Flowise: SSRF Protection Bypass (TOCTOU & Default Insecure)

// PoC for httpSecurity.ts Bypasses
import * as dns from 'dns/promises';

// Mocking the checkDenyList logic from Flowise
async function checkDenyList(url: string) {
    const deniedIPs = ['127.0.0.1', '0.0.0.0']; // Simplified deny list logic

    if (!process.env.HTTP_DENY_LIST) {
        console.log(\"⚠️  HTTP_DENY_LIST not set. Returning allowed.\");
        return; // Vulnerability 1: Default Insecure
    }

    const { hostname } = new URL(url);
    const { address } = await dns.lookup(hostname);

    if (deniedIPs.includes(address)) {
        throw new Error(`IP ${address} is denied`);
    }
    console.log(`✅ IP ${address} allowed check.`);
}

async function runPoC() {
    console.log(\"--- Test 1: Default Configuration (Unset HTTP_DENY_LIST) ---\");
    // Ensure env var is unset
    delete process.env.HTTP_DENY_LIST;
    try {
        await checkDenyList('http://127.0.0.1');
        console.log(\"[PASS] Default config allowed localhost access.\");
    } catch (e) {
        console.log(\"[FAIL] Blocked:\", e.message);
    }

    console.log(\"\
--- Test 2: 'private' Keyword Bypass (Logic Flaw) ---\");
    process.env.HTTP_DENY_LIST = 'private'; // User expects this to block localhost
    try {
        await checkDenyList('http://127.0.0.1');
        // In real Flowise code, 'private' is not expanded to IPs, so it only blocks the string \"private\"
        console.log(\"[PASS] 'private' keyword failed to block localhost (Mock simulation).\");
    } catch (e) {
        console.log(\"[FAIL] Blocked:\", e.message);
    }
}

runPoC();