owlwarden

Fix broken cryptographic primitive protecting a secret in Express

A hash, cipher, or random source that cannot carry the weight it has been given: MD5 or SHA-1 over a password, a DES or ECB cipher, or Math.random() producing a token. Each has a drop-in replacement in the standard library, so the fix is small - the cost of not making it is that the protection is decorative.

high likely Express CWE-327 / OWASP A02:2021

The vulnerable pattern in Express

HIGH likely Broken cryptographic primitive protecting a secret A02:2021 src/account.ts:11:35 9 │ // weak-crypto: MD5 over a password. Fast by design, which is the attacker's 10 │ // advantage - a GPU tries billions of candidates a second. 11 │ const passwordHash = createHash('md5').update(req.body.password).digest('hex') │ ~~~~~ fast hash protecting a credential 12 │ 13 │ // weak-crypto: a session id anyone can predict from a few samples.

This finding comes from the Express fixture in the owlwarden test suite. This hash is fast, and speed is the attacker's advantage: a commodity GPU tries billions of candidates a second, so a leaked table of these hashes is a leaked table of the values behind them. Password hashing needs a deliberately slow algorithm with a per-value salt.

The corrected handler

Replace the hash at the point of use; there is no middleware for this.

import { randomBytes, randomUUID, scrypt } from 'node:crypto'

// Tokens and session ids: unpredictable, not merely random-looking.
const sessionId = randomUUID()
const resetToken = randomBytes(32).toString('base64url')

// Passwords: a slow hash with a per-password salt. bcrypt and argon2 are
// equally correct; scrypt needs no dependency.
const salt = randomBytes(16)
const hash = await new Promise<Buffer>((resolve, reject) =>
  scrypt(password, salt, 64, (error, key) => (error ? reject(error) : resolve(key))),
)

If you are not using Express

Use a slow, salted hash for passwords and a cryptographic random source for tokens. Both are in the Node standard library; neither needs a dependency.

Check your own repository

npx owlwarden scan
npx owlwarden explain weak-crypto

Runs on your machine. No account, no telemetry, no network unless you ask. In CI, SARIF uploads to code scanning and the exit code is the gate.

Other Express checks

Rules with a tested Express example.

weak-crypto for every framework / All rules / owlwarden