CVE-2021-25394 in Smart Phone
Summary
by MITRE • 06/11/2021
A use after free vulnerability via race condition in MFC charger driver prior to SMR MAY-2021 Release 1 allows arbitrary write given a radio privilege is compromised.
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Analysis
by VulDB Data Team • 02/14/2025
The vulnerability identified as CVE-2021-25394 represents a critical use after free condition that emerges from a race condition within the MFC charger driver component of mobile device firmware. This flaw specifically affects systems prior to the SMR MAY-2021 Release 1, indicating it was a pre-existing vulnerability that persisted through multiple firmware iterations. The vulnerability's classification as a use after free directly maps to CWE-416, which describes the condition where a program continues to use a pointer after the memory it points to has been freed, potentially leading to unpredictable behavior and exploitation opportunities. The race condition aspect of this vulnerability creates a temporal window where the system's memory management becomes inconsistent, allowing for malicious manipulation of memory pointers.
The operational impact of this vulnerability becomes particularly severe when considering the privilege requirements for exploitation. The flaw necessitates that an attacker already possess radio privilege, which typically represents a high-privilege level access within mobile device security frameworks. This requirement aligns with ATT&CK technique T1068, which covers the exploitation of local privileges to gain elevated access. The combination of radio privilege and the use after free vulnerability creates a dangerous attack surface where an adversary could potentially leverage the race condition to execute arbitrary write operations within the system's memory space. This capability fundamentally undermines the device's memory safety mechanisms and could enable attackers to modify critical system components or inject malicious code.
The technical implementation of this vulnerability stems from improper synchronization mechanisms within the MFC charger driver's memory management routines. When the driver handles concurrent access to charger-related resources, the race condition allows for a scenario where a memory allocation is freed while another process or thread attempts to access the same memory location. This timing issue creates a window where memory corruption can occur, potentially enabling attackers to manipulate memory contents and redirect program execution flow. The arbitrary write capability that results from this vulnerability is particularly concerning as it provides attackers with the ability to modify any memory location within the system's address space, potentially allowing for privilege escalation, data corruption, or complete system compromise.
Mitigation strategies for CVE-2021-25394 should focus on both immediate firmware updates and enhanced security monitoring. Organizations must prioritize applying the SMR MAY-2021 Release 1 or subsequent patches that address the race condition within the MFC charger driver. The vulnerability's nature as a memory safety issue aligns with the principles of the Memory Safety Framework, which emphasizes proper memory management and synchronization techniques. Additionally, implementing robust monitoring for unauthorized radio privilege usage and anomalous memory access patterns can help detect exploitation attempts. Security teams should also consider employing exploit mitigation techniques such as stack canaries, address space layout randomization, and control flow integrity checks to reduce the effectiveness of potential exploitation attempts. The vulnerability's presence in pre-SMR releases indicates the importance of regular security updates and the need for comprehensive firmware security assessments to identify similar race condition vulnerabilities that may exist in other system components.