CVE-2016-20025 in ZKAccess Professional
Summary
by MITRE • 03/16/2026
ZKTeco ZKAccess Professional 3.5.3 contains an insecure file permissions vulnerability that allows authenticated users to escalate privileges by modifying executable files. Attackers can leverage the Modify permission granted to the Authenticated Users group to replace executable binaries with malicious code for privilege escalation.
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Analysis
by VulDB Data Team • 03/16/2026
The vulnerability identified as CVE-2016-20025 resides within the ZKTeco ZKAccess Professional 3.5.3 software, a biometric access control system widely deployed in enterprise and industrial environments. This security flaw represents a critical privilege escalation vulnerability that exploits weak file permission controls within the application's file system architecture. The vulnerability specifically affects the software's handling of executable files and their associated permission models, creating a pathway for authenticated attackers to gain elevated system privileges. The ZKAccess Professional software is designed to manage access control systems for buildings and facilities, making it a critical component in physical security infrastructure. When properly configured, this system controls access to secure areas through biometric authentication and other security mechanisms, but the file permission vulnerability undermines the integrity of the entire security framework.
The technical flaw manifests through the insecure file permission configuration that grants the Authenticated Users group modify permissions on executable files within the application's directory structure. This design decision violates fundamental security principles by providing unnecessary write access to executable components, particularly in a context where only administrators should possess the capability to modify core system binaries. The vulnerability stems from improper access control implementation where the software does not adequately restrict file modification privileges based on user roles and security requirements. According to CWE-276, this represents a classic case of insecure default permissions, where the system's default configuration provides excessive privileges to users who should only have read access to executable files. The flaw allows an authenticated user to replace legitimate executable binaries with malicious code, effectively bypassing the application's security controls and gaining unauthorized administrative capabilities.
The operational impact of this vulnerability extends beyond simple privilege escalation to encompass potential complete system compromise and unauthorized access to physical security infrastructure. Attackers who successfully exploit this vulnerability can modify critical system components such as authentication modules, access control binaries, and system management tools. This enables them to create persistent backdoors, modify access logs, disable security features, or grant themselves unlimited access to secured facilities. The vulnerability is particularly dangerous in environments where the ZKAccess Professional system controls critical infrastructure access, as it allows attackers to bypass biometric authentication mechanisms and gain physical access to restricted areas. From an attack chain perspective, this vulnerability aligns with ATT&CK technique T1068, which covers privilege escalation through local exploitation, and T1548.001, which addresses abuse of group privileges. The impact is further amplified because the system's legitimate users already possess authentication credentials, making the attack vector more accessible than typical privilege escalation scenarios.
Mitigation strategies for CVE-2016-20025 require immediate implementation of proper file permission controls and access restriction policies. Organizations should immediately review and tighten file permissions on executable files within the ZKAccess Professional installation, ensuring that only authorized administrators possess write access to critical system binaries. The recommended approach involves implementing principle of least privilege by removing unnecessary modify permissions from the Authenticated Users group and other non-administrative user groups. Security administrators should also implement regular permission audits and monitoring of file system changes to detect unauthorized modifications. Additionally, organizations should consider implementing application whitelisting policies to prevent execution of unauthorized binaries, and deploy intrusion detection systems to monitor for suspicious file modification activities. The vulnerability highlights the importance of secure configuration management and proper access control implementation as outlined in security frameworks such as NIST SP 800-53, which emphasizes the need for proper access control and privilege management in security controls. Organizations should also ensure that the ZKAccess Professional software is updated to the latest version that addresses this specific vulnerability, as ZKTeco has likely released patches to correct the insecure file permission configuration.