AVideo vulnerable to IP Address Spoofing via Untrusted HTTP Headers in getRealIpAddr()

Summary

The getRealIpAddr() function in objects/functions.php trusts user-controlled HTTP headers to determine the client's IP address. An attacker can spoof their IP address by sending forged headers, bypassing any IP-based access controls or audit logging.

Vulnerable Code

File: objects/functions.php

$headers = [
    'HTTP_X_REAL_IP',      
    'HTTP_CLIENT_IP',    
    'HTTP_X_FORWARDED_FOR',
    'REMOTE_ADDR'
];

foreach ($headers as $header) {
    if (!empty($_SERVER[$header])) {
        $ips = explode(',', $_SERVER[$header]);
        foreach ($ips as $ipCandidate) {
            $ipCandidate = trim($ipCandidate);
            if (filter_var($ipCandidate, FILTER_VALIDATE_IP, 
                           FILTER_FLAG_IPV4)) {
                return $ipCandidate; 
            }
        }
    }
}

Attack Scenario

1. Attacker sends request with forged header:

X-Client-IP: 127.0.0.1

or

X-Real-IP: 192.168.1.1

2. getRealIpAddr() returns the forged IP
3. Any IP-based rate limiting, access control, or audit log that relies on this function is bypassed

Proof of Concept

curl -H "X-Client-IP: 127.0.0.1" \
     https://target.com/any_endpoint.php

The server now believes the request came from localhost.

Impact

• Bypass IP-based rate limiting
• Bypass IP-based access controls
• Forge audit log entries
• Potential privilege escalation if localhost is trusted