CVE-2018-11657 in ngiflib
Summary
by MITRE
ngiflib.c in MiniUPnP ngiflib 0.4 has an infinite loop in DecodeGifImg and LoadGif.
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Analysis
by VulDB Data Team • 02/11/2020
The vulnerability identified as CVE-2018-11657 resides within the ngiflib component of MiniUPnP version 0.4, specifically in the ngiflib.c file. This issue manifests as an infinite loop during the execution of two critical functions: DecodeGifImg and LoadGif. The flaw represents a classic denial of service vulnerability that can be exploited by malicious actors to disrupt system operations through resource exhaustion. The vulnerability stems from improper handling of GIF image data structures during the decoding process, where malformed or specially crafted GIF files can cause the parser to enter an infinite loop, consuming excessive CPU cycles and potentially leading to system instability or unresponsiveness. This type of vulnerability falls under the category of infinite loop or busy-wait conditions as defined by CWE-835, where a loop lacks proper termination conditions or fails to properly validate input data.
The technical implementation of this vulnerability involves the GIF image format parsing logic within the MiniUPnP library, which is commonly used in network device management and UPnP (Universal Plug and Play) implementations. When the DecodeGifImg and LoadGif functions process certain GIF image data structures, they fail to properly validate the image data or handle edge cases in the GIF format specification. This leads to a scenario where the loop conditions in the parsing algorithm never reach their termination criteria, causing the application to hang indefinitely. The vulnerability is particularly concerning because it can be triggered through legitimate image processing operations, making it difficult to distinguish between normal usage and malicious exploitation. The flaw demonstrates poor input validation practices and inadequate error handling mechanisms that are fundamental to secure coding standards and can be mapped to ATT&CK technique T1499.004 for resource exhaustion attacks.
The operational impact of CVE-2018-11657 extends beyond simple denial of service, as it can affect network infrastructure devices that rely on MiniUPnP for UPnP functionality. Systems running affected versions may experience complete service unavailability when processing malicious GIF images, particularly in environments where image processing is automated or where users can upload content. The vulnerability affects devices such as routers, firewalls, and other network appliances that implement UPnP functionality and may be exploited by attackers to perform persistent denial of service attacks against network services. Organizations using affected software may face operational disruptions that could compromise network availability and potentially impact business continuity. The vulnerability can be exploited through various attack vectors including web-based image uploads, file processing services, or automated scanning of network devices that process GIF images. Given the widespread use of UPnP implementations in consumer and enterprise networking equipment, this vulnerability represents a significant risk to network infrastructure security. Mitigation strategies should include immediate software updates, input validation improvements, and network monitoring to detect potential exploitation attempts. The vulnerability also highlights the importance of proper software testing and security review processes to identify and prevent similar issues in other image processing libraries and network management components that may be susceptible to similar input validation flaws.