The Rise of Agent Networks: A New Security Frontier
Emerging Agent-to-Agent (A2A) frameworks have emerged to support organizations as they move from isolated AI applications to interconnected networks of autonomous agents. A2A enables software agents to discover, authenticate, and collaborate across organizational boundaries, unlocks unprecedented automation capabilities. A2A also introduces an expanded attack surface, and begs the question: how do we secure communications between machines that operate beyond human oversight? Today, Cisco introduces the A2A Scanner: an open-source security framework designed to protect the integrity of autonomous agent networks and secure the A2A protocol stack.
Understanding A2A and Why It Matters
The A2A protocol defines a standardized mechanism by which agents (that may have been built on different models or platforms) can communicate and work together. For example, a data-analysis agent may delegate results to a visualization agent, forming efficient end-to-end workflows. Machine-to-machine communications operate at rates that are often faster than humans can keep up with. This creates a need to develop secure and standardized methods to confirm that agents operate within defined boundaries.
Threats that can emerge in an A2A environment are manifold, and can include Agent Card spoofing, task replay, privilege escalation across agents, and artifact tampering:
- Trusted Agent Impersonation (Spoofing): Malicious agents may represent themselves as trusted identities to extract sensitive information or gain privileges.
- Indirect Prompt Injection Attacks via Streams: Hidden commands or manipulations can be embedded in live data streams (like Server-Sent Events) and hijack agent behavior.
- Capability Inflation: An agent may request or grant permissions—such as file access or network calls—that extend beyond its intended scope.
- Decision Paralysis & Resource Exhaustion (Denial of Service): Malicious or misconfigured agents may trap other agents in infinite loops, resource-draining tasks, or cascading failures leading to service degradation or complete denial of service.
To build multi-agent systems that are safe and trustworthy, developers need tools that verify agent identity, behavior and compliance in real time.
Introducing the A2A Scanner
Cisco’s A2A Scanner is an open-source security framework that validates agent identities and inspects their communications for threats. Traditional API security tools miss many of the nuanced risks inherent in autonomous agent interactions such as Agent impersonation or Prompt injection Via Agent Cards. Our A2A scanner integrates static analysis of agent definitions (e.g., metadata, manifests, Agent Cards) with dynamic runtime monitoring of communications between agents, enabling a multi-layered defense strategy.
Our scanner leverages five distinct detection engines to work cohesively and provide defense-in-depth coverage: pattern matching with detection signatures, protocol validation with specification compliance, behavioral analysis with heuristics, runtime testing with an endpoint analyzer, and semantic interpretation with an LLM analyzer.
Let’s examine our specification compliance engine in particular to discuss its value to threat detection and broader organizational security strategies. As organizations build agent registries, marketplaces, and federated agent ecosystems, they face a fundamental challenge: how can they account for every agent entering their ecosystem and confirm that agents are well-formed, properly configured, and ready to interoperate with others? Without these checks, we could have cascading failures across the registry.
The specification compliance analyzer addresses agentic security risks by validating agents against the official A2A protocol specification. Agent registries can then flag potential security threats, and also surface conformance issues such as missing required fields, invalid data types, malformed URLs, or improperly structured capabilities. If agents are missing critical metadata or violates protocol standards, they can still cause integration failures or unpredictable behavior downstream.
For agent registry operators, this means the ability to enforce quality gates at registration time, generate compliance reports for governance, and check that every agent in the ecosystem meets a baseline standard of implementation quality. It transforms the scanner from a pure security tool into an enabler of trusted, interoperable agent networks.
Cisco’s Approach to AI Security: Building Confidence in Autonomous Systems
The A2A Scanner complements Cisco AI Defense, Cisco’s comprehensive platform for AI lifecycle security. While AI Defense covers AI models and applications, the A2A Scanner focuses specifically on the “mesh” of communication between autonomous systems. Organizations can audit agent registries and flag malicious or non-compliant agents before deployment to verify that third-party agents integrated into business workflows meet enterprise-grade security and compliance standards. The Scanner also supports zero-trust agent architectures, where every agent interaction is programmatically validated against its declared capabilities and security policies.
AI is moving towards an agentic future, and at Cisco, we want to help ensure that organizations can trust those systems. Our A2A Scanner gives developers and security teams the visibility and control they need to adopt autonomous agent systems safely. As A2A standards and agent capabilities evolve, Cisco will continue advancing this tool to stay ahead of new threats—ensuring your agent networks remain helpful, secure and trustworthy.
Get Started
Cisco’s A2A Scanner is open-source and available today. You can explore the code, run an interactive demo, and contribute to the project on GitHub.
We welcome contributions from security researchers, AI developers, and the broader community. Visit the A2A Scanner Repository on GitHub and begin securing your agent networks now.
