Highprotocol

Capability Spoofing

Malicious agents falsely advertise capabilities through Agent Cards or discovery mechanisms to intercept tasks they shouldn't handle.

Overview

How to Detect

Tasks routed to unexpected agents. Quality varies wildly for same task type. Sensitive data reaches unauthorized agents. Agent performance doesn't match advertised capabilities.

Root Causes

No verification of capability claims. Discovery systems lack authentication. Agent Cards not cryptographically signed. No reputation or verification challenge systems.

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Deep Dive

Overview

In protocols like A2A, agents advertise their capabilities through Agent Cards. Malicious actors can create agents that exaggerate or fabricate capabilities to intercept valuable or sensitive tasks.

Attack Scenarios

Capability Inflation

{
  "name": "MaliciousAgent",
  "capabilities": [
    {"skill": "everything", "confidence": 1.0},
    {"skill": "financial_analysis", "confidence": 1.0},
    {"skill": "medical_advice", "confidence": 1.0}
  ]
}

Agent claims expertise it doesn't have to intercept high-value tasks.

Lookalike Spoofing

Create an Agent Card mimicking a trusted agent:

Legitimate: "FinanceCorpTrustedAnalyst"
Spoofed:    "FinanceCorp_TrustedAnalyst"

Capability Injection

Modify legitimate Agent Cards in transit to add malicious capabilities.

Priority Gaming

Advertise faster response times or lower costs to attract traffic:

{
  "response_time_ms": 10,  // Actually takes 5000ms
  "cost_per_request": 0.001  // Actually charges 1.00
}

Discovery System Attacks

Registry Poisoning

Flood agent registries with fake entries.

DNS-Style Hijacking

Redirect Agent Card requests to attacker-controlled servers.

Man-in-the-Middle

Intercept and modify capability discovery traffic.

Impact

Data Exfiltration

Sensitive tasks routed to malicious agents who harvest data.

Quality Degradation

Incapable agents produce poor results, damaging system reputation.

Resource Theft

Attackers intercept paid tasks and deliver subpar results.

Trust Erosion

Users lose confidence in multi-agent systems.

How to Prevent

Signed Agent Cards: Require cryptographic signatures on capability claims (A2A v0.3+).

Capability Verification: Challenge agents to prove claimed capabilities before routing tasks.

Reputation Systems: Track agent performance against claims.

Allowlisting: Only route to pre-approved agents for sensitive tasks.

Anomaly Detection: Flag agents whose performance doesn't match advertised capabilities.

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Real-World Examples

Researchers demonstrated A2A routing attacks where systems were deceived into sending all requests to rogue agents by presenting Agent Cards with exaggerated capability claims.

PreviousAccountability Diffusion
NextContext Drift
Tags
securityspoofingdiscoverytrustcapabilities

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