CVE-2020-35534 in LibRaw
Summary
by MITRE • 09/01/2022
In LibRaw, there is a memory corruption vulnerability within the "crxFreeSubbandData()" function (libraw\src\decoders\crx.cpp) when processing cr3 files.
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Analysis
by VulDB Data Team • 10/11/2022
The vulnerability identified as CVE-2020-35534 resides within the LibRaw library, a widely-used open-source software for processing digital camera raw image files. This memory corruption flaw specifically manifests in the crxFreeSubbandData() function located in the libraw/src/decoders directory structure. The issue represents a critical security concern that could potentially allow attackers to execute arbitrary code or cause system instability when processing maliciously crafted raw image files. LibRaw is extensively integrated into various photography applications, image processing software, and digital asset management systems, making this vulnerability particularly dangerous as it could affect a broad spectrum of end-user applications.
The technical nature of this vulnerability stems from improper memory management within the crxFreeSubbandData() function, which is responsible for freeing memory allocated during the processing of compressed raw image data. When the function handles certain malformed input data structures, it fails to properly validate memory pointers or bounds before attempting deallocation operations. This leads to memory corruption scenarios where adjacent memory locations may be overwritten or accessed incorrectly, potentially resulting in heap corruption or use-after-free conditions. The vulnerability aligns with CWE-125, which describes out-of-bounds read conditions, and CWE-416, which covers use-after-free errors. The flaw occurs during the decompression and processing phase of raw image files, particularly those encoded using the Canon CRX format which employs subband decomposition techniques.
The operational impact of this vulnerability extends beyond simple application crashes, as it creates potential attack vectors for remote code execution. When an application utilizing LibRaw processes a specially crafted CRX file containing malformed subband data, the memory corruption can be leveraged to manipulate program execution flow. Attackers could potentially craft malicious raw image files that, when opened by vulnerable applications, trigger the memory corruption and allow for arbitrary code execution on the target system. This threat model aligns with ATT&CK technique T1203, which covers exploitation for execution, and T1059, which covers command and scripting interpreter. The vulnerability affects not only standalone image viewers but also content management systems, photo editing software, and any application that relies on LibRaw for raw image processing capabilities.
Mitigation strategies for CVE-2020-35534 should prioritize immediate patching of affected LibRaw versions, as vendors have released updates addressing the memory corruption issue. System administrators should ensure all applications utilizing LibRaw are updated to the latest stable versions containing the fix. Additionally, implementing input validation and sanitization measures can help reduce the attack surface by filtering malformed raw image files before processing. Network-based defenses such as intrusion detection systems should be configured to monitor for suspicious file processing activities. Organizations should also consider implementing application whitelisting policies and restricting user access to raw image file processing capabilities where possible. The fix typically involves adding proper bounds checking and memory validation before deallocation operations, ensuring that the crxFreeSubbandData() function properly validates all input parameters and memory references before executing cleanup operations.