OpenAI quickly fixed account takeover bugs in ChatGPT

OpenAI addressed multiple severe vulnerabilities in the popular chatbot ChatGPT that could have been exploited to take over accounts.

OpenAI addressed multiple severe vulnerabilities in ChatGPT that could have allowed attackers to take over user accounts and view chat histories.

One of the issues was a “Web Cache Deception” vulnerability reported by the bug bounty hunter and Shockwave founder Gal Nagli, it could lead to an account takeover.

The expert discovered the vulnerability while analyzing the requests that handle ChatGPT’s authentication flow. The following GET request caught the attention of the expert:

https://chat.openai[.]com/api/auth/session

“Basically, whenever we login to our ChatGPT instance, the application will fetch our account context, as in our Email, Name, Image and accessToken from the server, it looks like the attached image below” Nagli wrote on Twitter detailing the bug.

The expert explained that to exploit the flaw, a threat actor can craft a dedicated .css path to the session endpoint (/api/auth/session) and send the link to the victim. Upon visiting the link, the response is cached and the attacker can harvest the victim’s JWT credentials and take full control over his account.

Nagli praised the OpenAI security team that quickly addressed the issue by instructing the caching server to not catch the endpoint through a regex.

The bad news is that the mitigation implemented by the company only partially addressed the issue. The researcher Ayoub Fathi discovered that it is possible to bypass authentication targeting another ChatGPT API. An attacker can exploit this bypass technique to access to a user’s conversation titles.

“GET /backend-api/conversations%0A%0D-testtest.css?offset=0&limit=20 Send it to a victim, and upon accessing it – his own “API” response will be cached, and if you recheck the same URL (i.e. fetching the cached response of the victim), you will be able to see the victim’s HTTP response, which contains the conversations’ titles.” explained the expert Ayoub Fathi on Twitter.

The expert pointed out that all ChatGPT APIs were vulnerable to the bypass, which means that an attacker could exploit the issue to read conversation titles, full chats, and account status.

Fathi reported the issue to OpenAI which quickly addressed it.

Unfortunately for the researchers, OpenAI has yet to run a bug bounty program to reward researchers that report vulnerabilities in its chatbot.

On Friday, OpenAI revealed that the recent exposure of users’ personal information and chat titles in its chatbot service was caused by a bug in the Redis open-source library.

The company identified the bug and quickly addressed it.

“We took ChatGPT offline earlier this week due to a bug in an open-source library which allowed some users to see titles from another active user’s chat history. It’s also possible that the first message of a newly-created conversation was visible in someone else’s chat history if both users were active around the same time.” reads an update published by the company.

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Pierluigi Paganini

(SecurityAffairs – hacking, ChatGPT)

Pierluigi Paganini

Pierluigi Paganini is member of the ENISA (European Union Agency for Network and Information Security) Threat Landscape Stakeholder Group and Cyber G7 Group, he is also a Security Evangelist, Security Analyst and Freelance Writer. Editor-in-Chief at "Cyber Defense Magazine", Pierluigi is a cyber security expert with over 20 years experience in the field, he is Certified Ethical Hacker at EC Council in London. The passion for writing and a strong belief that security is founded on sharing and awareness led Pierluigi to find the security blog "Security Affairs" recently named a Top National Security Resource for US. Pierluigi is a member of the "The Hacker News" team and he is a writer for some major publications in the field such as Cyber War Zone, ICTTF, Infosec Island, Infosec Institute, The Hacker News Magazine and for many other Security magazines. Author of the Books "The Deep Dark Web" and “Digital Virtual Currency and Bitcoin”.