CVE-2017-14034 in libbpg
Summary
by MITRE
The restore_tqb_pixels function in hevc_filter.c in libavcodec, as used in libbpg 0.9.7 and other products, miscalculates a memcpy destination address, which allows remote attackers to cause a denial of service (heap-based buffer over-read and application crash) or possibly have unspecified other impact.
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Analysis
by VulDB Data Team • 12/07/2019
The vulnerability identified as CVE-2017-14034 resides within the hevc_filter.c file of libavcodec, a critical component of the libbpg 0.9.7 library and numerous other multimedia applications. This flaw manifests in the restore_tqb_pixels function where a fundamental miscalculation occurs in determining the destination address for a memcpy operation. The issue represents a classic heap-based buffer over-read condition that can be exploited remotely, potentially leading to application instability and system crashes. The vulnerability affects multimedia processing systems that utilize HEVC (H.265) video decoding capabilities, making it particularly concerning for streaming services, media players, and content processing platforms.
The technical root cause of this vulnerability stems from improper pointer arithmetic within the restore_tqb_pixels function, specifically in how the destination address is calculated for memory copying operations. When processing HEVC video frames, the function attempts to restore pixel data from a temporary buffer to its proper location within the decoded frame structure. However, the miscalculation results in the memcpy operation targeting memory locations that extend beyond the allocated buffer boundaries. This error falls under the CWE-121 category of stack-based buffer overflow, though it manifests as a heap-based issue due to the dynamic memory allocation patterns involved in video processing. The vulnerability demonstrates characteristics consistent with CWE-787: Out-of-bounds write, where memory operations extend beyond the boundaries of allocated memory regions.
The operational impact of CVE-2017-14034 extends beyond simple denial of service conditions to potentially enable more sophisticated attack vectors. Remote attackers can craft specially malformed HEVC video streams that trigger the vulnerable code path when processed by affected applications. The heap-based buffer over-read can result in application crashes, system instability, and in some cases, may provide opportunities for information disclosure or arbitrary code execution depending on the specific implementation and memory layout. This vulnerability affects a wide range of multimedia applications including web browsers, media players, and streaming platforms that rely on libavcodec for video decoding. The remote exploitation capability makes it particularly dangerous in environments where users may encounter untrusted video content, such as web browsers or media sharing platforms.
Mitigation strategies for this vulnerability require immediate patching of affected software components, particularly focusing on updating libavcodec to versions that contain the corrected memcpy destination address calculation. System administrators should prioritize updating all applications that utilize libbpg 0.9.7 or vulnerable versions of libavcodec, including media players, streaming services, and content management systems. Additionally, implementing input validation measures and sandboxing techniques can provide defense-in-depth protection against exploitation attempts. Network-level filtering to restrict HEVC content processing where possible, combined with regular security assessments of multimedia processing pipelines, helps reduce the attack surface. Organizations should also consider implementing runtime monitoring to detect anomalous memory access patterns that may indicate exploitation attempts. The vulnerability aligns with ATT&CK technique T1059.007 for command and script interpreter execution, as exploitation may involve crafting malicious video content to trigger the vulnerable code path, and T1486 for data encryption for ransom, should exploitation lead to system compromise.