CVE-2017-9904 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 controls Branch Selection starting at ntdll_77df0000!RtlpLowFragHeapFree+0x000000000000001f."
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Analysis
by VulDB Data Team • 10/23/2019
The vulnerability identified as CVE-2017-9904 affects XnView Classic for Windows version 2.40 and represents a critical remote code execution and denial of service flaw. This issue stems from improper handling of maliciously crafted .fpx files within the image processing library, specifically within the ntdll component of the Windows operating system. The vulnerability manifests when the application attempts to process a malformed .fpx file, leading to unpredictable behavior that can result in system instability or complete system crashes.
The technical root cause of this vulnerability lies in the improper validation of input data within the XnView Classic image processing pipeline. When the application encounters a specially crafted .fpx file, it triggers a fault in the Windows ntdll library at the address ntdll_77df0000!RtlpLowFragHeapFree+0x000000000000001f. This memory management function becomes compromised when processing malformed heap data, causing the application to execute unexpected code paths or corrupt memory structures. The flaw demonstrates characteristics of a heap-based buffer overflow or memory corruption vulnerability, where attacker-controlled data influences the program's execution flow.
The operational impact of this vulnerability extends beyond simple denial of service scenarios, as it potentially enables remote attackers to execute arbitrary code on affected systems. The unspecified other impacts mentioned in the CVE description suggest that attackers may be able to leverage this vulnerability for privilege escalation or information disclosure. Since XnView Classic is commonly used for image viewing and management, attackers could exploit this vulnerability through malicious email attachments, web downloads, or file sharing scenarios where users open the crafted .fpx files. The vulnerability affects systems running Windows operating systems and represents a significant risk to both individual users and enterprise environments that rely on image viewing applications.
This vulnerability aligns with CWE-125, which describes out-of-bounds read conditions, and CWE-787, which covers out-of-bounds write conditions, both of which are common in heap-based memory corruption scenarios. The attack surface maps to several MITRE ATT&CK techniques including T1203, Exploitation for Client Execution, and T1059, Command and Scripting Interpreter, as the vulnerability could enable attackers to execute malicious code remotely. Organizations should prioritize immediate patching of affected systems and implement network segmentation controls to limit exposure. Additional mitigations include disabling automatic image preview features, implementing strict file type validation, and deploying network-based intrusion detection systems to monitor for exploitation attempts targeting this specific vulnerability.
The vulnerability demonstrates the critical importance of proper input validation in multimedia processing applications and highlights the risks associated with legacy software that may not receive regular security updates. System administrators should conduct comprehensive vulnerability assessments to identify all instances of XnView Classic installations and ensure timely deployment of vendor-provided patches or upgrades to mitigate this and similar vulnerabilities.