CVE-2023-46233

crypto-js is a JavaScript library of crypto standards. Prior to version 4.2.0, crypto-js PBKDF2 is 1,000 times weaker than originally specified in 1993, and at least 1,300,000 times weaker than current industry standard. This is because it both defaults to SHA1, a cryptographic hash algorithm considered insecure since at least 2005, and defaults to one single iteration, a 'strength' or 'difficulty' value specified at 1,000 when specified in 1993. PBKDF2 relies on iteration count as a countermeasure to preimage and collision attacks. If used to protect passwords, the impact is high. If used to generate signatures, the impact is high. Version 4.2.0 contains a patch for this issue. As a workaround, configure crypto-js to use SHA256 with at least 250,000 iterations.

crypto-js is a JavaScript library of crypto standards. Prior to version 4.2.0, crypto-js PBKDF2 is 1,000 times weaker than originally specified in 1993, and at least 1,300,000 times weaker than current industry standard. This is because it both defaults to SHA1, a cryptographic hash algorithm considered insecure since at least 2005, and defaults to one single iteration, a 'strength' or 'difficulty' value specified at 1,000 when specified in 1993. PBKDF2 relies on iteration count as a countermeasure to preimage and collision attacks. If used to protect passwords, the impact is high. If used to generate signatures, the impact is high. Version 4.2.0 contains a patch for this issue. As a workaround, configure crypto-js to use SHA256 with at least 250,000 iterations.

Impact

Summary

Crypto-js PBKDF2 is 1,000 times weaker than originally specified in 1993, and at least 1,300,000 times weaker than current industry standard. This is because it both (1) defaults to SHA1, a cryptographic hash algorithm considered insecure since at least 2005 and (2) defaults to one single iteration, a 'strength' or 'difficulty' value specified at 1,000 when specified in 1993. PBKDF2 relies on iteration count as a countermeasure to preimage and collision attacks.

Potential Impact:

1. If used to protect passwords, the impact is high.
2. If used to generate signatures, the impact is high.

Probability / risk analysis / attack enumeration:

1. For at most $45,000, an attacker, given control of only the beginning of a crypto-js PBKDF2 input, can create a value which has identical cryptographic signature to any chosen known value.
2. Due to the length extension attack on SHA1, we can create a value that has identical signature to any unknown value, provided it is prefixed by a known value. It does not matter if PBKDF2 applies 'salt' or 'pepper' or any other secret unknown to the attacker. It will still create an identical signature.

Update: PBKDF2 requires a pseudo-random function that takes two inputs, so HMAC-SHA1 is used rather than plain SHA1. HMAC is not affected by length extension attacks. However, by defaulting to a single PBKDF2 iteration, the hashes do not benefit from the extra computational complexity that PBKDF2 is supposed to provide. The resulting hashes therefore have little protection against an offline brute-force attack.

crypto-js has 10,642 public users as displayed on NPM, today October 11th 2023. The number of transient dependents is likely several orders of magnitude higher.

A very rough GitHub search shows 432 files cross GitHub using PBKDF2 in crypto-js in Typescript or JavaScript, but not specifying any number of iterations.

Affected versions

All versions are impacted. This code has been the same since crypto-js was first created.

Further Cryptanalysis

The issue here is especially egregious because the length extension attack makes useless any secret that might be…

crypto-js is a JavaScript library of crypto standards. Prior to version 4.2.0, crypto-js PBKDF2 is 1,000 times weaker than originally specified in 1993, and at least 1,300,000 times weaker than current industry standard. This is because it both defaults to SHA1, a cryptographic hash algorithm considered insecure since at least 2005, and defaults to one single iteration, a 'strength' or 'difficulty' value specified at 1,000 when specified in 1993. PBKDF2 relies on iteration count as a countermeasure to preimage and collision attacks. If used to protect passwords, the impact is high. If used to generate signatures, the impact is high. Version 4.2.0 contains a patch for this issue. As a workaround, configure crypto-js to use SHA256 with at least 250,000 iterations.

crypto-js is a JavaScript library of crypto standards. Prior to version 4.2.0, crypto-js PBKDF2 is 1,000 times weaker than originally specified in 1993, and at least 1,300,000 times weaker than current industry standard. This is because it both defaults to SHA1, a cryptographic hash algorithm considered insecure since at least 2005, and defaults to one single iteration, a 'strength' or 'difficulty' value specified at 1,000 when specified in 1993. PBKDF2 relies on iteration count as a countermeasure to preimage and collision attacks. If used to protect passwords, the impact is high. If used to generate signatures, the impact is high. Version 4.2.0 contains a patch for this issue. As a workaround, configure crypto-js to use SHA256 with at least 250,000 iterations.

crypto-js is a JavaScript library of crypto standards. Prior to version 4.2.0, crypto-js PBKDF2 is 1,000 times weaker than originally specified in 1993, and at least 1,300,000 times weaker than current industry standard. This is because it both defaults to SHA1, a cryptographic hash algorithm considered insecure since at least 2005, and defaults to one single iteration, a 'strength' or 'difficulty' value specified at 1,000 when specified in 1993. PBKDF2 relies on iteration count as a countermeasure to preimage and collision attacks. If used to protect passwords, the impact is high. If used to generate signatures, the impact is high. Version 4.2.0 contains a patch for this issue. As a workaround, configure crypto-js to use SHA256 with at least 250,000 iterations.