CVE-2018-7640 in CImg
Summary
by MITRE
An issue was discovered in CImg v.220. A heap-based buffer over-read in load_bmp in CImg.h occurs when loading a crafted bmp image, a different vulnerability than CVE-2018-7588. This is in a Monochrome case, aka case 1.
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Analysis
by VulDB Data Team • 02/16/2023
The vulnerability identified as CVE-2018-7640 represents a critical heap-based buffer over-read flaw within the CImg library version 220, specifically affecting the load_bmp function when processing maliciously crafted bitmap image files. This security weakness resides in the library's handling of monochrome bitmap formats, classified as case 1 within the vulnerability scope. The CImg library serves as a comprehensive open-source image processing framework widely utilized in various software applications for computer graphics operations, making this vulnerability particularly concerning due to its potential for widespread exploitation across multiple platforms and systems that depend on this image processing component.
The technical implementation of this vulnerability stems from improper bounds checking within the bitmap loading mechanism when processing monochrome image data structures. During the parsing of bitmap files, the load_bmp function fails to adequately validate the size parameters of the image data, allowing an attacker to craft a malicious bmp file that triggers a buffer over-read condition. This occurs specifically in monochrome bitmap cases where the expected data format does not match the actual data structure, causing the application to read memory locations beyond the allocated buffer boundaries. The heap-based nature of this vulnerability means that the over-read affects dynamically allocated memory segments, potentially exposing sensitive data or enabling further exploitation techniques that could lead to arbitrary code execution.
The operational impact of CVE-2018-7640 extends beyond simple data corruption, as it can potentially enable attackers to extract information from adjacent memory regions, including potentially sensitive application data, cryptographic keys, or other confidential information stored in memory. Systems utilizing the vulnerable CImg library in applications such as image processing software, computer graphics tools, or any platform that handles bitmap image files become susceptible to this attack vector. The vulnerability particularly affects applications that process untrusted image files without proper input validation, creating a significant risk for web applications, image viewers, and any software that incorporates the CImg library for bitmap handling operations. This type of vulnerability aligns with CWE-125, which describes out-of-bounds read conditions, and can be categorized under ATT&CK technique T1059.007 for command and scripting interpreter usage in exploitation scenarios.
Mitigation strategies for CVE-2018-7640 require immediate action to upgrade to patched versions of the CImg library, with version 221 or later recommended to address the buffer over-read vulnerability. Organizations should implement comprehensive input validation measures when processing image files, particularly focusing on bitmap format handling and ensuring proper bounds checking before memory allocation. Additionally, application developers should consider implementing sandboxing techniques and memory protection mechanisms to limit the potential impact of such vulnerabilities. Regular security assessments and vulnerability scanning should include checks for outdated library versions, while system administrators should monitor for any unauthorized access attempts that may indicate exploitation of this vulnerability. The remediation process should also involve thorough code review of applications that utilize the CImg library to identify and address any potential indirect impacts of this vulnerability on system security posture.