GoCD API authentication of user access tokens subject to timing attack during comparison

Vulnerability Description

GoCD is a continuous delivery server. GoCD helps you automate and streamline the build-test-release cycle for continuous delivery of your product. GoCD versions from 19.2.0 to 19.10.0 (inclusive) are subject to a timing attack in validation of access tokens due to use of regular string comparison for validation of the token rather than a constant time algorithm. This could allow a brute force attack on GoCD server API calls to observe timing differences in validations in order to guess an access token generated by a user for API access. This issue is fixed in GoCD version 19.11.0. As a workaround, users can apply rate limiting or insert random delays to API calls made to GoCD Server via a reverse proxy or other fronting web server. Another workaround, users may disallow use of access tokens by users by having an administrator revoke all access tokens through the "Access Token Management" admin function.

References

• https://github.com/gocd/gocd/security/advisories/GHSA-999p-fp84-jcpq
• https://github.com/gocd/gocd/commit/236d4baf92e6607f2841c151c855adcc477238b8
• https://github.com/gocd/gocd/releases/tag/19.11.0
• https://www.gocd.org/releases/#19-11-0