Agent-in-the-Middle — A2A protocol spoofing via fake agent cards
Date: 2025-04
Affected: Agent-2-Agent (A2A) protocol — multi-agent workflows
Attack vector: rce
Category: research-demonstrated
Severity: Critical

Malicious agent published fake agent card in open A2A directory falsely claiming high trust. LLM judge agent selected it, enabling rogue agent to intercept sensitive data and leak to unauthorized parties.

Impact: Data interception; trust violation; cascading agent compromise

Mitigations:
Agent card signing and validation
Cryptographic agent identity verification
Multi-factor trust assessment (not just self-declared)

Architectural layers (MAESTRO):
label: Agent Ecosystem
notes: Fake agent card published in open directory
role: origin
label: Agent Frameworks
notes: LLM judge trusts falsified trust claims
role: propagation