Version Details and Security Vulnerabilities

Summary

This affects both:

1. Unsupported algos (e.g. sha3-256 / sha3-512 / sha512-256)
2. Supported but non-normalized algos (e.g. Sha256 / Sha512 / SHA1 / sha-1 / sha-256 / sha-512)

All of those work correctly in Node.js, but this polyfill silently returns highly predictable ouput

Under Node.js (only with pbkdf2/browser import, unlikely) / Bun (pbkdf2 top-level import is affected), the memory is not zero-filled but is uninitialized, as Buffer.allocUnsafe is used

Under browsers, it just returns zero-filled buffers (Which is also critical, those are completely unacceptable as kdf output and ruin security)

Were you affected?

The full list of arguments that were not affected were literal:

• 'md5'
• 'sha1'
• 'sha224'
• 'sha256'
• 'sha384'
• 'sha512'
• 'rmd160'
• 'ripemd160'

Any other arguments, e.g. representation variations of the above ones like 'SHA-1'/'sha-256'/'SHA512' or different algos like 'sha3-512'/'blake2b512', while supported on Node.js crypto module, returned predictable output on pbkdf2 (or crypto browser/bundlers polyfill)

Beware of packages re-exporting this under a different signature, like (abstract):

const crypto = require('crypto')
module.exports.deriveKey = (algo, pass, salt) => crypto.pbkdf2Sync(pass, salt, 2048, 64, algo)

In this case, the resulting deriveKey method is also affected (to the same extent / conditions as listed here).

Environments

This affects require('crypto') in polyfilled mode (e.g. from crypto-browserify, node-libs-browser, vite-plugin-node-polyfills, node-stdlib-browser, etc. -- basically everything that bundles/polfyills crypto

• In bundled code (e.g. Webpack / Vite / whatever), this affects require('crypto') and require('pbkdf2')
• On Node.js, this does not affect require('pbkdf2') (or require('crypto') obviously), but affects require('pbkdf2/browser')
• On Bun, this does affect require('pbkdf2') and require('pbkdf2/browser') (and returns uninitialized memory, often zeros / sparse flipped bytes)

PoC

const node = require('crypto')
const polyfill = require('pbkdf2/browser')

const algos = [
  'sha3-512', 'sha3-256', 'SHA3-384',
  'Sha256', 'Sha512', 'sha512-256',
  'SHA1', 'sha-1',
  'blake2b512',
  'RMD160', 'RIPEMD-160', 'ripemd-160',
]
for (const algo of algos) {
  for (const { pbkdf2Sync } of [node, polyfill]) {
    const key = pbkdf2Sync('secret', 'salt', 100000, 64, algo)
    console.log(`${algo}: ${key.toString('hex')}`);
  }
}

Output (odd lines are Node.js, even is pbkdf2 module / polyfill):

sha3-512: de00370414a3251d6d620dc8f7c371644e5d7f365ab23b116298a23fa4077b39deab802dd61714847a5c7e9981704ffe009aee5bb40f6f0103fc60f3d4cedfb0
sha3-512: 00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000
sha3-256: 76bf06909b91e4c968700078ee36af92019d0839ab1fea2f345c6c8685074ca0179302633fbd84d22cff4f8744952b2d07edbfc9658e95d30fb4e93ee067c7c9
sha3-256: 00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000
SHA3-384: 2b2b41b73f9b7bcd023f709ea84ba3c29a88edc311b737856ba9e74a2d9a928f233eb8cb404a9ba93c276edf6380c692140024a0bc12b75bfa38626207915e01
SHA3-384: 00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000
Sha256: 3fa094211c0cf2ed1d332ab43adc69aab469f0e0f2cae6345c81bb874eef3f9eb2c629052ec272ca49c2ee95b33e7ba6377b2317cd0dacce92c4748d3c7a45f0
Sha256: 00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000
Sha512: 3745e482c6e0ade35da10139e797157f4a5da669dad7d5da88ef87e47471cc47ed941c7ad618e827304f083f8707f12b7cfdd5f489b782f10cc269e3c08d59ae
Sha512: 00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000
sha512-256: e423f61987413121418715d0ebf64cb646042ae9a09fe4fd2c764a4f186ba28cf70823fdc2b03dda67a0d977c6f0a0612e5ed74a11e6f32b033cb658fa9f270d
sha512-256: 00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000
SHA1: 0e24bc5a548b236e3eb3b22317ef805664a88747c725cd35bfb0db0e4ae5539e3ed5cd5ba8c0ac018deb6518059788c8fffbe624f614fbbe62ba6a6e174e4a72
SHA1: 00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000
sha-1: 0e24bc5a548b236e3eb3b22317ef805664a88747c725cd35bfb0db0e4ae5539e3ed5cd5ba8c0ac018deb6518059788c8fffbe624f614fbbe62ba6a6e174e4a72
sha-1: 00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000
blake2b512: d3d661100c5ffb79bdf3b5c77d1698e621414cba40e2348bd3f1b10fbd2fe97bff4dc7d76474955bfefa61179f2a37e9dddedced0e7e79ef9d8c678080d45926
blake2b512: 00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000
RMD160: ec65dbad1485616cf0426725d64e009ad3e1633543746ccb56b7f06eb7ce51d0249aaef27c879f32911a7c0accdc83389c2948ddec439114f6165366f9b4cca2
RMD160: 00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000
RIPEMD-160: ec65dbad1485616cf0426725d64e009ad3e1633543746ccb56b7f06eb7ce51d0249aaef27c879f32911a7c0accdc83389c2948ddec439114f6165366f9b4cca2
RIPEMD-160: 00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000
ripemd-160: ec65dbad1485616cf0426725d64e009ad3e1633543746ccb56b7f06eb7ce51d0249aaef27c879f32911a7c0accdc83389c2948ddec439114f6165366f9b4cca2
ripemd-160: 00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000

