CVE-2016-4024 in imlib2
Summary
by MITRE
Integer overflow in imlib2 before 1.4.9 on 32-bit platforms allows remote attackers to execute arbitrary code via large dimensions in an image, which triggers an out-of-bounds heap memory write operation.
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Analysis
by VulDB Data Team • 08/19/2022
The vulnerability identified as CVE-2016-4024 represents a critical integer overflow flaw within the imlib2 image processing library version 1.4.8 and earlier, specifically affecting 32-bit platforms. This vulnerability resides in the library's handling of image dimensions during the parsing and processing of image files, creating a condition where maliciously crafted image files can trigger unexpected behavior in the application using imlib2. The flaw manifests when the library processes image files containing excessively large width and height values that exceed the maximum representable value for a 32-bit signed integer, leading to wraparound behavior in the arithmetic operations.
The technical mechanism behind this vulnerability involves the improper validation of image dimension parameters during the image loading process. When imlib2 encounters image files with dimensions that exceed the maximum value of a 32-bit signed integer, typically 2,147,483,647, the arithmetic operations used to calculate memory allocation or buffer sizes result in integer overflow. This overflow causes the calculated memory requirements to become negative or significantly smaller than expected, leading to the allocation of insufficient memory buffers. Subsequently, when the application attempts to write image data into these improperly sized buffers, it results in out-of-bounds heap memory writes that can be exploited by attackers to achieve arbitrary code execution.
The operational impact of this vulnerability extends beyond simple denial of service scenarios, as it provides remote attackers with the capability to execute arbitrary code on systems running applications that utilize imlib2 for image processing. This vulnerability affects a wide range of applications including web servers, image processing utilities, and desktop applications that rely on imlib2 for handling image files. The exploitability is particularly concerning because it can be triggered through simple image file uploads or viewing operations, requiring minimal user interaction beyond accessing the malicious content. Attackers can craft specially designed image files with oversized dimensions that, when processed by vulnerable applications, will cause the integer overflow and subsequent memory corruption.
This vulnerability aligns with CWE-190, Integer Overflow or Wraparound, and specifically relates to CWE-787, Out-of-bounds Write, which together describe the fundamental flaw of improper integer handling leading to memory corruption. The attack pattern follows the techniques described in the MITRE ATT&CK framework under T1203, Exploitation for Execution, where attackers leverage software vulnerabilities to execute malicious code. The vulnerability affects systems where imlib2 is used in web applications, content management systems, image galleries, and any software that processes user-uploaded images without proper input validation. The 32-bit platform restriction is significant because 32-bit systems have more limited integer ranges compared to 64-bit systems, making them more susceptible to this particular class of overflow attacks.
Mitigation strategies for CVE-2016-4024 primarily involve upgrading to imlib2 version 1.4.9 or later, where the integer overflow has been addressed through proper input validation and boundary checking. Additionally, implementing input sanitization measures such as dimension validation before image processing, setting maximum allowable image dimensions, and employing heap-based memory protection mechanisms can provide defense in depth. Organizations should also consider deploying web application firewalls and implementing proper image file validation to prevent malicious image uploads. The vulnerability highlights the importance of proper integer handling in security-critical applications and serves as a reminder of the need for comprehensive input validation and memory safety practices in image processing libraries.