CVE-2013-6630 in Chrome
Summary
by MITRE
The get_dht function in jdmarker.c in libjpeg-turbo through 1.3.0, as used in Google Chrome before 31.0.1650.48 and other products, does not set all elements of a certain Huffman value array during the reading of segments that follow Define Huffman Table (DHT) JPEG markers, which allows remote attackers to obtain sensitive information from uninitialized memory locations via a crafted JPEG image.
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Analysis
by VulDB Data Team • 01/10/2022
The vulnerability described in CVE-2013-6630 represents a critical information disclosure flaw within the libjpeg-turbo library implementation of JPEG decompression functionality. This issue specifically affects the get_dht function located in the jdmarker.c file, which processes JPEG markers during image decoding operations. The vulnerability manifests when the library encounters JPEG images containing Define Huffman Table (DHT) markers followed by subsequent segments, creating a scenario where memory initialization becomes incomplete during the parsing process.
The technical root cause of this vulnerability stems from improper memory management within the Huffman table processing logic. When libjpeg-turbo encounters a DHT marker followed by additional segments, the get_dht function fails to initialize all elements of a crucial Huffman value array before proceeding with subsequent operations. This incomplete initialization leaves portions of memory uninitialized, creating potential exposure points where sensitive data from previous operations or system memory contents may persist in the allocated array space. The flaw exists at the intersection of memory management and parsing logic, where the expectation of complete data initialization is not met during the processing of malformed JPEG structures.
This vulnerability has significant operational impact, particularly in web browsers and applications that rely on libjpeg-turbo for image processing. The remote exploitation capability means that attackers can craft malicious JPEG images designed to trigger the uninitialized memory access pattern, potentially allowing them to extract sensitive information from memory locations that should remain private. The vulnerability affects Google Chrome versions prior to 31.0.1650.48, making it particularly concerning for web-based attacks where users might encounter crafted images through various online channels. The information disclosure could potentially include cryptographic keys, user credentials, or other sensitive data that may have resided in the affected memory regions, directly compromising system security and user privacy.
The vulnerability aligns with CWE-119 which describes improper access to memory before the end of a buffer, and represents a classic example of uninitialized memory access that can lead to information disclosure. From an ATT&CK perspective, this vulnerability maps to the T1059.007 technique related to the use of remote code execution through web browsers, and potentially the T1566.001 technique for initial access via malicious web content. The flaw demonstrates how seemingly benign image processing operations can become attack vectors when memory management is not properly enforced during parsing of structured data formats. Organizations should implement immediate patching of affected libjpeg-turbo versions and consider additional security measures such as image validation and content filtering to prevent exploitation of this vulnerability. The remediation process requires updating to libjpeg-turbo version 1.3.1 or later, where the memory initialization issue has been addressed through proper array initialization before processing subsequent JPEG segments.