put_user_policy
AI agents use put_user_policy to create or update resources in Amazon MQ MCP Server — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your Amazon MQ MCP Server environment.
This tool creates or modifies IAM user policies, which is a Write operation (reversible via update/delete). Severity is high because misconfigured policies could grant excessive permissions to AWS resources. However, it is not Destructive since policies can be removed, and not Execute since it doesn't run arbitrary operations.
From the tool's definition Tool name 'put_user_policy' combined with sibling tool 'add_inline_policy' indicates IAM policy creation/modification. The 'put_' prefix and 'user_policy' subject imply creating or updating user-attached policies. Tool description is empty, limiting evidence.
Attacks that exploit this kind of access
put_user_policy. It is categorised as a Write tool in the Amazon MQ MCP Server MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.
Register the Amazon MQ MCP Server MCP server in PolicyLayer and add a rule for put_user_policy: allow, deny, rate-limit, or require approval. Point your MCP client at the PolicyLayer proxy URL and the rule is enforced on every call, before it reaches Amazon MQ MCP Server. Nothing to install.
put_user_policy is a Write tool with medium risk. Write tools should be rate-limited to prevent accidental bulk modifications.
Yes. Add a rate_limit block to the put_user_policy rule in your PolicyLayer policy. For example, setting max: 10 and window: 60 limits the tool to 10 calls per minute. Rate limits are tracked per agent session and reset automatically.
Set action: deny in the PolicyLayer policy for put_user_policy. The AI agent will receive a policy violation error and cannot call the tool. You can also include a reason field to explain why the tool is blocked.
put_user_policy is provided by the Amazon MQ MCP Server MCP server (awslabs.amazon-mq-mcp-server). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.