Description

WWBN AVideo has a SSRF via same-domain hostname with alternate port bypasses isSSRFSafeURL

Summary

The isSSRFSafeURL() function in objects/functions.php contains a same-domain shortcircuit (lines 4290-4296) that allows any URL whose hostname matches webSiteRootURL to bypass all SSRF protections. Because the check compares only the hostname and ignores the port, an attacker can reach arbitrary ports on the AVideo server by using the site's public hostname with a non-standard port. The response body is saved to a web-accessible path, enabling full exfiltration.

Details

Commit 40872e529 fixed an extension-based SSRF bypass by making isSSRFSafeURL() unconditional. However, isSSRFSafeURL() itself contains a same-domain shortcircuit that returns true when the URL's hostname matches webSiteRootURL's hostname, without validating the port:

// objects/functions.php:4290-4296
if (!empty($global['webSiteRootURL'])) {
    $siteHost = strtolower(parse_url($global['webSiteRootURL'], PHP_URL_HOST));
    if ($host === $siteHost) {
        _error_log("isSSRFSafeURL: allowing same-domain request to {$host} (matches webSiteRootURL)");
        return true;  // Returns immediately — port, path, scheme all unchecked
    }
}...
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The attack flow through objects/aVideoEncoder.json.php:

User-supplied $_REQUEST['downloadURL'] is passed to downloadVideoFromDownloadURL() at line 166

isSSRFSafeURL() is called at line 368 — passes due to hostname match

url_get_contents($downloadURL) fetches the attacker-controlled URL at line 378

Response is written to Video::getStoragePath() . "cache/tmpFile/" . basename($downloadURL) at line 393-395

The cache/tmpFile/ directory is under the web-accessible videos storage path. The attacker can retrieve the file to exfiltrate the internal service response.

The auth requirement is User::canUpload() (line 59), which is satisfied by any authenticated user with upload permission. Alternatively, a valid video_id_hash (a per-video token) can be used via useVideoHashOrLogin() at line 57.

PoC

Assuming the AVideo instance is at https://avideo.example.com/ and an internal service runs on port 9998:

# Step 1: Authenticate and get cookies (any user with upload permission)
curl -c cookies.txt -X POST 'https://avideo.example.com/objects/login.json.php' \
  -d 'user=testuser&pass=testpass'

# The hostname matches webSiteRootURL so isSSRFSafeURL() returns true
curl -b cookies.txt -X POST 'https://avideo.example.com/objects/aVideoEncoder.json.php' \
  -d 'format=mp4&downloadURL=http://avideo.example.com:9998/large-internal-endpoint.mp4&videos_id=1&first_request=1'
...
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Note: The internal service response must be >= 20KB (or >= 5KB if the URL ends in .mp3) to pass the size check at line 384. For smaller responses, the attacker can target endpoints that return verbose output or append padding parameters.

The fix at 40872e529 specifically mentions blocking http://127.0.0.1:9998/probe.mp4. This bypass reaches the exact same internal service by replacing 127.0.0.1 with the site's public hostname — the DNS resolution points to the same server.

Impact

Internal service access: An authenticated attacker can reach any TCP port on the AVideo server that speaks HTTP, including databases with HTTP interfaces, monitoring endpoints, admin panels, cloud metadata services (if the hostname resolves to a cloud instance), and other co-hosted services.

Data exfiltration: Response bodies are written to a web-accessible directory, allowing the attacker to retrieve internal service responses.

Scope change: The vulnerability crosses from the AVideo application into other services on the same host, justifying S:C in CVSS scoring.

Bypass of existing fix: This directly circumvents the SSRF protection added in commit 40872e529.

Recommended Fix

The same-domain shortcircuit should validate that both the hostname and port match webSiteRootURL. Replace objects/functions.php lines 4290-4296:

// Allow same-domain requests ONLY if hostname AND port match webSiteRootURL
if (!empty($global['webSiteRootURL'])) {
    $siteHost = strtolower(parse_url($global['webSiteRootURL'], PHP_URL_HOST));
    $sitePort = parse_url($global['webSiteRootURL'], PHP_URL_PORT);
    $siteScheme = strtolower(parse_url($global['webSiteRootURL'], PHP_URL_SCHEME));
    // Default port based on scheme if not explicitly set
    if (empty($sitePort)) {
        $sitePort = ($siteScheme === 'https') ? 443 : 80;...
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This ensures the shortcircuit only fires for requests to the exact same origin (scheme-implied port or explicit port) as the configured site URL.

Mitigation

Aliases

References