phanalist

E0056: Weak Randomness for Security-Sensitive Value

In plain English: Functions such as rand(), mt_rand(), and uniqid() are predictable. They are fine for games and samples, but not for tokens, passwords, salts, nonces, or other secrets.

Why it matters: If an attacker can predict a token, they may be able to guess password-reset links, CSRF tokens, session identifiers, or API keys.

Bad

$token = uniqid();
$password = password_hash(mt_rand(), PASSWORD_DEFAULT);
$nonce = (string) rand();

Good

$token = bin2hex(random_bytes(32));
$code = random_int(100000, 999999);
$passwordHash = password_hash($password, PASSWORD_DEFAULT);

random_bytes() is for tokens and salts. random_int() is for numeric codes. password_hash() handles password salts for you.

What the rule checks

• Weak generators: rand(), mt_rand(), uniqid(), lcg_value(), str_shuffle(), and array_rand()
• Assignments to variables whose names look security-sensitive, such as token, secret, password, nonce, salt, csrf, or api_key
• Values passed to password_hash(), hash_hmac(), hash(), openssl_encrypt(), openssl_sign(), cookie functions, or session ID functions

When it does not report

• The random value is used for a non-security purpose, such as a sample or a game.
• The code uses random_bytes() or random_int().
• hash() or hash_hmac() uses a non-cryptographic checksum such as xxh128, crc32, fnv1a64, or murmur3.
• A custom security wrapper hides the sink from the rule.

How to fix

• Use random_bytes() for tokens, salts, and nonces.
• Use random_int() for numeric verification codes.
• Use password_hash() for passwords.
• Do not use uniqid() for anything security-sensitive.

Model limits

• Variable names are matched heuristically, not by type or data flow.
• Custom security wrappers and sinks are not recognized.

Configuration

E0056 has no configuration options and is enabled by default.

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