CVE-2022-20141 in Android
Summary
by MITRE • 06/15/2022
In ip_check_mc_rcu of igmp.c, there is a possible use after free due to improper locking. This could lead to local escalation of privilege when opening and closing inet sockets with no additional execution privileges needed. User interaction is not needed for exploitation.Product: AndroidVersions: Android kernelAndroid ID: A-112551163References: Upstream kernel
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Analysis
by VulDB Data Team • 06/15/2022
The vulnerability identified as CVE-2022-20141 represents a critical use-after-free condition within the Android kernel's multicast group management implementation. This flaw exists in the ip_check_mc_rcu function located in the igmp.c source file, which handles Internet Group Management Protocol operations for multicast traffic. The issue stems from inadequate locking mechanisms that allow concurrent access to memory resources during socket lifecycle operations, creating a window where freed memory can be accessed by subsequent operations. The vulnerability specifically manifests when inet sockets are opened and closed repeatedly, enabling an attacker to exploit the race condition that occurs during multicast group membership checks. This particular flaw falls under CWE-416, which categorizes use-after-free vulnerabilities, and demonstrates the dangerous consequences of improper synchronization in kernel-level code where memory safety is paramount. The exploitation requires no user interaction and can be achieved through local processes, making it particularly concerning for Android devices where multiple applications and system services may interact with network socket operations.
The technical implementation of this vulnerability involves the improper handling of reference counting and locking mechanisms within the kernel's multicast group management subsystem. When multiple threads or processes attempt to access multicast group membership information simultaneously during socket creation and destruction phases, the RCU (Read-Copy-Update) mechanism fails to provide adequate protection against premature memory deallocation. The ip_check_mc_rcu function performs multicast group validation checks but does not properly synchronize access to the underlying multicast group structures, allowing a malicious process to trigger a race condition where memory allocated for multicast group information gets freed while another thread attempts to read from it. This scenario creates a predictable memory access pattern that can be exploited to overwrite critical kernel memory locations, potentially enabling privilege escalation. The vulnerability is particularly insidious because it leverages legitimate kernel operations to create the exploit conditions, making detection and prevention more challenging. The flaw demonstrates poor adherence to kernel security principles where synchronization primitives should protect all shared data structures during concurrent access scenarios.
The operational impact of CVE-2022-20141 extends beyond simple privilege escalation to potentially enable complete system compromise through the exploitation of kernel memory corruption. An attacker with local access can leverage this vulnerability to execute arbitrary code with kernel-level privileges, effectively bypassing all user-space security controls and access restrictions. The vulnerability's exploitation does not require elevated privileges initially, meaning that any local user or application with basic network access can potentially trigger the condition. This makes the flaw particularly dangerous in multi-user environments where untrusted applications may be running on the device. The attack vector is relatively simple and can be automated through standard socket operations, making it suitable for exploitation in various attack scenarios including mobile malware and privilege escalation attacks. The vulnerability's presence in the Android kernel means that all affected Android devices are potentially vulnerable, regardless of the specific Android version or device manufacturer, as long as the vulnerable kernel code is present.
Mitigation strategies for CVE-2022-20141 focus on both immediate patching and operational security measures. The primary and most effective mitigation involves applying the upstream kernel patch that addresses the improper locking mechanism in the ip_check_mc_rcu function, ensuring that adequate synchronization is maintained during multicast group membership operations. Organizations should prioritize updating their Android devices and kernel implementations to versions containing the fix, particularly for devices that handle sensitive data or operate in high-security environments. Network administrators should also implement monitoring for unusual socket creation and destruction patterns that might indicate exploitation attempts, as the vulnerability can be detected through behavioral analysis of network operations. Additional defensive measures include implementing kernel lockdown features and restricting local application capabilities where possible, though these measures are secondary to the primary patching requirement. The vulnerability's classification under the ATT&CK framework as privilege escalation through kernel exploits emphasizes the need for comprehensive security monitoring and the importance of maintaining up-to-date kernel security patches across all Android devices to prevent exploitation of similar kernel-level vulnerabilities.