Description

This detector identifies uses of short authentication tags in PHP cryptographic operations, specifically with OpenSSL and phpseclib libraries. Short authentication tags (typically less than 128 bits) in Galois/Counter Mode (GCM) encryption provide insufficient cryptographic security and can be vulnerable to forgery attacks.

Detection Strategy

• The detector checks if phpseclib cryptographic library is imported in the PHP code

• For each selected code node, it examines if the code contains OpenSSL encrypt operations with short authentication tags

• When phpseclib is imported, it also checks for calls to getTag() methods that return short authentication tags

• A vulnerability is reported when either short OpenSSL encryption tags or short phpseclib getTag calls are found in the code

Vulnerable code example

<?php
use phpseclib3\Crypt\AES;

function unsafeEncryption($data, $key) {
    $iv = random_bytes(12);
    $tag = '';
    
    // VULNERABLE: tag_length is 8 bytes, below the 12-byte security minimum...

✅ Secure code example

<?php
use phpseclib3\Crypt\AES;

function safeEncryption($data, $key) {
    $iv = random_bytes(12);
    $tag = '';
    
    // SAFE: Use default 16-byte tag length for strong authentication...