CVE-2018-7638 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 "256 colors" case, aka case 8.
If you want to get the best quality for vulnerability data then you always have to consider VulDB.
Analysis
by VulDB Data Team • 02/16/2023
The vulnerability identified as CVE-2018-7638 represents a critical heap-based buffer over-read condition within the CImg library version 220, specifically manifesting during the processing of BMP image files. This flaw resides in the load_bmp function within the CImg.h header file and demonstrates a particular susceptibility when handling BMP images with 256-color palettes, classified as case 8 within the library's implementation. The vulnerability stems from inadequate bounds checking during the parsing of BMP file headers and color table entries, creating a scenario where the application reads memory beyond the allocated buffer boundaries.
The technical exploitation of this vulnerability occurs when a maliciously crafted BMP image is processed by software utilizing the CImg library. During the loading process, the library fails to properly validate the color table size specified in the BMP header against the actual data available in the file. When processing 256-color BMP files, the library attempts to read color palette entries beyond the allocated memory space, resulting in a buffer over-read condition that can lead to information disclosure, application crashes, or potentially arbitrary code execution depending on the memory layout and exploitation circumstances. This vulnerability is categorized under CWE-125 as an out-of-bounds read, representing a fundamental memory safety issue that violates standard security practices for input validation and bounds checking.
The operational impact of CVE-2018-7638 extends beyond simple application instability, as it creates potential attack vectors for adversaries seeking to compromise systems that utilize the affected CImg library. Applications relying on CImg for image processing, including those in scientific computing, medical imaging, and multimedia applications, become vulnerable to remote code execution or information leakage when processing untrusted BMP files. The vulnerability's classification as a heap-based buffer over-read aligns with ATT&CK technique T1059.007 for command and scripting interpreter, as exploitation could potentially allow attackers to execute malicious code through compromised image processing pipelines, while also mapping to T1068 for exploit for privilege escalation due to potential memory corruption effects.
Mitigation strategies for CVE-2018-7638 should prioritize immediate patching of affected CImg library versions to the latest release containing the fix for buffer over-read conditions in BMP loading functions. System administrators should implement strict input validation measures for all image file processing, including implementing file format signature checks and size limitations before processing. Additionally, deploying sandboxing techniques for image processing operations and using memory protection mechanisms such as stack canaries and address space layout randomization can significantly reduce the exploitation risk. Organizations should also consider implementing network-based intrusion detection systems to monitor for suspicious image file processing activities and maintain comprehensive monitoring of application logs for potential exploitation attempts. The vulnerability highlights the critical importance of proper bounds checking in image parsing libraries and demonstrates why security-conscious development practices must be enforced throughout the software development lifecycle to prevent such memory safety issues from reaching production environments.