CVE-2021-0967 in Android
Summary
by MITRE • 12/15/2021
In vorbis_book_decodev_set of codebook.c, there is a possible out of bounds write due to a missing bounds check. This could lead to remote information disclosure with no additional execution privileges needed. User interaction is needed for exploitation.Product: AndroidVersions: Android-10 Android-11 Android-12 Android-9Android ID: A-199065614
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Analysis
by VulDB Data Team • 12/18/2021
The vulnerability identified as CVE-2021-0967 resides within the vorbis_book_decodev_set function in the codebook.c file of the Android media processing framework. This flaw represents a critical out-of-bounds write condition that occurs when the system fails to validate array indices before accessing memory locations. The vulnerability is categorized under CWE-129 as an insufficient input validation, specifically manifesting as an improper bounds check during audio codec processing. The affected Android versions span from Android 9 through Android 12, indicating a broad impact across multiple release cycles and suggesting the flaw has persisted for considerable time within the codebase.
The technical exploitation of this vulnerability occurs during the processing of Ogg Vorbis audio files through the Android media framework. When the vorbis_book_decodev_set function attempts to decode audio data, it reads from a codebook structure without verifying that the calculated index values remain within acceptable bounds. This missing validation allows an attacker to craft malicious audio files that, when processed by the Android system, can cause memory corruption. The vulnerability requires user interaction for exploitation, typically through the automatic playback of specially crafted media files or through applications that process audio content without proper sanitization.
The operational impact of CVE-2021-0967 extends beyond simple memory corruption to potentially enable remote information disclosure attacks. While the vulnerability does not require additional execution privileges, it can be leveraged to extract sensitive data from memory locations accessible to the compromised process. This capability aligns with ATT&CK technique T1005 as it involves data hijacking through memory corruption. The attack vector through media processing represents a significant concern for Android devices since audio files are frequently encountered in daily usage scenarios, making user interaction relatively easy to achieve. The vulnerability's presence in the core media processing libraries means that any application or system component that handles Ogg Vorbis audio content could be exploited.
Mitigation strategies for CVE-2021-0967 should prioritize immediate patching of affected Android versions through official security updates provided by Google. Organizations should implement proactive monitoring of Android device firmware versions and ensure timely deployment of security patches. Network-level defenses can include content filtering to prevent the delivery of potentially malicious audio files, though this approach has limitations given the widespread use of standard audio formats. The vulnerability's classification as a remote information disclosure threat necessitates comprehensive device management policies that enforce automatic security updates and regular vulnerability assessments. Additionally, developers should implement input sanitization practices in their applications that process audio content, including bounds checking and proper error handling for media decoding operations.