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HIGH AI PREVALENCE: HIGH auth.flow.weak-password-hash

A password is being hashed with a fast, general-purpose hash (MD5/SHA-1/SHA-256/SHA-512 via crypto.createHash).

Why AI tools produce this: AI coding tools generate this anti-pattern by default, it appears in a large share of AI-written auth code.

Why this matters

These functions are designed to be FAST, so an attacker who steals the database can brute-force billions of candidate passwords per second on commodity GPUs. Salting alone does not fix this.

Use a dedicated, deliberately-slow password hashing function instead: bcrypt, argon2 (argon2id), or scrypt (crypto.scrypt). These add a tunable work factor that makes large-scale brute-forcing infeasible.

VULNERABLE
vulnerable.ts
import crypto, { createHash } from 'node:crypto';

declare const password: string;
declare const userPassword: string;
declare const newPasswd: string;
declare const oldPwd: string;

// ruleid: auth.flow.weak-password-hash -- MD5 chained
export const h1 = crypto.createHash('md5').update(password).digest('hex');

// ruleid: auth.flow.weak-password-hash -- SHA-1 chained
export const h2 = crypto.createHash('sha1').update(userPassword).digest('hex');

// ruleid: auth.flow.weak-password-hash -- SHA-256 chained, destructured import
export const h3 = createHash('sha256').update(newPasswd).digest('base64');

// ruleid: auth.flow.weak-password-hash -- SHA-512 chained with encoding arg
export const h4 = crypto.createHash('sha512').update(oldPwd, 'utf8').digest('hex');

// ruleid: auth.flow.weak-password-hash -- two-step form
const hasher = crypto.createHash('sha256');
hasher.update(password);
export const h5 = hasher.digest('hex');

export function hashPassword(pwd: string): string {
  // ruleid: auth.flow.weak-password-hash -- param named like a password
  return crypto.createHash('sha256').update(pwd).digest('hex');
}
SAFE
safe.ts
import crypto, { createHash, createHmac } from 'node:crypto';
import bcrypt from 'bcrypt';
import argon2 from 'argon2';

declare const password: string;
declare const fileBuffer: Buffer;
declare const payload: string;
declare const hmacKey: string;

// ok: auth.flow.weak-password-hash -- bcrypt is a real password hash
export const b = await bcrypt.hash(password, 12);

// ok: auth.flow.weak-password-hash -- argon2id is a real password hash
export const a = await argon2.hash(password);

// ok: auth.flow.weak-password-hash -- scrypt is a real password hash
crypto.scrypt(password, 'salt', 64, (_err, derivedKey) => {
  void derivedKey;
});

// ok: auth.flow.weak-password-hash -- checksum of a file buffer, not a password
export const checksum = crypto.createHash('sha256').update(fileBuffer).digest('hex');

// ok: auth.flow.weak-password-hash -- generic content digest, not a password
export const etag = createHash('sha1').update(payload).digest('hex');

// ok: auth.flow.weak-password-hash -- HMAC signature, not password hashing
export const sig = createHmac('sha256', hmacKey).update(payload).digest('hex');

// ok: auth.flow.weak-password-hash -- two-step digest over a file buffer
const fileHasher = crypto.createHash('sha512');
fileHasher.update(fileBuffer);
export const fileDigest = fileHasher.digest('hex');

Suppressing this rule

If a finding is a genuine false positive, scope the suppression to the exact line and leave a reason, never disable the rule project-wide. Disable directives are line-scoped by design.

// oauthlint-disable-next-line auth.flow.weak-password-hash -- <reason>

References

https://cheatsheetseries.owasp.org/cheatsheets/Password_Storage_Cheat_Sheet.html ↗https://cwe.mitre.org/data/definitions/916.html ↗