Uninitialized memory

const { pbkdf2Sync } = require('pbkdf2/browser') // or just 'pbkdf2' on Bun will do this too

let prev
for (let i = 0; i < 100000; i++) {
  const key = pbkdf2Sync('secret', 'salt', 100000, 64, 'sha3-256')
  const hex = key.toString('hex')
  if (hex !== prev) console.log(hex);
  prev = hex
}

Affected versions

Seems to be since https://github.com/browserify/pbkdf2/commit/9699045c37a07f8319cfb8d44e2ff4252d7a7078

Impact

This is critical, browserifying code might silently generate zero-filled keys instead of proper ones, for code that was working on Node.js or in test environment

Just updating to a fixed version is not enough: if anyone was using pbkdf2 lib (e.g. via crypto-browserify or directly) on algos not from the literal string list (see "were you affected"), recheck where those keys went / how they were used, and take action accordingly

Note

Most likely, you receive this either through a subdep using pbkdf2 module directly (and then it is used), or through crypto-browserify (and the usage depends on whether you or any of your subdeps were calling pbkdf2/pbkdf2Sync methods from Node.js crypto inside your bundle)

When targeting non-Node.js, prever avoiding Node.js crypto polyfill at all, and use crypto.subtle and/or modern/audited cryptography primitives instead

Summary

On historic but declared as supported Node.js versions (0.12-2.x), pbkdf2 silently disregards Uint8Array input

This only affects Node.js <3.0.0, but pbkdf2 claims to:

• Support Node.js >= 0.12 (and there seems to be ongoing effort in this repo to maintain that)
• Support Uint8Array input (input is typechecked against Uint8Array, and the error message includes e.g. "Password must be a string, a Buffer, a typed array or a DataView"

Details

The error is in toBuffer method

This vulnerability somehow even made it to tests: https://github.com/browserify/pbkdf2/commit/eb9f97a66ed83836bebc4ff563a1588248708501 There, resultsOld (where mismatch results) are just invalid output generated from empty password/salt instead of the supplied one

PoC

On Node.js/io.js < 3.0.0

> require('pbkdf2').pbkdf2Sync(new Uint8Array([1,2,3]), new Uint8Array([1,3,4]), 1024, 32, 'sha256')
<Buffer 21 53 cd 5b a5 f0 15 39 2f 68 e2 40 8b 21 ba ca 0e dc 7b 20 d5 45 a4 8a ea b5 95 9f f0 be bf 66>

// But that's just a hash of empty data with empty password:
> require('pbkdf2').pbkdf2Sync('', '', 1024, 32, 'sha256')
<Buffer 21 53 cd 5b a5 f0 15 39 2f 68 e2 40 8b 21 ba ca 0e dc 7b 20 d5 45 a4 8a ea b5 95 9f f0 be bf 66>

// Node.js crypto is fine even on that version:
> require('crypto').pbkdf2Sync(new Uint8Array([1,2,3]), new Uint8Array([1,3,4]), 1024, 32, 'sha256')
<Buffer 78 10 cc 84 b7 bb 85 cd c8 37 ca 68 da a9 4c 33 db ae c2 3d 5b d4 95 76 da 33 f9 95 ac 51 f4 45>

// Empty hash from Node.js, for comparison
> require('crypto').pbkdf2Sync('', '', 1024, 32, 'sha256')
<Buffer 21 53 cd 5b a5 f0 15 39 2f 68 e2 40 8b 21 ba ca 0e dc 7b 20 d5 45 a4 8a ea b5 95 9f f0 be bf 66>

Impact

Static hashes being outputted and used as keys/passwords can completely undermine security That said, no one should be using those Node.js versions anywhere now, so I would recommend to just drop them This lib should not pretend to work on those versions while outputting static data though

Just updating to a fixed version is not enough: if anyone was using pbkdf2 lib (do not confuse with Node.js crypto.pbkdf2) or anything depending on it with Node.js/io.js < 3.0.0, recheck where those keys went / how they were used, and take action accordingly