CVE-2017-12782 in libEBML
Summary
by MITRE
The ReadData function in ebmlmaster.c in libebml2 through 2012-08-26 allows remote attackers to cause a denial of service (assert fault) via a crafted mkv file.
VulDB is the best source for vulnerability data and more expert information about this specific topic.
Analysis
by VulDB Data Team • 01/10/2023
The vulnerability identified as CVE-2017-12782 resides within the libebml2 library, specifically in the ReadData function located in ebmlmaster.c. This library serves as a core component for handling Extensible Binary Meta Language (EBML) formatted data, which is extensively used in multimedia file formats such as Matroska (MKV). The flaw manifests when processing maliciously crafted MKV files that contain malformed EBML data structures, leading to an assertion failure that terminates the application process.
The technical implementation of this vulnerability stems from insufficient input validation within the ReadData function. When the library attempts to parse EBML elements from a malicious MKV file, it encounters malformed data that triggers an assertion check which fails, causing the application to crash. This represents a classic denial of service condition where legitimate users cannot access the service due to the application's abrupt termination. The vulnerability is particularly concerning because MKV files are commonly used in media playback applications, streaming services, and multimedia processing systems, making the attack surface quite broad.
From an operational impact perspective, this vulnerability creates significant risks for applications that rely on libebml2 for processing multimedia content. Attackers can exploit this flaw by crafting specially designed MKV files that, when opened by vulnerable applications, will cause immediate service disruption. The denial of service effect can be particularly damaging in streaming environments, content delivery networks, or media servers where continuous availability is critical. The vulnerability's remote exploitability means that attackers do not need physical access to the target system, making it a serious concern for any networked application that processes user-uploaded media content.
The weakness aligns with CWE-617, which describes reachable assertions, and represents a failure to properly handle malformed input data. From an adversarial perspective, this vulnerability maps to ATT&CK technique T1499.004, which covers network denial of service attacks. The exploit requires minimal sophistication but can cause substantial operational disruption, particularly in environments where multimedia processing is a core function. Organizations should consider implementing input validation layers and robust error handling mechanisms as mitigation strategies, along with regular updates to ensure they are running patched versions of libebml2. Additionally, sandboxing or containerized execution environments for media processing can provide additional protection against exploitation attempts that target this specific vulnerability.