CVE-2018-19566 in dcraw
Summary
by MITRE
A heap buffer over-read in parse_tiff_ifd in dcraw through 9.28 could be used by attackers able to supply malicious files to crash an application that bundles the dcraw code or leak private information.
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Analysis
by VulDB Data Team • 04/15/2020
The vulnerability identified as CVE-2018-19566 represents a critical heap buffer over-read flaw within the dcraw library version 9.28 and earlier. This issue specifically affects the parse_tiff_ifd function which processes TIFF image file directories and occurs when the library encounters malformed or maliciously crafted TIFF files. The vulnerability stems from inadequate bounds checking during the parsing of image metadata structures, allowing attackers to manipulate memory access patterns that extend beyond allocated heap buffers. Such buffer over-read conditions are particularly dangerous because they can lead to information disclosure or application crashes, making them attractive targets for exploitation in security-sensitive environments.
The technical implementation of this vulnerability resides in the improper handling of TIFF file structure parsing where the dcraw library fails to validate the size and boundaries of image directory entries before accessing memory regions. When processing TIFF files with malformed IFD (Image File Directory) structures, the parser attempts to read beyond the allocated memory boundaries, potentially accessing adjacent heap memory regions. This flaw falls under the Common Weakness Enumeration category CWE-125, which specifically addresses out-of-bounds read vulnerabilities, and represents a classic example of insufficient input validation in binary parsing routines. The vulnerability is particularly concerning because TIFF files are widely used across various applications, from digital photography tools to scientific imaging software, creating numerous potential attack vectors.
The operational impact of CVE-2018-19566 extends beyond simple application crashes to potentially enable information leakage that could expose sensitive data stored in adjacent memory regions. Attackers exploiting this vulnerability could craft malicious TIFF files that, when processed by vulnerable applications, trigger memory access violations leading to denial of service conditions or unintended data disclosure. This makes the vulnerability particularly dangerous in environments where dcraw is integrated into larger applications such as photo editing software, document management systems, or digital asset management platforms. The vulnerability is classified under the MITRE ATT&CK framework as a code injection technique, specifically targeting memory corruption vulnerabilities that can be exploited through file processing operations.
Mitigation strategies for CVE-2018-19566 require immediate patching of affected dcraw library versions to 9.29 or later, where the buffer over-read conditions have been addressed through proper bounds checking and input validation. Organizations should implement comprehensive application security testing that includes fuzzing of file parsing components to identify similar vulnerabilities in their software stacks. Additionally, deployment of defensive measures such as input sanitization, memory protection mechanisms, and application sandboxing can help reduce the impact of potential exploitation attempts. Security teams should also conduct thorough inventory assessments to identify all applications that may be vulnerable due to integration of the affected dcraw library, particularly in environments where users can upload or process external image files. The vulnerability demonstrates the critical importance of maintaining up-to-date third-party libraries and implementing robust input validation practices in security-sensitive applications.