GHSA-x9w5-v3q2-3rhw

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GHSA-x9w5-v3q2-3rhw

Summary: browserify-sign upper bound check issue in `dsaVerify` leads to a signature forgery attack

Details: ### Summary An upper bound check issue in `dsaVerify` function allows an attacker to construct signatures that can be successfully verified by any public key, thus leading to a signature forgery attack. ### Details In `dsaVerify` function, it checks whether the value of the signature is legal by calling function `checkValue`, namely, whether `r` and `s` are both in the interval `[1, q - 1]`. However, the second line of the `checkValue` function wrongly checks the upper bound of the passed parameters, since the value of `b.cmp(q)` can only be `0`, `1` and `-1`, and it can never be greater than `q`. In this way, although the values of `s` cannot be `0`, an attacker can achieve the same effect as zero by setting its value to `q`, and then send `(r, s) = (1, q)` to pass the verification of any public key. ### Impact All places in this project that involve DSA verification of user-input signatures will be affected by this vulnerability. ### Fix PR: Since the temporary private fork was deleted, here's a webarchive of the PR discussion and diff pages: [PR webarchive.zip](https://github.com/browserify/browserify-sign/files/13172957/PR.webarchive.zip)

References: https://github.com/browserify/browserify-sign/security/advisories/GHSA-x9w5-v3q2-3rhw, https://nvd.nist.gov/vuln/detail/CVE-2023-46234, https://github.com/browserify/browserify-sign/commit/85994cd6348b50f2fd1b73c54e20881416f44a30, https://github.com/browserify/browserify-sign, https://lists.debian.org/debian-lts-announce/2023/10/msg00040.html, https://lists.fedoraproject.org/archives/list/[email protected]/message/3HUE6ZR5SL73KHL7XUPAOEL6SB7HUDT2, https://lists.fedoraproject.org/archives/list/[email protected]/message/6PVVPNSAGSDS63HQ74PJ7MZ3MU5IYNVZ, https://www.debian.org/security/2023/dsa-5539