SesameOp backdoor abuses OpenAI Assistants API for C2
🛡️ Microsoft DART researchers uncovered SesameOp, a novel .NET backdoor that leverages the OpenAI Assistants API as a covert command-and-control (C2) channel instead of traditional infrastructure. The implant includes a heavily obfuscated loader (Netapi64.dll) and a backdoor (OpenAIAgent.Netapi64) that persist via .NET AppDomainManager injection, using layered RSA/AES encryption and GZIP compression to fetch, execute, and exfiltrate commands. Microsoft and OpenAI investigated jointly and disabled the suspected API key; detections and mitigation guidance are provided for defenders.
