Vulnerability DatabaseCVE-2024-21500

CVE-2024-21500:
vulnerability analysis and mitigation

Overview

CVE-2024-21500 affects all versions of the github.com/greenpau/caddy-security package, which is a security plugin for the Caddy web server. The vulnerability was discovered in September 2023 and publicly disclosed on February 16, 2024. The issue relates to improper restriction of excessive authentication attempts in the two-factor authentication (2FA) implementation (Snyk, Trail of Bits).

Technical details

The vulnerability stems from insufficient protection against brute-force attacks in the two-factor authentication system. While the application implements a blocking mechanism after several failed 2FA code attempts, attackers can circumvent this protection by automating the full multistep 2FA process. The vulnerability has been assigned a CVSS v3.1 base score of 4.8 (Medium) with the vector string CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N, indicating that it is network-accessible but requires high attack complexity (Snyk).

Impact

Successful exploitation of this vulnerability could allow attackers to bypass the two-factor authentication mechanism through automated brute-force attacks. This could potentially lead to unauthorized access to protected resources and compromise of user accounts that rely on 2FA for additional security (Trail of Bits).

Mitigation and workarounds

To address this vulnerability, it is recommended to enforce a minimum six-digit code length in the MFA configuration and implement an account locking mechanism that triggers after a specified number of invalid 2FA code attempts. Additionally, reauthentication should be required for critical actions involving sensitive account information or security settings, with an exception possible for users who have logged in within the last 10 minutes (GitHub Issue).

Community reactions

The vulnerability was initially reported to the caddy-security plugin maintainers on August 7, 2023. On August 23, 2023, the maintainers confirmed that there were no near-term plans to address the reported vulnerabilities. The issue was publicly disclosed on September 18, 2023, when Trail of Bits published their findings along with other security flaws discovered in the plugin (Trail of Bits).