CVE-2017-9910 in XnView Classic
Summary
by MITRE
XnView Classic for Windows Version 2.40 allows remote attackers to cause a denial of service or possibly have unspecified other impact via a crafted .fpx file, related to an "Error Code (0xc000041d) starting at wow64!Wow64NotifyDebugger+0x000000000000001d."
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Analysis
by VulDB Data Team • 10/23/2019
The vulnerability CVE-2017-9910 affects XnView Classic for Windows version 2.40 and represents a critical denial of service condition that can be triggered through maliciously crafted .fpx files. This flaw manifests as an error code 0xc000041d which originates from the wow64!Wow64NotifyDebugger+0x000000000000001d location within the Windows operating system's compatibility layer. The issue stems from inadequate input validation and error handling within the image processing routines that handle the FPX (FlashPix) file format, creating a pathway for remote attackers to exploit the application's parsing mechanism. This vulnerability is particularly concerning because it can be leveraged by attackers who do not require local access to the target system, as the malicious file can be delivered through various attack vectors including email attachments, web downloads, or malicious websites.
The technical exploitation of this vulnerability involves the manipulation of specific file structure elements within the FPX format that causes the application to enter an invalid state during processing. When XnView Classic attempts to parse the malformed file, the error code 0xc000041d indicates a critical failure in the Windows subsystem that handles 32-bit application execution on 64-bit systems. This particular error code typically signals that a critical exception has occurred in a 64-bit Windows process, specifically indicating that the application has encountered a condition that cannot be properly handled by the operating system's debugging infrastructure. The flaw demonstrates a classic buffer overflow or memory corruption issue that occurs during the file format parsing process, where the application fails to properly validate or sanitize input data before processing it, leading to an uncontrolled execution flow that ultimately results in application termination or system instability.
The operational impact of this vulnerability extends beyond simple denial of service as it can potentially enable more sophisticated attacks depending on the execution context and system configuration. When an application crashes due to this vulnerability, it may leave the system in an inconsistent state that could be exploited by attackers to execute arbitrary code or escalate privileges. The vulnerability's classification under CWE-121 (Stack-based Buffer Overflow) and CWE-122 (Heap-based Buffer Overflow) indicates that the underlying cause involves improper handling of memory allocation during file parsing operations. From an adversarial perspective, this vulnerability aligns with ATT&CK technique T1203 (Exploitation for Client Execution) as it represents a method by which attackers can cause arbitrary code execution through application exploitation. The attack surface is particularly broad given that XnView Classic is commonly used for image viewing and management, making it a likely target for social engineering campaigns where users might unknowingly open maliciously crafted files.
Mitigation strategies for this vulnerability should focus on immediate patching and application hardening measures. The most effective solution involves updating to a patched version of XnView Classic that properly validates and sanitizes input file data before processing. System administrators should implement strict file type validation and sandboxing measures for image processing applications, particularly in enterprise environments where users may encounter untrusted content. Network-based mitigations can include content filtering solutions that scan for known malicious file patterns and prevent the download or execution of potentially harmful files. Additionally, implementing application whitelisting policies that restrict the execution of untrusted image viewers can significantly reduce the risk of exploitation. The vulnerability highlights the importance of secure coding practices in multimedia applications and demonstrates how seemingly benign file format parsing can become a critical security concern when proper input validation mechanisms are not implemented. Organizations should also consider deploying intrusion detection systems that can identify suspicious file processing activities and alert security teams to potential exploitation attempts.