CVE-2016-7800 in GraphicsMagick
Summary
by MITRE
Integer underflow in the parse8BIM function in coders/meta.c in GraphicsMagick 1.3.25 and earlier allows remote attackers to cause a denial of service (application crash) via a crafted 8BIM chunk, which triggers a heap-based buffer overflow.
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Analysis
by VulDB Data Team • 11/11/2022
The vulnerability identified as CVE-2016-7800 represents a critical integer underflow flaw within GraphicsMagick's metadata parsing functionality that can be exploited to achieve remote denial of service conditions. This issue specifically affects GraphicsMagick versions 1.3.25 and earlier, where the parse8BIM function in the coders/meta.c source file fails to properly validate integer values during the processing of 8BIM chunks. The 8BIM chunk format is commonly used in image files to store metadata information, particularly within Photoshop Document files and other formats that support extended metadata storage. When a maliciously crafted 8BIM chunk is processed, the integer underflow condition causes subsequent buffer operations to overflow heap memory regions, leading to application instability and potential crash scenarios.
The technical implementation of this vulnerability stems from improper input validation within the parse8BIM function where integer arithmetic operations do not account for potential underflow conditions. When processing the 8BIM chunk data, the function performs calculations that assume positive integer values for buffer sizing and memory allocation operations. However, when an attacker supplies crafted data that causes these calculations to result in negative values, the integer underflow occurs. This underflow subsequently leads to heap-based buffer overflows during memory allocation or data copying operations, as the system attempts to allocate memory regions that are either negative or excessively large. The vulnerability is classified as a CWE-190 - Integer Overflow or Wraparound, which is a well-documented weakness in software systems where integer arithmetic operations produce results that exceed the maximum value that can be represented by the data type, leading to unexpected behavior.
From an operational perspective, this vulnerability poses significant risks to systems that process untrusted image files through GraphicsMagick, particularly in web applications, content management systems, and digital asset management platforms. The remote exploitation capability means that attackers can trigger the vulnerability without requiring local access to the system, making it particularly dangerous in environments where users can upload or process external image files. The denial of service impact extends beyond simple application crashes, as the heap corruption can potentially lead to more severe consequences including arbitrary code execution in some scenarios. The vulnerability affects systems that handle image processing workflows, such as web servers processing user-uploaded images, automated image conversion services, and any application that relies on GraphicsMagick for image manipulation and metadata extraction.
Mitigation strategies for CVE-2016-7800 should prioritize immediate patching of GraphicsMagick installations to versions 1.3.26 or later where the integer underflow has been addressed through proper input validation and boundary checking. System administrators should implement comprehensive input validation measures that sanitize all image metadata before processing, particularly focusing on 8BIM chunk data. Network-level protections can include implementing content filtering systems that scan image files for suspicious metadata structures, while application-level defenses should incorporate robust error handling and memory protection mechanisms. The vulnerability aligns with ATT&CK technique T1203 - Exploitation for Client Execution, as it represents a classic case of remote code execution through memory corruption vulnerabilities, and also maps to T1499.004 - Endpoint Denial of Service, highlighting the service disruption potential. Organizations should also consider implementing sandboxing mechanisms for image processing operations and establishing monitoring protocols to detect unusual memory allocation patterns that might indicate exploitation attempts. Additionally, regular security assessments and vulnerability scanning should be conducted to identify other potential integer overflow and underflow conditions within the image processing pipeline.