CVE-2020-0499 in Android
Summary
by MITRE • 12/15/2020
In FLAC__bitreader_read_rice_signed_block of bitreader.c, there is a possible out of bounds read due to a heap buffer overflow. This could lead to remote information disclosure with no additional execution privileges needed. User interaction is needed for exploitation.Product: AndroidVersions: Android-11Android ID: A-156076070
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Analysis
by VulDB Data Team • 12/18/2020
The vulnerability identified as CVE-2020-0499 represents a critical heap buffer overflow flaw within the FLAC audio decoding library component of Android systems. This issue exists in the FLAC__bitreader_read_rice_signed_block function located in the bitreader.c source file, where improper bounds checking allows for unauthorized memory access patterns. The vulnerability specifically manifests as an out-of-bounds read condition that can be triggered during the processing of maliciously crafted FLAC audio files. The flaw stems from inadequate validation of input parameters during the bit reading operations that are fundamental to FLAC audio decompression, creating a pathway for attackers to manipulate memory access patterns beyond allocated buffer boundaries.
The operational impact of this vulnerability extends beyond simple memory corruption, as it enables remote information disclosure without requiring any privileged execution contexts or user interaction beyond the initial exploitation trigger. This characteristic places the vulnerability in the category of remotely exploitable flaws that can be leveraged by attackers to extract sensitive information from affected Android devices. The vulnerability affects Android 11 systems and is catalogued under Android ID A-156076070, indicating its classification within the Android security framework. The attack vector requires user interaction to initiate exploitation, typically through the delivery of malicious audio content that triggers the vulnerable code path during normal media playback operations.
From a cybersecurity perspective, this vulnerability aligns with CWE-125, which describes out-of-bounds read conditions that can lead to information disclosure and potential system compromise. The flaw also maps to ATT&CK technique T1059.007, which involves the use of system services and libraries to execute malicious code, as attackers could leverage this vulnerability to extract information from system memory. The buffer overflow condition specifically affects the FLAC bit reader implementation, which is part of the broader audio processing pipeline that handles compressed audio formats. The vulnerability demonstrates how seemingly benign media processing functions can become attack vectors when proper bounds checking mechanisms are absent or insufficient. The exploitation scenario typically involves an attacker crafting a specially formatted FLAC file that, when processed by an affected Android device, triggers the buffer overflow condition and enables information disclosure.
Mitigation strategies for CVE-2020-0499 should prioritize immediate system updates and patches provided by Android security teams, as these address the root cause through proper bounds checking implementations. Organizations should implement network-level controls to restrict access to potentially malicious audio content, particularly in environments where user access to media files cannot be fully controlled. Regular security assessments should include verification of audio processing library versions and implementation of runtime protections that can detect anomalous memory access patterns. The vulnerability underscores the importance of robust input validation in multimedia processing libraries, as these components often handle untrusted data from various sources and must maintain strict memory boundaries to prevent information leakage and potential escalation to more severe compromise scenarios.