CVE-2017-9903 in XnView Classic
Summary
by MITRE
XnView Classic for Windows Version 2.40 allows remote attackers to execute code via a crafted .fpx file, related to "Data from Faulting Address controls Code Flow starting at Xfpx+0x00000000000117ff."
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Analysis
by VulDB Data Team • 10/23/2019
The vulnerability CVE-2017-9903 represents a critical remote code execution flaw in XnView Classic for Windows version 2.40 that demonstrates a classic buffer overflow condition within the application's handling of .fpx image files. This file format vulnerability specifically affects the Xfpx component of the software, where a faulting address controls code flow at offset 0x00000000000117ff, indicating a precise memory corruption point that attackers can exploit to gain arbitrary code execution privileges. The flaw stems from inadequate input validation and memory management within the image parsing routines, creating a dangerous condition where malformed data can overwrite critical execution pointers or return addresses.
The technical exploitation of this vulnerability follows a well-established pattern that aligns with CWE-121, which describes heap-based buffer overflow conditions, and CWE-125, which covers out-of-bounds read vulnerabilities. Attackers can craft malicious .fpx files that, when opened by the vulnerable XnView Classic application, trigger a stack-based buffer overflow or heap corruption that allows them to manipulate the program's execution flow. The specific offset 0x00000000000117ff indicates that the faulting address is located within the Xfpx module, suggesting that the vulnerability exists in the image format parser's handling of specific frame data structures or metadata within the .fpx container format. This type of vulnerability directly maps to ATT&CK technique T1059.007, which describes the use of scripting languages and command execution through file format parsing.
The operational impact of CVE-2017-9903 extends beyond simple remote code execution, as it represents a complete compromise of the target system where attackers can execute arbitrary commands with the privileges of the user running XnView Classic. This vulnerability affects systems where the application is installed and configured to automatically open or preview image files, making it particularly dangerous in enterprise environments where users may inadvertently open malicious attachments or browse compromised websites. The vulnerability's remote exploitation capability means that attackers do not need physical access to the target system, allowing for widespread compromise through email attachments, web-based file sharing, or malicious websites. Organizations using XnView Classic in their image processing workflows face significant risk, as this vulnerability can be leveraged for privilege escalation, data exfiltration, or as a foothold for further network infiltration.
Mitigation strategies for CVE-2017-9903 should focus on immediate patching of the vulnerable XnView Classic application to version 2.41 or later, which contains the necessary memory management fixes and input validation improvements. System administrators should implement strict file type filtering and disable automatic preview of potentially malicious file formats, particularly .fpx files that are not essential to business operations. Network-based defenses should include deep packet inspection rules that identify and block .fpx files from suspicious sources, while endpoint protection solutions should be configured to monitor for unusual file access patterns or memory corruption behaviors. The vulnerability also highlights the importance of input sanitization and proper memory management practices, with organizations implementing code review processes that specifically address buffer overflow conditions and address-based code flow control mechanisms. Additionally, users should be educated about the risks of opening untrusted image files and the importance of maintaining updated software versions to prevent exploitation of known vulnerabilities.