Spawn a command with proxy env vars pre-configured (HTTP_PROXY, HTTPS_PROXY, SSL_CERT_FILE, NODE_EXTRA_CA_CERTS, CURL_CA_BUNDLE, and 15+ more). Traffic automatically routes through the MITM proxy.
AI agents invoke interceptor_spawn to trigger actions in Proxy. 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.
This tool executes arbitrary shell commands/processes while also routing all their network traffic through a MITM proxy. The combination of arbitrary command execution and covert network interception represents a critical risk: an AI agent could spawn malicious processes, exfiltrate data, intercept credentials, or manipulate network traffic.
From the tool's definition "Spawn a command with proxy env vars pre-configured" and "Traffic automatically routes through the MITM proxy"
Documented attack patterns abuse exactly the kind of access interceptor_spawn gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and Proxy, and nothing reaches the server without passing your rules. This is the rule we recommend for interceptor_spawn:
{
"version": "1",
"default": "deny",
"tools": {
"interceptor_spawn": {
"limits": [
{
"counter": "interceptor_spawn_rate",
"window": "minute",
"max": 10,
"scope": "grant"
}
]
}
}
}interceptor_spawn stays usable, but rate-capped — a runaway agent can't fire it dozens of times a minute. Everything else on the server is denied unless you say otherwise.
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Spawn a command with proxy env vars pre-configured (HTTP_PROXY, HTTPS_PROXY, SSL_CERT_FILE, NODE_EXTRA_CA_CERTS, CURL_CA_BUNDLE, and 15+ more). Traffic automatically routes through the MITM proxy. It is categorised as a Execute tool in the Proxy MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.
Register the Proxy MCP server in PolicyLayer and add a rule for interceptor_spawn: 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 Proxy. Nothing to install.
interceptor_spawn 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 interceptor_spawn 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 interceptor_spawn. 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.
interceptor_spawn is provided by the Proxy MCP server (yfe404/proxy-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Start from Proxy, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.
Free to start. No card required.
89 Proxy tools catalogued and risk-classified — across an index of 43,000+ MCP servers.