CVE-2017-0556 in Android
Summary
by MITRE
An information disclosure vulnerability in libmpeg2 in Mediaserver could enable a local malicious application to access data outside of its permission levels. This issue is rated as Moderate because it could be used to access data without permission. Product: Android. Versions: 6.0, 6.0.1, 7.0, 7.1.1. Android ID: A-34093952.
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Analysis
by VulDB Data Team • 11/27/2022
The vulnerability CVE-2017-0556 represents a critical information disclosure flaw within the libmpeg2 library component of Android's Mediaserver service. This issue resides in the multimedia processing framework that handles various media file formats including MPEG2 streams. The vulnerability specifically affects Android versions 6.0, 6.0.1, 7.0, and 7.1.1, making it a widespread concern across multiple Android releases. The flaw allows a local malicious application to bypass normal permission boundaries and access data that should be restricted to higher privilege levels. This represents a significant escalation in attack surface since the Mediaserver process typically operates with elevated privileges to handle multimedia processing tasks. The vulnerability stems from improper bounds checking and memory management within the MPEG2 decoding routines, creating potential for unauthorized data exposure through buffer over-read conditions. According to CWE classification, this vulnerability maps to CWE-125: Out-of-bounds Read, which occurs when a program reads data past the end of a valid buffer. The impact is particularly concerning as it enables privilege escalation through information disclosure, allowing attackers to extract sensitive data that may include user credentials, personal information, or application-specific data. The Android ID A-34093952 indicates this was properly tracked within Google's internal vulnerability management system, highlighting the severity assessment by the Android security team. This vulnerability operates at the system level within the media processing pipeline, making it particularly dangerous as it can be exploited by any local application that has access to the device. The exploitation requires local access to the device and does not require network connectivity, making it a local privilege escalation vector that could be leveraged by malware or malicious applications already present on the device. The vulnerability's moderate rating reflects the specific conditions required for exploitation, which include having a local application that can trigger the Mediaserver to process maliciously crafted MPEG2 content. This attack vector aligns with ATT&CK technique T1068: Exploitation for Privilege Escalation, where adversaries exploit software vulnerabilities to gain higher-level privileges. The issue demonstrates a fundamental flaw in the memory management of the libmpeg2 library, where insufficient validation of input data leads to potential information leakage. The vulnerability is particularly relevant in mobile environments where users often install third-party applications that may not be properly vetted for security. From a security architecture perspective, this flaw indicates inadequate sandboxing controls between different privilege levels within the Android media processing framework. The exploitation could potentially expose sensitive information such as cryptographic keys, user authentication tokens, or private application data that resides in memory areas accessible through the vulnerable code path. Security researchers have noted that such vulnerabilities are particularly challenging to detect and prevent because they often occur in well-established multimedia libraries that are widely used across different platforms and applications. The vulnerability's impact extends beyond simple information disclosure as it could serve as a stepping stone for more sophisticated attacks, including credential theft or further privilege escalation within the Android operating system. Organizations and users should consider this vulnerability as part of a broader security assessment, particularly in environments where Android devices handle sensitive information or where device security is paramount. The fix for this vulnerability required updates to the libmpeg2 library implementation to properly validate buffer boundaries and prevent out-of-bounds memory access during MPEG2 stream processing. This type of vulnerability highlights the importance of regular security updates and the need for comprehensive code review processes, especially for libraries that handle untrusted input data. The vulnerability also demonstrates the challenges of maintaining security in complex multimedia frameworks where legacy code may contain undiscovered flaws that can be exploited by malicious actors. Proper mitigation strategies include applying the latest Android security patches, implementing application sandboxing controls, and conducting regular security assessments of media processing components. The vulnerability serves as a reminder of the critical importance of secure coding practices and the need for continuous monitoring of third-party libraries used in mobile operating systems.