CVE-2018-7641 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 "32 bits colors" case, aka case 32.
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Analysis
by VulDB Data Team • 02/16/2023
The vulnerability identified as CVE-2018-7641 represents a critical heap-based buffer over-read flaw within the CImg library version 220. This issue specifically manifests during the processing of BMP image files when the library encounters a crafted malicious file with 32-bit color depth configuration. The vulnerability falls under the broader category of memory safety issues that have plagued image processing libraries for years, demonstrating how seemingly benign file format parsing can become a vector for sophisticated attacks.
The technical implementation of this vulnerability occurs within the load_bmp function of CImg.h, where the library fails to properly validate the dimensions and memory allocation requirements when processing 32-bit color BMP files. This particular flaw affects what is known as "case 32" in the library's internal processing logic, indicating that the vulnerability is specifically triggered when the system attempts to parse BMP files with 32 bits per pixel color representation. The buffer over-read occurs because the library reads beyond the allocated memory boundaries when handling malformed input data, potentially exposing sensitive memory contents to unauthorized access.
From an operational perspective, this vulnerability creates significant risk for applications that utilize the CImg library for image processing tasks, particularly those handling untrusted image files from external sources. Attackers can craft malicious BMP files that, when processed by vulnerable applications, will cause the heap-based buffer over-read to occur, potentially leading to information disclosure, application crashes, or in more severe cases, arbitrary code execution. The vulnerability's impact is amplified because BMP format is widely supported and used across various platforms and applications, making it an attractive target for exploitation. This issue is distinct from CVE-2018-7588, indicating that multiple vulnerabilities exist within the same library version that require separate mitigation approaches.
The vulnerability aligns with CWE-125, which describes "Uninitialized Read" conditions in memory safety contexts, and can be mapped to ATT&CK technique T1059.007 for the potential execution of malicious code through file processing. Organizations using CImg library versions prior to 220 should implement immediate mitigation strategies including input validation, image file sanitization, and application sandboxing. Additionally, upgrading to patched versions of the library or implementing proper bounds checking mechanisms within the application code provides the most effective long-term solution to address this heap-based buffer over-read vulnerability.