CVE-2018-7587 in CImg
Summary
by MITRE
An issue was discovered in CImg v.220. DoS occurs when loading a crafted bmp image that triggers an allocation failure in load_bmp in CImg.h.
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Analysis
by VulDB Data Team • 02/16/2023
The vulnerability identified as CVE-2018-7587 represents a denial of service condition within the CImg library version 220, specifically when processing maliciously crafted bitmap image files. This issue stems from insufficient input validation and error handling mechanisms within the library's bitmap loading functionality, creating a scenario where an attacker can deliberately construct a malformed bmp file that causes the application to fail during the image loading process. The vulnerability resides in the load_bmp function within the CImg.h header file, which lacks proper bounds checking and memory allocation validation when processing image data structures. When the library attempts to parse the malicious bitmap file, it encounters unexpected data patterns that lead to memory allocation failures, ultimately resulting in application termination or system instability. This type of vulnerability falls under the category of memory allocation failure conditions that can be exploited to cause denial of service attacks against systems relying on the affected library.
The technical flaw manifests through improper handling of memory allocation requests during bitmap file parsing operations. When CImg processes a crafted bmp image, the library's load_bmp function attempts to allocate memory blocks based on data extracted from the image header fields without adequate validation of these values. Maliciously constructed bitmap files can contain oversized or malformed dimension values that cause the allocation routine to either request memory that exceeds system limits or attempt to allocate memory in invalid ways. This failure mode typically occurs when the library computes memory requirements based on corrupted or manipulated header data, leading to allocation failures that are not properly caught or handled by the application code. The vulnerability demonstrates characteristics consistent with CWE-129 Input Validation and the broader category of CWE-704 Incorrect Calculation, where improper handling of input data leads to resource exhaustion or allocation failures. The attack surface is particularly concerning as it can be triggered through any application that utilizes the CImg library for image processing, making it a widespread potential vector for denial of service attacks.
The operational impact of CVE-2018-7587 extends beyond simple application crashes, as it can be leveraged to disrupt services in environments where CImg is integrated into critical systems. Applications that process user-uploaded images or handle external bitmap data become vulnerable to this attack vector, potentially allowing adversaries to cause service interruptions or system instability. The vulnerability is particularly dangerous in web applications, image processing services, or any system where automated image handling occurs, as a single malicious image file can cause cascading failures across multiple processes or services. The attack requires minimal sophistication as it only requires the ability to upload or provide a specially crafted bmp file to the target system, making it accessible to attackers with basic technical capabilities. This vulnerability can be particularly problematic in environments where image processing is automated or batch-processed, as a single malicious file can cause entire processing pipelines to fail, leading to extended service outages and potential data loss. The impact is further amplified by the fact that the vulnerability affects the core image loading functionality, meaning that any application using CImg for image operations is potentially at risk.
Mitigation strategies for CVE-2018-7587 should focus on both immediate defensive measures and long-term architectural improvements. The most effective immediate solution involves upgrading to a patched version of the CImg library where proper input validation and error handling have been implemented to prevent allocation failures during bitmap processing. Organizations should also implement strict input validation at application layers, ensuring that all image files are validated before being passed to the CImg library for processing. Additional protective measures include implementing memory limits and timeouts for image processing operations, as well as deploying sandboxing techniques that isolate image processing components from core application functionality. Network-level defenses such as content filtering and image scanning systems can help identify and block potentially malicious bitmap files before they reach vulnerable applications. Security practices should also include regular vulnerability assessments of third-party libraries and maintaining up-to-date dependency management processes. From a threat modeling perspective, this vulnerability aligns with ATT&CK technique T1499.004 for Denial of Service via Resource Consumption, where attackers exploit library-level flaws to consume system resources or cause application failures. The implementation of proper error handling and graceful degradation mechanisms within applications using CImg can significantly reduce the attack surface and ensure that even if a malicious file is processed, the overall system remains stable and operational.