RandomAlphaNumeric and CryptoRandomAlphaNumeric are not as random as they should be
### Impact A security-sensitive bug was discovered by Open Source Developer *Erik Sundell of Sundell Open Source Consulting AB*. The functions `RandomAlphaNumeric(int)` and `CryptoRandomAlphaNumeric(int)` are not as random as they should be. Small values of `int` in the functions above will return a smaller subset of results than they should. For example, `RandomAlphaNumeric(1)` will always return a digit in the 0-9 range, while `RandomAlphaNumeric(4)` will return around ~7 million of the ~13M possible permutations. This is considered a security release because programs that rely upon random generators for passwords are at an increased risk of brute force-style password guessing. There is also a higher probability of collision. The problem was the result of a mistaken regular expression that only accepted random strings if they contained a digit from `[0-9]`. That restriction has been removed. ### Patches This issue has been corrected in v1.1.1. ### Workarounds If you cannot upgrade to v1.1.1, you can work around the issue by calling `RandomAlphaNumericCustom(N, true, true)`|`CryptoRandomAlphaNumericCustom(N, true, true)` instead. (Where `N` is the desired length, and `true` is the literal boolean `true`.)
describes (1)
Related CVEs.
| ID | severity | exploitable | ||
|---|---|---|---|---|
| CVE-2021-4238US | critical9.1 | — | ||
Randomly-generated alphanumeric strings contain significantly less entropy than expected. The RandomAlphaNumeric and CryptoRandomAlphaNumeric functions always return strings contai… | ||||
references
External citations — patches, advisories, analysis.
- https://github.com/Masterminds/goutilsPACKAGE
- https://github.com/Masterminds/goutils/commit/869801f20f9f1e7ecdbdb6422049d8241270d5e1WEB
- https://github.com/Masterminds/goutils/commit/f1923532a168b8203bfe956d8cd3b17ebece5982WEB
- https://github.com/Masterminds/goutils/releases/tag/v1.1.1WEB
- https://github.com/Masterminds/goutils/security/advisories/GHSA-xg2h-wx96-xgxrWEB
- https://nvd.nist.gov/vuln/detail/CVE-2021-4238ADVISORY
- https://pkg.go.dev/vuln/GO-2022-0411WEB
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