CVE-2017-8381 in XnView Classic
Summary
by MITRE
XnView Classic for Windows Version 2.40 allows user-assisted remote attackers to execute code via a crafted .mkv file that is mishandled during the opening of a directory in "Browser" mode, because of a "User Mode Write AV near NULL" in XnView.exe.
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Analysis
by VulDB Data Team • 07/01/2020
The vulnerability identified as CVE-2017-8381 affects XnView Classic for Windows version 2.40 and represents a critical code execution flaw that can be exploited by remote attackers with user assistance. This vulnerability manifests when a maliciously crafted .mkv file is processed during directory browsing operations in the application's Browser mode, creating a dangerous scenario where legitimate user interactions can lead to arbitrary code execution on the target system.
The technical root cause of this vulnerability lies in a "User Mode Write AV near NULL" condition within XnView.exe, which is a type of access violation error that occurs when the application attempts to write to a memory location near null pointer addresses. This specific memory handling flaw falls under the category of memory corruption vulnerabilities and is classified as CWE-125 in the Common Weakness Enumeration catalog, representing an out-of-bounds write condition. The vulnerability specifically occurs during the file processing phase when XnView attempts to open directories in Browser mode, suggesting that the application's media file parsing logic fails to properly validate or sanitize the structure of the crafted .mkv file.
The operational impact of this vulnerability extends beyond simple code execution, as it provides attackers with a pathway to compromise systems through social engineering or user interaction. Attackers can deliver malicious .mkv files through various means including email attachments, compromised websites, or file sharing platforms, requiring only that a victim open the directory containing the file in XnView's Browser mode. This user-assisted remote exploitation model reduces the attack surface complexity while maintaining significant risk potential, as it leverages the trust users place in legitimate media viewing applications. The vulnerability demonstrates characteristics consistent with the attack technique described in the MITRE ATT&CK framework under T1059 for command and scripting interpreter, as successful exploitation would allow attackers to execute arbitrary commands on the compromised system.
Mitigation strategies for CVE-2017-8381 should focus on immediate patch management and operational security measures. Users should immediately update to the latest version of XnView Classic where the vulnerability has been addressed through proper memory validation and input sanitization. System administrators should implement network-level controls to restrict access to potentially malicious file types and consider deploying application whitelisting solutions to prevent unauthorized execution of vulnerable applications. Additionally, security awareness training should emphasize the importance of not opening suspicious files in media applications, particularly when the files originate from untrusted sources. The vulnerability highlights the importance of robust input validation and memory safety practices in multimedia applications, as similar flaws could exist in other file processing components that handle user-supplied content without proper boundary checks. Organizations should also consider implementing sandboxing mechanisms for file browsing operations and establishing regular vulnerability assessment procedures to identify and remediate similar memory corruption issues in other applications.