CVE-2024-13966 is a high-severity vulnerability affecting all versions of ZKTeco's BioTime biometric attendance and workforce management software. The core issue is the use of a default password ('123456') that remains unchanged in some deployments, allowing unauthenticated attackers to enumerate valid usernames and subsequently log in as any user who has not updated their password from the default. This vulnerability is categorized under CWE-1393 (Use of Default Password), which highlights the security risk posed by default credentials that are widely known and easily exploitable. The attack vector is network-based (AV:N), requiring no privileges (PR:N), no user interaction (UI:N), and the scope is unchanged (S:U). The impact includes limited confidentiality, integrity, and availability losses (C:L/I:L/A:L), but the ease of exploitation and the ability to impersonate any user make this a significant threat. Since BioTime is used to manage attendance and potentially sensitive employee data, unauthorized access could lead to data leakage, manipulation of attendance records, and disruption of workforce management processes. The lack of authentication requirements and the ability to enumerate usernames exacerbate the risk, enabling attackers to systematically compromise accounts. Although no known exploits are currently reported in the wild, the simplicity of the attack makes it likely that exploitation attempts could emerge quickly if not mitigated.

For European organizations, this vulnerability poses a substantial risk, especially for those relying on ZKTeco BioTime for workforce management and attendance tracking. Unauthorized access could lead to exposure of personal employee information, manipulation of attendance data affecting payroll and compliance, and potential disruption of operational workflows. In sectors with strict data protection regulations such as GDPR, unauthorized data access could result in regulatory penalties and reputational damage. Additionally, compromised credentials could be leveraged as a foothold for lateral movement within corporate networks, increasing the risk of broader compromise. The vulnerability's network exposure and lack of authentication barriers make it particularly dangerous in environments where BioTime is accessible over corporate or public networks without adequate segmentation or access controls.

To mitigate this vulnerability effectively, organizations should immediately enforce a policy requiring all BioTime users to change default passwords upon deployment, specifically updating the 'Self-Password' under the Attendance Settings tab. Network-level protections should be implemented, including restricting access to BioTime interfaces via firewalls or VPNs to trusted IP addresses only. Regular audits should be conducted to identify accounts still using default credentials. Additionally, integrating multi-factor authentication (MFA) where possible can add an extra layer of security. Monitoring and logging access to BioTime systems should be enhanced to detect unusual login attempts or enumeration activities. Vendors and administrators should also stay alert for official patches or updates from ZKTeco and apply them promptly once available. Finally, educating users about the risks of default passwords and enforcing strong password policies will reduce the likelihood of exploitation.