AI agents invoke start_phj_service to trigger actions in Firegex. What it does depends on the arguments the agent supplies, and its effects often reach beyond the immediate call — builds kicked off, notifications sent, workflows started.
Activating a porthijack rule executes a network operation that intercepts and redirects traffic on a specified port. While not permanently destructive, this causes immediate functional changes to network behavior and could disrupt legitimate services or redirect data flows in ways an agent might not intend or fully control.
From the tool's definition 'Activate a porthijack rule' indicates triggering an active network operation that redirects or hijacks port traffic, which is an external operation with real-time side effects.
Attacks that exploit this kind of access
Activate a porthijack rule. It is categorised as a Execute tool in the Firegex MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.
Register the Firegex MCP server in PolicyLayer and add a rule for start_phj_service: 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 Firegex. Nothing to install.
start_phj_service is a Execute tool with high risk. Execute tools should be rate-limited and have argument validation enabled.
Yes. Add a rate_limit block to the start_phj_service 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 start_phj_service. 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.
start_phj_service is provided by the Firegex MCP server (umbra2728/firegex-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Every MCP server has a record like this.
Type a name, get the same breakdown: verified identity, auth posture, risk grade, capabilities, recommended policy.
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