MCP Security

Definition

MCP Security covers the controls required to safely operate AI agents that use the Model Context Protocol (MCP) — Anthropic’s open standard for giving LLM-based agents access to external tools, data sources, and services. As MCP adoption scales across enterprise estates, securing MCP servers and the traffic flowing through them becomes a distinct security domain.

Aliases / Variants

  • MCP proxy security
  • Agent integration security
  • A2A (Agent2Agent) security — the complementary Google-origin protocol for agent-to-agent communication

Threat Surface

MCP introduces several novel attack surfaces beyond traditional API security:

ThreatDescription
Rogue MCP serverA malicious or compromised MCP server that injects instructions or data into an agent’s context, causing goal manipulation or data exfiltration
Agent Account Takeover (AATO)An attacker hijacks an agent’s session or identity to use it as a proxy for malicious actions — analogous to ATTO (Account Takeover) for human accounts
Prompt injection via MCPMCP server returns a response containing injected instructions that override the agent’s intended behavior
MCP scope creepAgents granted overly broad MCP permissions over time; no governance equivalent to OAuth scope auditing
Data exfiltration through MCPAn agent (or compromised agent) sends sensitive data out via MCP calls to an attacker-controlled server

Required Controls

1. MCP Proxy Layer

An MCP proxy sits between the agent and MCP servers, providing:

  • Traffic inspection for AI-generated and AI-bound payloads (semantic context, not just protocol)
  • Allow-listing of approved MCP servers and endpoints
  • Policy enforcement (block calls to unapproved servers)
  • Logging for forensics and compliance

2. Behavioral Monitoring

Because MCP traffic is semantically rich (natural language + structured calls), monitoring requires agent-specific intelligence overlaid on network/API monitoring. Standard WAF or NGFW rules are insufficient.

3. Threat Intelligence for Agent Traffic

As internet traffic increasingly originates from bots and agents, identifying malicious-agent traffic requires:

  • Enrichment with agent/bot-specific threat intelligence feeds
  • Detection of AATO patterns (session anomalies, unusual call patterns)
  • Filtering of traffic from known-bad MCP servers

4. MCP Governance at Scale

Enterprise estates will accumulate many MCP server registrations. Required capabilities:

  • Inventory and discovery of all MCP servers in use
  • Per-server allow/deny policies
  • Periodic permission reviews (analogous to OAuth token auditing)
  • Incident response playbooks for rogue MCP server scenarios

Relationship to Existing Controls

MCP security is an extension of — but not a replacement for — API security, network monitoring, and AI firewall capabilities. The key differentiation is understanding agent intent: whether a particular MCP call is within the normal operating envelope of the agent, or represents anomalous or malicious behavior.

Standards gap

As of the paper’s publication (Oct 2025), no established standard or framework specifically governs MCP security. OWASP’s Agentic AI threats guidance covers the general threat class; MCP-specific controls are being developed by startups ahead of incumbent tools.

Where It Appears