308. Adversaries Abuse OpenAI Assistants API

Hello everyone!

Today we'll look at another curious example of how adversaries abuse AI to solve various problems, this time they leveraged OpenAI Assistants API.

Microsoft DART uncovered a new malware, SesameOp, which uses OpenAI Assistants API for its command-and-control communications. 

The infection chain consists of a loader (Netapi64.dll) and a NET-based backdoor (OpenAIAgent.Netapi64). Netapi64.dll is loaded at runtime into the host executable via .NET AppDomainManager injection, as instructed by a crafted .config file accompanying the host executable.

So, it's a good hunting idea to look for suspicious connections to api[.]openai[.]com:

event_type: "dnsreqwin"

AND

dns_rname: "api.openai.com"

See you tomorrow!

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