CVE-2021-0998 in Android
Summary
by MITRE • 12/15/2021
In 'ih264e_find_bskip_params()' of ih264e_me.c, there is a possible out of bounds read due to a heap buffer overflow. This could lead to local information disclosure with no additional execution privileges needed. User interaction is not needed for exploitation.Product: AndroidVersions: Android-12Android ID: A-193442575
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Analysis
by VulDB Data Team • 12/18/2021
The vulnerability identified as CVE-2021-0998 resides within the hardware-accelerated H.264 video encoding component of Android 12 systems, specifically in the ih264e_find_bskip_params function located in the ih264e_me.c source file. This represents a critical heap buffer overflow condition that manifests as an out-of-bounds read during video encoding operations. The flaw occurs when processing video frames for encoding, where insufficient bounds checking allows memory access beyond allocated buffer boundaries. The vulnerability is classified under CWE-125 as an out-of-bounds read, which is a common class of memory safety issues that can lead to information disclosure and system instability.
The technical implementation of this vulnerability stems from inadequate input validation within the video encoding pipeline where the function processes motion estimation parameters for B-frame skipping operations. During normal video encoding operations, the system allocates memory buffers to store intermediate motion estimation data, but the bounds checking logic fails to properly validate the indices used for accessing these buffers. This allows an attacker to potentially read adjacent memory locations containing sensitive information such as kernel memory addresses, stack contents, or other process data. The vulnerability does not require any special privileges or user interaction for exploitation, making it particularly concerning as it can be triggered through normal video encoding operations performed by the system or applications.
From an operational perspective, this vulnerability creates a significant risk for information disclosure attacks within the Android ecosystem. The local information disclosure capability means that any application or process running on the device could potentially exploit this flaw to extract sensitive data from system memory. The impact extends beyond simple information leakage as the read operations could expose memory contents that might aid in developing more sophisticated attacks. The vulnerability affects the entire Android 12 platform and represents a weakness in the hardware acceleration subsystem that processes multimedia content. Attackers could leverage this information to understand system memory layout, potentially enabling further exploitation techniques such as stack or heap spraying attacks.
The mitigation strategies for this vulnerability primarily involve applying the official Android security patches released by Google, which contain the necessary code fixes to address the buffer overflow condition. System administrators should prioritize updating affected Android 12 devices to the latest security patches, particularly those addressing the hardware video encoding components. Additionally, organizations should implement monitoring for unusual video encoding activities that might indicate exploitation attempts. The vulnerability aligns with ATT&CK technique T1059.007 for command and scripting interpreter, as exploitation could potentially lead to further system compromise through information gathering activities. Network administrators should also consider implementing application whitelisting policies to restrict access to video encoding functions where possible, though the vulnerability's local nature limits the effectiveness of network-based mitigations. The fix typically involves implementing proper bounds checking in the affected function and ensuring that all memory accesses are validated against allocated buffer sizes before execution.