Описание
Insecure random number generation in keypair
Description and Impact
A bug in the pseudo-random number generator used by keypair versions up to and including 1.0.3 could allow for weak RSA key generation. This could enable an attacker to decrypt confidential messages or gain authorized access to an account belonging to the victim. We recommend replacing any RSA keys that were generated using keypair version 1.0.3 or earlier.
Fix
- The bug in the pseudo-random number generator is fixed in commit
9596418. - If the crypto module is available, it is used instead of the pseudo-random number generator. Also fixed in
9596418
Additional Details
The specific line with the flaw is:
The definition of putByte is
Simplified, this is String.fromCharCode(String.fromCharCode(next & 0xFF)). This results in most of the buffer containing zeros. An example generated buffer:
(Note: truncated for brevity)
Since it is masking with 0xFF, approximately 97% of the bytes are converted to zeros. The impact is that each byte in the RNG seed has a 97% chance of being 0 due to incorrect conversion.
Credit
This issue was reported to GitHub Security Lab by Ross Wheeler of Axosoft. It was discovered by Axosoft engineer Dan Suceava, who noticed that keypair was regularly generating duplicate RSA keys. GitHub security engineer @vcsjones (Kevin Jones) independently investigated the problem and identified the cause and source code location of the bug.
Ссылки
- https://github.com/juliangruber/keypair/security/advisories/GHSA-3f99-hvg4-qjwj
- https://nvd.nist.gov/vuln/detail/CVE-2021-41117
- https://github.com/juliangruber/keypair/commit/9596418d3363d3e757676c0b6a8f2d35a9d1cb18
- https://github.com/juliangruber/keypair/releases/tag/v1.0.4
- https://securitylab.github.com/advisories/GHSL-2021-1012-keypair
Пакеты
keypair
< 1.0.4
1.0.4
Связанные уязвимости
keypair is a a RSA PEM key generator written in javascript. keypair implements a lot of cryptographic primitives on its own or by borrowing from other libraries where possible, including node-forge. An issue was discovered where this library was generating identical RSA keys used in SSH. This would mean that the library is generating identical P, Q (and thus N) values which, in practical terms, is impossible with RSA-2048 keys. Generating identical values, repeatedly, usually indicates an issue with poor random number generation, or, poor handling of CSPRNG output. Issue 1: Poor random number generation (`GHSL-2021-1012`). The library does not rely entirely on a platform provided CSPRNG, rather, it uses it's own counter-based CMAC approach. Where things go wrong is seeding the CMAC implementation with "true" random data in the function `defaultSeedFile`. In order to seed the AES-CMAC generator, the library will take two different approaches depending on the JavaScript execution environ