APromptRiskDBThreat intelligence atlas
AI Security Technique

AI Agent Tool Poisoning - AI Security Technique

Adversaries may achieve persistence by poisoning tools used by AI agents including built-in tools or tools available to the agent via Model Context Protocol (MCP) connections. This involves compromising benign tools already integrated into the agent's environment. By altering tool behavior such as modifying parameters or descriptions, injecting hidden logic, or redirecting outputs, attackers can maintain long-term...

AI Security TechniquerealizedPersistence

Record summary

A quick snapshot of what this page covers.

Tactics1Attacker goals connected to this method.
Mitigations0Defenses that may help against this attack.
AI risks13Research-backed risks connected to this topic.

Attack context

How this AI attack works in practice.

Adversaries may achieve persistence by poisoning tools used by AI agents including built-in tools or tools available to the agent via Model Context Protocol (MCP) connections. This involves compromising benign tools already integrated into the agent's environment.

By altering tool behavior such as modifying parameters or descriptions, injecting hidden logic, or redirecting outputs, attackers can maintain long-term influence over the agent's actions, decisions, or external interactions. Poisoned tools may silently exfiltrate data, execute unauthorized commands, or manipulate downstream processes without raising suspicion.

ATLAS ID
AML.T0110
Priority score
105
Maturity: realized
Persistence

Mitigations

Defenses that may help against this attack.

No connected defenses. No defense is connected to this attack in the current data.

Case studies

Examples from public reports and exercises.

Poisoned Postmark MCP Server Email Exfiltration

incident
Date2025-09-01

A bad actor successfully exfiltrated emails from users of the Postmark’s MCP server via a supply chain attack. Postmark is an email delivery service that allows organizations to send marketing and transactional emails via API. The Postmark MCP server allows users to interact with Postmark via AI agents.

The bad actor impersonated Postmark, by registering the postmark-mcp package name on npm. They initially published the legitimate versions of the MCP server. After the package became popular and reached over 1,000 downloads per week, the bad actor performed a rugpull and uploaded a malicious version of the package. The malicious version added the bad actor’s email address in the BCC line of all emails sent by the MCP tool. Users who upgraded to this version and continued to use the tool would have all emails exfiltrated to the bad actor.

Source

Where this page information comes from.