Skip to content

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

High severity GitHub Reviewed Published Oct 26, 2023 in browserify/browserify-sign • Updated Mar 7, 2024

Package

npm browserify-sign (npm)

Affected versions

>= 2.6.0, <= 4.2.1

Patched versions

4.2.2

Description

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

References

@ljharb ljharb published to browserify/browserify-sign Oct 26, 2023
Published by the National Vulnerability Database Oct 26, 2023
Published to the GitHub Advisory Database Oct 26, 2023
Reviewed Oct 26, 2023
Last updated Mar 7, 2024

Severity

High

CVSS overall score

This score calculates overall vulnerability severity from 0 to 10 and is based on the Common Vulnerability Scoring System (CVSS).
/ 10

CVSS v3 base metrics

Attack vector
Network
Attack complexity
Low
Privileges required
None
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
High
Availability
None

CVSS v3 base metrics

Attack vector: More severe the more the remote (logically and physically) an attacker can be in order to exploit the vulnerability.
Attack complexity: More severe for the least complex attacks.
Privileges required: More severe if no privileges are required.
User interaction: More severe when no user interaction is required.
Scope: More severe when a scope change occurs, e.g. one vulnerable component impacts resources in components beyond its security scope.
Confidentiality: More severe when loss of data confidentiality is highest, measuring the level of data access available to an unauthorized user.
Integrity: More severe when loss of data integrity is the highest, measuring the consequence of data modification possible by an unauthorized user.
Availability: More severe when the loss of impacted component availability is highest.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N

EPSS score

0.077%
(35th percentile)

Weaknesses

CVE ID

CVE-2023-46234

GHSA ID

GHSA-x9w5-v3q2-3rhw

Source code

Credits

Loading Checking history
See something to contribute? Suggest improvements for this vulnerability.