CVE-2023-21165 in Android
Summary
by MITRE • 02/16/2024
In DevmemIntUnmapPMR of devicemem_server.c, there is a possible arbitrary code execution due to a use after free. This could lead to local escalation of privilege in the kernel with no additional execution privileges needed. User interaction is not needed for exploitation.
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Analysis
by VulDB Data Team • 12/16/2024
The vulnerability identified as CVE-2023-21165 resides within the kernel-level device memory management subsystem, specifically in the devicemem_server.c source file where the DevmemIntUnmapPMR function handles memory mapping operations. This flaw represents a critical security weakness that allows for local privilege escalation without requiring any user interaction or additional execution privileges, making it particularly dangerous in environments where kernel-level access is typically restricted. The vulnerability manifests as a use-after-free condition that occurs when memory regions are unmapped and subsequently accessed, creating opportunities for malicious code execution within kernel space.
The technical implementation of this vulnerability stems from improper memory management practices within the kernel module responsible for handling device memory operations. When the DevmemIntUnmapPMR function processes memory region unmapping, it fails to properly validate or invalidate references to memory structures that may have already been freed, creating a window where attacker-controlled data can be manipulated to execute arbitrary code. This use-after-free condition falls under the common weakness enumeration CWE-416 which specifically addresses use-after-free vulnerabilities where a pointer is used after the memory it points to has been freed. The vulnerability's exploitation does not require user interaction, meaning it can be triggered automatically through kernel-level operations or by any process with access to the affected device memory interfaces.
The operational impact of CVE-2023-21165 extends far beyond simple privilege escalation, as successful exploitation allows attackers to gain complete control over the kernel execution environment. This creates a pathway for persistent system compromise, enabling adversaries to install rootkits, modify system call tables, disable security mechanisms, or establish backdoor access that persists across reboots. The vulnerability's severity is amplified by its local nature, as it can be exploited by any user with access to the device memory interfaces, potentially allowing attackers to escalate from regular user privileges to full system administrator control. From an attack framework perspective, this vulnerability aligns with ATT&CK technique T1068 which covers local privilege escalation through kernel exploits, and T1543 which covers boot or logon initialization scripts that can be modified through kernel-level access.
Mitigation strategies for CVE-2023-21165 must focus on immediate patch deployment from vendors who have released updates addressing the specific memory management flaw in the device memory subsystem. System administrators should implement comprehensive monitoring for unauthorized kernel memory access patterns and ensure that device memory interfaces are properly restricted to authorized processes only. The fix typically involves implementing proper memory validation checks within the DevmemIntUnmapPMR function to prevent access to freed memory regions and proper reference counting mechanisms to ensure memory structures remain valid throughout their intended usage period. Additionally, organizations should conduct thorough vulnerability assessments to identify systems running affected kernel versions and implement access controls that limit exposure to this specific vulnerability, particularly in environments where device memory interfaces are accessible to untrusted users or processes.