CVE-2021-0968 in Android
Summary
by MITRE • 12/15/2021
In osi_malloc and osi_calloc of allocator.cc, there is a possible out of bounds write due to an integer overflow. This could lead to remote code execution with no additional execution privileges needed. User interaction is not needed for exploitation.Product: AndroidVersions: Android-10 Android-11 Android-12 Android-9Android ID: A-197868577
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Analysis
by VulDB Data Team • 12/18/2021
The vulnerability identified as CVE-2021-0968 represents a critical memory safety issue within the Android operating system's memory allocation subsystem. This flaw exists in the osi_malloc and osi_calloc functions located in the allocator.cc source file, which are fundamental components responsible for managing dynamic memory allocation across the Android platform. The vulnerability stems from inadequate input validation and overflow handling mechanisms that fail to properly check for integer overflow conditions during memory allocation operations. This particular flaw is classified under CWE-190 as an integer overflow error, where the system attempts to allocate memory using a value that has been corrupted by an arithmetic overflow, potentially leading to unpredictable behavior and system compromise.
The technical exploitation of this vulnerability occurs when an attacker can manipulate the allocation parameters passed to the memory allocator functions, causing the integer arithmetic to overflow and produce a malicious memory size value. When the system attempts to allocate memory using this corrupted size value, it can result in an out-of-bounds write operation that overflows adjacent memory regions. This type of memory corruption can be leveraged to overwrite critical data structures, function pointers, or return addresses, enabling arbitrary code execution. The vulnerability is particularly dangerous because it requires no additional privileges beyond normal application execution and does not necessitate user interaction for exploitation, making it highly attractive to attackers seeking to compromise Android devices remotely.
From an operational perspective, this vulnerability affects multiple Android versions including Android 9, 10, 11, and 12, indicating it has been present across a significant portion of the Android ecosystem. The impact extends beyond individual applications to potentially compromise the entire operating system, as the memory allocator functions are core system components that are frequently accessed by various system processes and applications. The attack surface is broad since any application or service that invokes memory allocation functions could potentially be exploited, creating a pathway for remote code execution that could allow attackers to gain complete control over affected devices. This vulnerability directly maps to ATT&CK technique T1059.007 for command and scripting interpreter and T1068 for exploit for privilege escalation, as the compromised system could be used to execute malicious code with elevated privileges.
Mitigation strategies for CVE-2021-0968 should prioritize immediate patch deployment through official Android security updates, as these vulnerabilities are typically addressed through memory safety improvements and integer overflow protections. Organizations should implement comprehensive monitoring of system logs for unusual memory allocation patterns or potential exploitation attempts, while also maintaining up-to-date security patches across all Android devices within their environment. The fix typically involves adding proper bounds checking and overflow detection mechanisms to the memory allocation functions, ensuring that input parameters are validated before being used to calculate memory allocation sizes. Additionally, security hardening measures such as stack canaries, address space layout randomization, and memory protection mechanisms should be enabled to reduce the effectiveness of potential exploitation attempts and provide defense-in-depth protection against similar vulnerabilities.