CVE-2018-11490 in giflib
Summary
by MITRE
The DGifDecompressLine function in dgif_lib.c in GIFLIB (possibly version 3.0.x), as later shipped in cgif.c in sam2p 0.49.4, has a heap-based buffer overflow because a certain "Private->RunningCode - 2" array index is not checked. This will lead to a denial of service or possibly unspecified other impact.
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Analysis
by VulDB Data Team • 03/17/2023
The vulnerability identified as CVE-2018-11490 represents a critical heap-based buffer overflow within the GIFLIB library implementation, specifically within the DGifDecompressLine function located in dgif_lib.c. This flaw exists in version 3.0.x of GIFLIB and was subsequently distributed through the sam2p 0.49.4 package, demonstrating how vulnerabilities can propagate across software ecosystems. The core issue stems from inadequate input validation where the array index calculation "Private->RunningCode - 2" is not properly bounds-checked, creating a scenario where maliciously crafted GIF files can trigger memory corruption during decompression operations.
The technical exploitation of this vulnerability occurs when a GIF file contains malformed data that causes the decompression routine to attempt accessing memory locations beyond the allocated buffer boundaries. This particular buffer overflow manifests as a heap-based vulnerability because the overflow occurs within heap-allocated memory structures rather than stack-based buffers, making it particularly challenging to detect and exploit consistently. The vulnerability's impact extends beyond simple memory corruption, as the unchecked array index calculation can result in arbitrary code execution or complete denial of service conditions depending on the specific memory layout and exploitation circumstances.
From an operational perspective, this vulnerability presents significant risks to systems processing untrusted GIF content, including web servers, image processing applications, and multimedia frameworks that utilize GIFLIB for image handling. The vulnerability can be leveraged by attackers to cause application crashes, leading to denial of service attacks against web services, or potentially achieve remote code execution in scenarios where the application processes GIF files with elevated privileges. The lack of proper bounds checking in the decompression routine means that any application relying on GIFLIB for image processing becomes vulnerable to malicious input, creating a substantial attack surface for threat actors.
Security professionals should consider this vulnerability in the context of the CWE-121 heap-based buffer overflow classification, which specifically addresses issues where insufficient bounds checking leads to memory corruption in heap-allocated structures. The ATT&CK framework categorizes this as a code injection technique under the system binary modification and privilege escalation domains, as exploitation could lead to arbitrary code execution. Mitigation strategies include immediate patching of affected systems, implementing input validation and sanitization for all GIF file processing, and deploying network-based intrusion detection systems that can identify suspicious GIF file patterns. Additionally, organizations should consider implementing application-level sandboxing for image processing operations and establishing robust monitoring protocols to detect potential exploitation attempts through abnormal memory access patterns or service disruptions.