CVE-2021-25344 in Mobile Device
Summary
by MITRE • 03/05/2021
Missing permission check in knox_custom service prior to SMR Mar-2021 Release 1 allows attackers to gain access to device's serial number without permission.
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Analysis
by VulDB Data Team • 03/28/2021
The vulnerability identified as CVE-2021-25344 represents a critical authorization flaw within the knox_custom service component of Samsung mobile devices. This issue affects devices prior to the SMR Mar-2021 Release 1 security patch, where the service fails to properly validate user permissions before exposing sensitive device information. The vulnerability stems from inadequate access control mechanisms that allow unauthorized applications or malicious actors to bypass normal permission boundaries and retrieve the device's serial number. This represents a fundamental breakdown in the principle of least privilege where sensitive system information should be protected from unauthorized access. The flaw exists at the service level where the knox_custom service should enforce proper authentication and authorization checks before responding to requests for device identification data.
The technical implementation of this vulnerability involves a missing permission check within the knox_custom service daemon that handles device serial number retrieval operations. When applications or processes request the device serial number, the service does not verify whether the requesting entity has appropriate permissions or capabilities to access this information. This allows any application with basic system access to obtain the serial number without proper authorization, effectively creating an information disclosure vulnerability. The flaw aligns with CWE-284 which describes inadequate access control mechanisms and represents a clear violation of the Android security model where device identifiers should be protected from unauthorized access. The vulnerability can be exploited through various attack vectors including malicious applications installed on the device or through compromised system services that can make unauthorized calls to the knox_custom service.
The operational impact of CVE-2021-25344 extends beyond simple information disclosure as the device serial number serves as a critical identifier for device tracking, warranty management, and security enforcement. Attackers who can obtain serial numbers can potentially correlate this information with other data breaches, track device ownership, or use it to target specific devices in further attacks. The vulnerability creates a persistent threat vector where malicious actors can gather device fingerprints and potentially exploit other vulnerabilities that may be associated with specific device models or serial ranges. From an attacker perspective, this represents a low-effort, high-value information gathering mechanism that can be used in conjunction with other exploits to establish persistent access or conduct targeted attacks. The vulnerability also impacts Samsung's Knox security platform which relies on proper access controls to maintain device integrity and protect enterprise data.
Mitigation strategies for CVE-2021-25344 require immediate implementation of the SMR Mar-2021 Release 1 security patches provided by Samsung to address the underlying permission check deficiencies. Organizations should ensure all affected devices receive the appropriate security updates and monitor for any unauthorized applications that may attempt to exploit this vulnerability. System administrators should implement device management policies that restrict application installation and monitor for suspicious behavior patterns that may indicate exploitation attempts. The vulnerability demonstrates the importance of proper service-level access controls and highlights the need for comprehensive security testing of system services before deployment. Security teams should conduct vulnerability assessments to identify other services that may exhibit similar permission check deficiencies and implement appropriate access control measures. From an ATT&CK framework perspective, this vulnerability maps to techniques involving privilege escalation and information gathering, with potential for lateral movement if the serial number information is used to correlate with other device-specific vulnerabilities or attack vectors.