CVE-2018-11212 in Internet Directory
Summary
by MITRE
An issue was discovered in libjpeg 9a and 9d. The alloc_sarray function in jmemmgr.c allows remote attackers to cause a denial of service (divide-by-zero error) via a crafted file.
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Analysis
by VulDB Data Team • 08/14/2024
The vulnerability identified as CVE-2018-11212 represents a critical denial of service flaw within the libjpeg library version 9a and 9d, specifically affecting the alloc_sarray function located in jmemmgr.c. This issue arises from inadequate input validation when processing specially crafted jpeg files that contain malformed data structures. The vulnerability manifests as a divide-by-zero error during memory allocation operations, which occurs when the library attempts to calculate array dimensions based on corrupted header information provided by the malicious file. Such a scenario can be exploited by remote attackers who craft malicious jpeg files designed to trigger this specific error condition, causing the target application to crash or become unresponsive.
The technical exploitation of this vulnerability stems from the library's failure to properly validate image dimensions and memory allocation parameters before proceeding with memory management operations. When the alloc_sarray function processes a jpeg file with malformed dimension data, it attempts to perform arithmetic operations that result in division by zero, leading to immediate program termination. This behavior aligns with CWE-369, which categorizes divide-by-zero vulnerabilities as a common weakness that can lead to denial of service conditions. The flaw demonstrates a classic lack of proper error handling and input sanitization within the memory management subsystem of the jpeg library, where the code assumes valid input parameters without adequate validation checks.
From an operational impact perspective, this vulnerability poses significant risks to systems that rely on libjpeg for image processing, including web servers, image processing applications, and content management systems that accept user-uploaded jpeg files. The remote nature of the attack means that malicious actors can exploit this vulnerability without requiring local access or authentication, making it particularly dangerous in web-facing environments. When exploited, the vulnerability can cause cascading failures in applications that depend on libjpeg, potentially leading to widespread service disruption. The attack vector is particularly concerning because jpeg files are commonly used in web applications, making this vulnerability a prime target for attackers seeking to disrupt services through simple file uploads.
The mitigation strategies for CVE-2018-11212 primarily focus on updating to patched versions of libjpeg where the divide-by-zero condition has been addressed through proper input validation and error handling. System administrators should prioritize updating their libjpeg installations to versions that have been verified to contain the necessary security patches. Additionally, implementing proper input validation at the application level can provide an additional layer of defense by rejecting malformed files before they reach the vulnerable library functions. Network-level protections such as content filtering and file type validation can also help prevent malicious jpeg files from being processed by applications that use libjpeg. Organizations should also consider implementing intrusion detection systems that can identify attempts to exploit this vulnerability through unusual memory allocation patterns or process termination events. The remediation process should include thorough testing of updated libraries to ensure that the fix does not introduce compatibility issues with existing applications while maintaining the security posture against this specific denial of service threat.