CVE-2017-9896 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 a "Read Access Violation on Control Flow starting at Xfpx!gffGetFormatInfo+0x0000000000013e8a."
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Analysis
by VulDB Data Team • 10/23/2019
CVE-2017-9896 represents a critical remote code execution vulnerability affecting XnView Classic for Windows version 2.40. This vulnerability stems from a read access violation that occurs during control flow execution within the Xfpx!gffGetFormatInfo function, specifically at offset 0x000000000000013e8a. The flaw manifests when the application processes a specially crafted .fpx file, which is a format used for storing image data in the XnView image viewer. The vulnerability is classified under CWE-125 as an out-of-bounds read, where the application fails to properly validate input data before attempting to access memory locations. This type of vulnerability falls squarely within the ATT&CK matrix under T1203 - Exploitation for Client Execution, as it enables attackers to execute arbitrary code on vulnerable systems through malicious file manipulation. The technical nature of this flaw indicates that the application does not adequately sanitize or validate the structure of .fpx files, allowing an attacker to craft a file that triggers memory corruption during the format information retrieval process. When a user opens the malicious .fpx file, the application's handling of the malformed data causes a buffer overrun that results in a control flow violation, ultimately enabling remote code execution. The operational impact of this vulnerability is severe as it allows attackers to execute arbitrary code with the privileges of the victim user, potentially leading to complete system compromise. The vulnerability's exploitability is enhanced by the fact that it requires no user interaction beyond opening the malicious file, making it particularly dangerous in phishing scenarios or when users unknowingly open attachments. This flaw affects systems where XnView Classic is installed and is particularly concerning given that the application is widely used for viewing various image formats, making it a common target for attackers seeking to gain unauthorized access to systems. The vulnerability demonstrates the importance of proper input validation and memory management in multimedia applications, as even legitimate file format parsing can become a vector for exploitation. The flaw highlights a critical gap in the application's defensive measures, particularly in how it handles potentially malicious input data during the image format analysis phase. Organizations should prioritize patching this vulnerability as it represents a significant risk to system security and could be exploited in targeted attacks against unsuspecting users.
The vulnerability's classification as a control flow violation indicates that the application's execution path becomes compromised during the parsing of the malicious .fpx file. This type of vulnerability is particularly dangerous because it can be exploited to redirect program execution to attacker-controlled code, bypassing standard security mechanisms. The specific location of the vulnerability within the Xfpx!gffGetFormatInfo function suggests that the issue occurs during the initial analysis phase when the application attempts to determine the format characteristics of the image file. This is consistent with the ATT&CK technique T1059 - Command and Scripting Interpreter, as the vulnerability enables execution of arbitrary commands through the manipulation of the application's internal processing logic. The out-of-bounds read condition creates a situation where the application attempts to access memory locations that are not properly allocated or validated, leading to potential memory corruption that can be leveraged for code execution. This vulnerability is particularly concerning because it affects a widely used image viewing application, meaning that a successful exploitation could potentially compromise a large number of systems. The attack vector is straightforward - an attacker only needs to deliver a malicious .fpx file to a victim who has XnView Classic installed, making this vulnerability particularly dangerous in environments where users frequently open email attachments or download files from untrusted sources. The vulnerability's impact extends beyond simple code execution to potentially enable privilege escalation, depending on the execution context and user privileges. Security professionals should consider this vulnerability as part of a broader threat landscape where multimedia applications represent common attack surfaces. The flaw demonstrates the critical importance of input validation in applications that process user-supplied data, particularly in file format parsers where malformed input can lead to memory corruption. Organizations should implement layered defenses including email filtering, application whitelisting, and regular security updates to protect against exploitation of this type of vulnerability. The vulnerability also underscores the need for regular security assessments of third-party applications and the importance of keeping software updated to address known security flaws.