AWS Bedrock: Add Lambda Tool Hijacking Privilege Escalation (Agent Action Groups)

[jFriedli]

Summary

Adds a new AWS Bedrock privilege escalation technique based on Lambda-backed agent tool hijacking.

Details

This PR introduces a misconfiguration scenario where a principal with:

• lambda:UpdateFunctionCode
• bedrock:InvokeAgent

can modify a Lambda function used by a Bedrock Agent action group and trigger its execution via the agent.

Relation to Existing Content

This complements the existing Bedrock privilege escalation technique:

• Code Interpreter Execution-Role Pivot (bedrock-agentcore:StartCodeInterpreterSession + bedrock-agentcore:InvokeCodeInterpreter)

While the existing technique focuses on AgentCore Code Interpreter execution roles, this PR introduces a separate attack surface:

• Bedrock Agents + Lambda action groups
• cross-service trust abuse (Bedrock → Lambda)

No existing content currently documents this vector.

Additional Changes

• Fixed minor markdown formatting issue in the existing mrkdown (```` instead of ```).

References / Creds

• https://www.softwaresecured.com/post/aws-privilege-escalation-iam-risks-service-based-attacks-and-new-ai-driven-bedrock-agentcore-vectors