ChatGPT Custom Instructions: Persistent Data Exfiltration Demo

ChatGPT has a vulnerability where attackers can use image markdown (a way to embed images in text) to trick the system into leaking data. OpenAI recently added Custom Instructions, a feature that automatically adds instructions to every message, which attackers can abuse to install a persistent backdoor (hidden access point) that steals data through the image markdown vulnerability. This technique is similar to how attackers exploit other systems by enabling features like email forwarding after they gain initial access.