CVE-2016-2451 in Android
Summary
by MITRE
codecs/on2/dec/SoftVPX.cpp in libstagefright in mediaserver in Android 4.x before 4.4.4, 5.0.x before 5.0.2, 5.1.x before 5.1.1, and 6.x before 2016-05-01 does not validate VPX output buffer sizes, which allows attackers to gain privileges via a crafted application, as demonstrated by obtaining Signature or SignatureOrSystem access, aka internal bug 27597103.
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Analysis
by VulDB Data Team • 07/27/2022
The vulnerability identified as CVE-2016-2451 resides within the libstagefright media framework of Android operating systems, specifically in the VPX decoder component located at codecs/on2/dec/SoftVPX.cpp. This flaw represents a critical buffer overflow condition that affects multiple Android versions including 4.x before 4.4.4, 5.0.x before 5.0.2, 5.1.x before 5.1.1, and 6.x before the specified date. The vulnerability stems from inadequate validation of VPX output buffer sizes during video decoding operations, creating a pathway for privilege escalation attacks that can result in system-level access. The issue is particularly concerning because it allows remote code execution through malicious media files that can be processed by the affected media server component.
The technical implementation of this vulnerability involves the improper handling of buffer size parameters within the SoftVPX.cpp file, which is part of the Stagefright multimedia framework. When processing VPX encoded video streams, the decoder fails to properly validate the size of output buffers before writing decoded data. This validation gap enables attackers to craft malicious VPX media files that contain oversized buffer size specifications, causing memory corruption when the decoder attempts to write data beyond allocated memory boundaries. The flaw aligns with CWE-129, which addresses improper validation of buffer sizes, and represents a classic example of an out-of-bounds write vulnerability that can be exploited to execute arbitrary code with elevated privileges.
From an operational perspective, this vulnerability poses significant security risks as it can be exploited through various attack vectors including malicious email attachments, web downloads, or media files shared through social networks. The attack requires minimal user interaction since the exploitation occurs during automatic media processing by the Android media server, making it particularly dangerous in mobile environments. Successful exploitation can result in obtaining Signature or SignatureOrSystem access levels, which grants attackers the ability to install applications with system-level privileges, access sensitive system resources, and potentially compromise the entire device. This vulnerability demonstrates the critical nature of media processing components in mobile operating systems, as they often run with elevated privileges and process untrusted input from various sources.
The impact of CVE-2016-2451 extends beyond individual device compromise to potentially affect entire mobile ecosystems, as the vulnerability exists in core Android framework components that are widely deployed across different manufacturers and device models. Attackers can leverage this vulnerability through the ATT&CK framework's technique T1068, which involves exploiting legitimate credentials or privileges to gain system-level access. The vulnerability also maps to T1203 in ATT&CK, representing the exploitation of software vulnerabilities for privilege escalation. Organizations and users should consider implementing network-level protections, disabling unnecessary media processing features, and applying security patches immediately upon availability. The vulnerability highlights the importance of proper input validation and memory safety practices in multimedia processing components, as these systems often handle untrusted data from external sources and require robust security controls to prevent exploitation.
The remediation approach for this vulnerability involves applying the security patches released by Google as part of their Android security updates, specifically targeting the affected Android versions mentioned in the CVE description. System administrators should prioritize updating devices to Android versions 4.4.4, 5.0.2, 5.1.1, and 2016-05-01 or later, which contain the necessary fixes for the buffer validation issues in the VPX decoder. Additionally, implementing network-based security controls such as content filtering and sandboxing mechanisms can provide additional layers of protection against exploitation attempts. The vulnerability serves as a reminder of the critical importance of security testing and validation in multimedia frameworks, particularly those handling untrusted input from external sources. Organizations should also consider implementing mobile device management solutions that can automatically deploy security patches and monitor for potential exploitation attempts.