CVE-2017-9911 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 "Data from Faulting Address is used as one or more arguments in a subsequent Function Call starting at Xfpx+0x0000000000010e81."
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Analysis
by VulDB Data Team • 10/23/2019
The vulnerability identified as CVE-2017-9911 affects XnView Classic for Windows version 2.40 and represents a critical denial of service condition that can be exploited through maliciously crafted .fpx files. This flaw manifests when the application processes specially constructed file format files that contain malformed data structures within the FPX (FlashPix) format. The vulnerability stems from improper input validation and memory handling within the image processing pipeline, specifically in how the software manages data from faulting addresses during file parsing operations.
The technical root cause of this vulnerability lies in the improper handling of memory addresses that become corrupted or invalid during the processing of malicious FPX files. When the XnView application attempts to parse these crafted files, it encounters data at faulting addresses that are subsequently used as arguments in subsequent function calls. This particular execution path begins at Xfpx+0x000000000000010e81, indicating a specific memory offset where the vulnerability manifests. The flaw represents a classic case of improper input validation where the application fails to properly sanitize or validate file content before processing, leading to potential memory corruption and application instability.
From an operational perspective, this vulnerability presents significant risks to users who may unknowingly open maliciously crafted FPX files through the XnView Classic application. The impact extends beyond simple denial of service to potentially enabling more severe consequences including arbitrary code execution or system compromise, depending on the specific exploitation vector. Attackers could leverage this vulnerability by distributing malicious FPX files through various attack vectors including email attachments, compromised websites, or malicious file sharing platforms. The vulnerability affects the core functionality of the image viewer application, making it impossible for users to process legitimate image files while the application remains in a compromised state.
The vulnerability aligns with CWE-125, which describes out-of-bounds read conditions, and CWE-787, which covers out-of-bounds write operations, as the application's handling of malformed data structures can result in memory corruption. This vulnerability also maps to ATT&CK technique T1203, which involves exploiting software vulnerabilities for privilege escalation, and T1059, which covers command and scripting interpreter usage. The attack surface is particularly concerning given that FPX files are legitimate image formats that users might encounter in normal operations, making this a particularly dangerous vulnerability for widespread exploitation.
Mitigation strategies for CVE-2017-9911 should include immediate patching of XnView Classic to version 2.41 or later, which contains the necessary fixes for proper input validation and memory handling. System administrators should implement strict file validation policies that prevent automatic execution of potentially malicious files, particularly those with .fpx extensions. Network-based protections such as email filtering, web application firewalls, and endpoint detection systems should be configured to scan and block suspicious FPX files. Users should be educated about the risks of opening files from untrusted sources and should be encouraged to verify file integrity before processing. Additionally, organizations should consider implementing application whitelisting policies that restrict execution of specific versions of XnView Classic that are known to contain this vulnerability. The most effective long-term solution involves upgrading to newer versions of image processing software that have been properly hardened against such memory corruption vulnerabilities.