In Yubico pam-u2f before 1.3.1, local privilege escalation can sometimes occur. This product implements a Pluggable Authentication Module (PAM) that can be deployed to support authentication using a YubiKey or other FIDO compliant authenticators on macOS or Linux. This software package has an issue that allows for an authentication bypass in some configurations. An attacker would require the ability to access the system as an unprivileged user. Depending on the configuration, the attacker may also need to know the user's password.
The high CVSS score of 7.3 indicates that this vulnerability could have serious implications for organizations utilizing Yubico's pam-u2f authentication method. Risk to organizations includes potential unauthorized access, which can lead to further exploitation within the system.
Organizations should prioritize patching immediately, as this vulnerability presents a significant risk. Given its local attack vector with low complexity, an attacker could exploit it easily if they gain user access.
As of now, the vulnerability is listed as deferred, which indicates that while it has been acknowledged, it may not yet be actively being exploited or widely known. Nonetheless, organizations should not underestimate its potential impact.
Vulnerability Details
The vulnerability allows local privilege escalation, enabling attackers to bypass authentication under specific conditions. The CVSS score of 7.3 categorizes it as high severity due to the significant confidentiality, integrity, and availability impacts it could impose on affected systems.
Affected versions include all versions prior to 1.3.1. Organizations using Yubico pam-u2f should look for any configurations that could lead to authentication bypass.
Technical Analysis
The root cause of this vulnerability lies in the implementation of the Pluggable Authentication Module (PAM). Specifically, certain configurations may lead to problematic PAM_IGNORE return values in the pam_sm_authenticate function.
The attack vector is local, meaning an attacker must have physical or remote access to the system. The attack complexity is low, making this vulnerability particularly concerning. Privileges required are also low, as an attacker may exploit this vulnerability without needing high-level access.
User interaction is not required to exploit this vulnerability, which increases its risk profile. The high confidentiality, integrity, and availability impacts indicate that an attacker could potentially gain significant control over the affected systems.
Risk & Impact Analysis
Organizations utilizing Yubico pam-u2f should assess their exposure to this vulnerability. The potential for unauthorized access can lead to further internal attacks, making this a critical issue. The vulnerability's impact on confidentiality, integrity, and availability is significant, creating a broad blast radius.
Given its CVSS score of 7.3, organizations should address this vulnerability in priority patch cycles. While the vulnerability is currently marked as deferred, proactive remediation is essential to mitigate potential risks.
Exploitation Status
Signal | Status |
|---|---|
Known Exploit | No |
Public PoC | No |
Actively Exploited | No |
Ransomware Use | No |
Affected Versions
All versions prior to vendor patch (1.3.1) are affected by this vulnerability. Organizations using outdated versions should upgrade immediately to mitigate risks.
Mitigation & Remediation
To remediate this vulnerability, organizations should apply the latest patches provided by Yubico. The recommended version to upgrade to is 1.3.1 or higher. If patching is not immediately possible, organizations should consider network controls to limit unauthorized access and configuration hardening to minimize exposure.
Further, organizations should validate remediation through penetration testing to identify potential weaknesses in the authentication system.
Detection Guidance
Organizations should monitor logs for unusual authentication attempts and review configuration settings for the pam-u2f module. Look for behavioral anomalies that could indicate attempts to exploit this vulnerability and establish network signatures that flag unauthorized access attempts.
AppSecure Threat Intelligence Insight
The long-term significance of CVE-2025-23013 lies in its representation of potential weaknesses in authentication mechanisms. This vulnerability highlights the importance of validating security controls within PAM modules and ensuring that configurations do not allow for authentication bypass.
Security teams should learn from this incident and adopt best practices for PAM configurations. Regular audits and penetration tests should be standard procedures to uncover similar vulnerabilities, ensuring robust defenses are in place.
For further reading on securing authentication mechanisms, organizations can explore authentication bypass risks and the importance of a comprehensive security posture.
Moreover, organizations should consider engaging in red teaming services to simulate real-world attack scenarios and improve overall security resilience.
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
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