attach_group_policy
AI agents use attach_group_policy to create or update resources in AWS — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your AWS environment.
Attaching a policy to a group modifies access control by granting permissions to all group members. This is a reversible Write operation (policies can be detached), but has high severity due to potential privilege escalation and wide blast radius across all users in the group. Not Destructive because the action is reversible; not Execute because it doesn't run arbitrary code.
From the tool's definition Tool name 'attach_group_policy' indicates attaching (modifying/adding) an IAM policy to a group. Context from sibling tools shows this is an AWS IAM management server ('add_user_to_group', 'attach_user_policy').
Documented attack patterns abuse exactly the kind of access attach_group_policy gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and AWS, and nothing reaches the server without passing your rules. This is the rule we recommend for attach_group_policy:
{
"version": "1",
"default": "deny",
"tools": {
"attach_group_policy": {
"limits": [
{
"counter": "attach_group_policy_rate",
"window": "minute",
"max": 30,
"scope": "grant"
}
]
}
}
}attach_group_policy stays usable, but capped — an agent stuck in a loop can't make hundreds of changes a minute. Everything else on the server is denied unless you say otherwise.
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attach_group_policy. It is categorised as a Write tool in the AWS MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.
Register the AWS MCP server in PolicyLayer and add a rule for attach_group_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 AWS. Nothing to install.
attach_group_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 attach_group_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 attach_group_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.
attach_group_policy is provided by the AWS MCP server (@awslabs/mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Start from AWS, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.
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300 AWS tools catalogued and risk-classified — across an index of 43,000+ MCP servers.