impact quickly. Endpoint Detection and Response (EDR) tools are a strong line of defense, especially when combined with default-deny application and extension policies.
The Bigger Takeaway
This story is not really about ChatGPT. It is about how our work life has changed.
Browsers are now the front door to your business, and attackers know it. Security strategies that stop at passwords, MFA, and even the latest Passkeys, are not enough to prevent session token attacks.
The real security battle is no longer at login. It is protecting identity, sessions, and access after authentication succeeds.
Take One Step Today
Review your browser extensions this week. Remove anything you do not recognize or use regularly. If you manage IT for your organization, start building an approved extension list. If you are an employee, ask your IT team if they have extension policies in place.
Small steps build safer habits. You do not need to fix everything at once. You need to start somewhere, and browser hygiene is a smart place to begin.
Additional Resources
- SC Media: Researchers find 16 browser extensions stealing ChatGPT session tokens
- Venn’s Enterprise Browser Security Guide
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The post Sneaky Browser Extensions Are Hijacking ChatGPT Sessions appeared first on CyberHoot.
