Securing AI Agents & MCP Servers: OAuth Delegation (XAA) & Exfiltration Detection

erz — Wed, 28 Oct 2026 22:16:20 +0000

Most MCP (Model Context Protocol) servers deployed today rely on static Service Accounts [00:04:14]. This creates two major flaws: over-privileged agents and zero human accountability in the logs (every action just shows up as svc-ai-agent).

Following recent incidents (Asana MCP, Cline, Salesforce) [00:05:15], we built a lab (Azure APIM, MCP Server, Okta, CrowdStrike) to test two things:

1. Replacing Service Accounts with Delegated Tokens (XAA)

To enforce least privilege down to the MCP server and keep human attribution in the SIEM, we implemented a 3-step token exchange using Cross-App Access (XAA) [00:12:05]:

2. Why IAM isn't enough (Tool-based Exfiltration)

Even with strict token delegation, an agent can still abuse a legitimate tool (like http_request) to base64-encode and exfiltrate secrets the user is allowed to read [00:19:18]. Catching this requires correlating API Gateway prompt inspection (Azure APIM) with SIEM identity & network logs [00:20:34], alongside strict tool sandboxing/whitelisting [00:24:17].

Lab Walkthrough (Video)
(Note: Audio is in French — YouTube English auto-captions work well, and the console/terminal demos are visual).

Direct timestamps to skip the intro:
[00:08:54] — Lab architecture & Service Account vulnerability demo
[00:12:05] — Implementing XAA 3-step token delegation
[00:15:27] — Auth Server scopes & group policies configuration
[00:18:58] — Bypassing IAM: Data exfiltration via http_request tool
[00:20:34] — Catching the leak: Azure APIM prompt inspection & SIEM correlation
[00:23:57] — Limitations: Tool sandboxing & fully autonomous agents

DEV Community: erz

Securing AI Agents & MCP Servers: OAuth Delegation (XAA) & Exfiltration Detection

1. Replacing Service Accounts with Delegated Tokens (XAA)

2. Why IAM isn't enough (Tool-based Exfiltration)