CVE-2021-39620 in Android
Summary
by MITRE • 01/14/2022
In ipcSetDataReference of Parcel.cpp, there is a possible way to corrupt memory due to a use after free. This could lead to local escalation of privilege with no additional execution privileges needed. User interaction is not needed for exploitation.Product: AndroidVersions: Android-11 Android-12Android ID: A-203847542
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Analysis
by VulDB Data Team • 01/19/2022
The vulnerability identified as CVE-2021-39620 resides within the Android operating system's inter-process communication framework, specifically in the ipcSetDataReference function located in Parcel.cpp. This flaw represents a critical memory corruption issue that stems from improper handling of memory references during inter-process communication operations. The vulnerability is classified as a use-after-free condition, where memory that has been freed is accessed or modified, potentially leading to unpredictable behavior and system instability. Such memory corruption vulnerabilities are particularly dangerous in system-level components like the Android IPC framework, as they can be exploited to gain unauthorized access to system resources and privileges.
The technical implementation of this vulnerability occurs within the Android runtime environment where processes communicate through the Binder driver and Parcel objects. When ipcSetDataReference processes data references, it fails to properly validate or manage the lifecycle of memory allocations, creating opportunities for attackers to manipulate memory contents after objects have been freed. This particular flaw affects Android versions 11 and 12, indicating it was present in the system's core communication infrastructure and could be exploited without requiring any user interaction or additional privileges beyond what is normally available to applications. The use-after-free condition specifically manifests when the system attempts to reference memory that has already been deallocated, potentially allowing for arbitrary code execution or privilege escalation.
The operational impact of this vulnerability is significant as it enables local privilege escalation without requiring any special user interaction or additional execution privileges. An attacker with access to a regular application context could potentially exploit this vulnerability to elevate their privileges to system level, gaining access to sensitive system resources and capabilities. This represents a serious security concern for Android devices, as it undermines the fundamental security model that separates user applications from system processes. The vulnerability's exploitation potential is amplified by its location within the core IPC mechanisms, making it a prime target for attackers seeking to establish persistent access or perform more sophisticated attacks within the device's security boundaries. According to CWE classification, this vulnerability maps to CWE-416 Use After Free, which is categorized as a memory safety issue with high severity implications.
The exploitation of this vulnerability aligns with ATT&CK techniques related to privilege escalation and persistence within mobile environments. Attackers could leverage this flaw to gain system-level access, potentially enabling them to modify system files, install malicious applications, or access sensitive user data. The fact that no user interaction is required for exploitation makes this vulnerability particularly concerning from a security perspective, as it can be triggered automatically when applications perform normal IPC operations. Mitigation strategies should focus on patching the affected Android versions, implementing additional memory validation checks, and potentially employing runtime protections to prevent use-after-free conditions in similar system components. Organizations should prioritize immediate patch deployment and monitor for any signs of exploitation attempts, as this vulnerability represents a serious threat to Android device security and could be used as a foundation for more complex attack chains.