SesameOp Backdoor Abuses OpenAI Assistants API for C2

# SesameOp Backdoor Abuses OpenAI Assistants API for C2

https://gcdradar.vercel.app/incidents/sesameop-backdoor-abuses-openai-assistants-api-for-c2 · AIR-2025-0070 · closed 2026-01-07

- Lane: Breaches & attacks
- Severity: 3 (Confirmed exploitation)
- Fix status: No fix needed
- First reported: 2025-12-24 (happened 2025-07)
- AI role: AI-enabled attack
- Products: OpenAI Assistants API, SesameOp

## Summary

Threat actors utilized a backdoor implant called SesameOp to abuse the OpenAI Assistants API as a covert command and control channel. The malware fetched commands and exfiltrated encrypted results to maintain espionage persistence.

## What to do

No action recorded; read the sources below and the vendor's advisory.

## Latest updates

- 2025-12-24: SesameOp: Novel backdoor uses OpenAI Assistants API for command and control (https://microsoft.com/en-us/security/blog/2025/11/03/sesameop-novel-backdoor-uses-openai-assistants-api-for-command-and-control)
- 2025-12-24: SesameOp: Novel backdoor uses OpenAI Assistants API for command and control (https://atlas.mitre.org/studies/AML.CS0042)

## Sources

- 2025-12-24 MITRE ATLAS: SesameOp: Novel backdoor uses OpenAI Assistants API for command and control https://atlas.mitre.org/studies/AML.CS0042
- 2025-12-24 Microsoft Security: SesameOp: Novel backdoor uses OpenAI Assistants API for command and control https://microsoft.com/en-us/security/blog/2025/11/03/sesameop-novel-backdoor-uses-openai-assistants-api-for-command-and-control

Verify against the vendor's advisory before changing production. Data CC BY-SA 4.0, https://gcdradar.vercel.app.