CVE-2014-9556 in libmspack
Summary
by MITRE
Integer overflow in the qtmd_decompress function in libmspack 0.4 allows remote attackers to cause a denial of service (hang) via a crafted CAB file, which triggers an infinite loop.
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Analysis
by VulDB Data Team • 04/12/2022
The vulnerability identified as CVE-2014-9556 represents a critical integer overflow flaw within the qtmd_decompress function of libmspack version 0.4, a library widely used for decompressing Microsoft CAB files and other archive formats. This vulnerability resides in the fundamental decompression logic that processes compressed data streams, specifically targeting the handling of size parameters during decompression operations. The flaw manifests when the library encounters malformed CAB files that contain crafted integer values exceeding the maximum representable value for the target data type, causing the decompression process to behave unpredictably.
The technical implementation of this vulnerability exploits the lack of proper input validation and overflow checking within the decompression algorithm. When the qtmd_decompress function processes a specially crafted CAB file, it attempts to calculate buffer sizes or loop counters using arithmetic operations that result in integer overflow conditions. This overflow causes the loop control variables to wrap around to extremely large values, leading to an infinite loop scenario where the decompression process becomes stuck in a perpetual iteration. The vulnerability is particularly dangerous because it can be triggered remotely through network-based file transfers or by simply opening a malicious CAB file, making it a significant threat to applications that rely on libmspack for archive processing.
From an operational perspective, this vulnerability creates a reliable denial of service condition that can be exploited by remote attackers to consume system resources indefinitely. The infinite loop behavior causes the affected application to hang completely, rendering it unresponsive to further requests and effectively denying service to legitimate users. This type of vulnerability is particularly concerning in server environments where multiple concurrent decompression operations might be occurring, as a single malicious file could potentially bring down entire services or cause cascading failures. The impact extends beyond simple resource exhaustion to include potential system instability and service disruption across various applications that utilize libmspack for archive handling.
The vulnerability aligns with CWE-190, which specifically addresses integer overflow and underflow conditions, and demonstrates how improper integer handling can lead to severe operational consequences. From an attack framework perspective, this vulnerability maps to the ATT&CK technique T1499.004, which covers network denial of service attacks through resource exhaustion. The flaw represents a classic example of how decompression algorithms can become attack vectors when proper input validation and boundary checking are omitted. Organizations using libmspack version 0.4 should immediately implement mitigation strategies including input validation, decompression timeout mechanisms, and application sandboxing to prevent exploitation. The recommended solution involves upgrading to a patched version of libmspack that includes proper integer overflow checking and bounds validation, along with implementing defensive programming practices such as using safe arithmetic operations and comprehensive input sanitization to prevent similar vulnerabilities from manifesting in other components.