CVE-2021-0494 in Android
Summary
by MITRE • 06/11/2021
In memory management driver, there is a possible out of bounds write due to an integer overflow. This could lead to local escalation of privilege with no additional execution privileges needed. User interaction is not needed for exploitation.Product: AndroidVersions: Android SoCAndroid ID: A-183461318
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Analysis
by VulDB Data Team • 06/18/2021
The vulnerability identified as CVE-2021-0494 resides within the memory management driver component of Android operating systems, representing a critical security flaw that enables local privilege escalation. This issue manifests through an integer overflow condition that occurs during memory allocation operations, specifically within the kernel-level memory management subsystem. The flaw affects Android System-on-Chips and has been assigned the Android ID A-183461318, indicating its significance within the Android security framework. The vulnerability exists in the kernel memory management driver where improper bounds checking allows for out-of-bounds write operations to occur.
The technical root cause of this vulnerability stems from an integer overflow condition that occurs when processing memory allocation requests within the kernel memory management driver. When an attacker crafts specific memory allocation parameters, the integer overflow corrupts the memory layout, creating an opportunity for an out-of-bounds write. This condition typically arises when the driver fails to properly validate or sanitize input parameters before performing arithmetic operations that determine memory allocation sizes. The overflow results in a situation where the calculated memory buffer size exceeds the intended boundaries, allowing subsequent write operations to overwrite adjacent memory regions. This behavior aligns with CWE-190, Integer Overflow or Wraparound, which specifically addresses vulnerabilities arising from improper handling of integer arithmetic operations that can lead to memory corruption.
The operational impact of CVE-2021-0494 is severe and directly enables local privilege escalation without requiring any additional execution privileges or user interaction for exploitation. Once an attacker gains access to a device running an affected Android version, they can leverage this vulnerability to elevate their privileges from a regular user context to a system-level privileged context. This escalation allows the attacker to gain full control over the device, access all system resources, and potentially compromise sensitive data. The vulnerability's exploitation does not require user interaction, making it particularly dangerous as it can be triggered automatically through various attack vectors such as malicious applications or compromised system services. The lack of additional execution privileges needed for exploitation means that even a basic application running on the device could potentially trigger this vulnerability, creating a significant threat surface.
From an adversarial perspective, this vulnerability aligns with ATT&CK technique T1068, Exploitation for Privilege Escalation, where attackers can leverage kernel-level vulnerabilities to gain elevated privileges. The flaw's presence in the memory management driver makes it particularly attractive to attackers as it operates at the kernel level, providing the most direct path to system control. The integer overflow condition creates a predictable memory corruption pattern that can be reliably exploited across different Android SoC implementations, making this vulnerability particularly widespread in affected device populations. Security researchers have noted that such memory management driver vulnerabilities often provide attackers with the most straightforward path to system compromise due to the privileged nature of the affected components.
Mitigation strategies for CVE-2021-0494 should focus on immediate patch deployment as provided by Android security updates, which typically include fixes for integer overflow conditions in kernel memory management components. Organizations should prioritize updating affected devices to the latest Android security patches, particularly those addressing memory management driver vulnerabilities. Additionally, implementing runtime protections such as kernel address space layout randomization and stack canaries can provide additional defense-in-depth measures. Device manufacturers should also consider implementing strict input validation for all memory allocation parameters and conducting thorough code reviews of kernel memory management components to identify similar integer overflow conditions. The vulnerability highlights the critical importance of proper integer arithmetic validation in kernel-level code, particularly in memory management subsystems where errors can have catastrophic security implications.