CVE-2017-14271 in XnView Classic
Summary
by MITRE
XnView Classic for Windows Version 2.40 allows attackers to execute arbitrary code or cause a denial of service via a crafted .jb2 file, related to a "User Mode Write AV starting at ntdll_77400000!RtlImpersonateSelfEx+0x000000000000024e."
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Analysis
by VulDB Data Team • 11/14/2019
CVE-2017-14271 represents a critical vulnerability in XnView Classic for Windows version 2.40 that enables remote code execution and denial of service attacks through maliciously crafted .jb2 files. This vulnerability manifests as a user mode write access violation within the ntdll.dll module, specifically at the RtlImpersonateSelfEx+0x000000000000024e offset. The flaw occurs during the processing of JPEG 2000 image files with the .jb2 extension, where the application fails to properly validate input data before attempting to write to memory locations. This type of vulnerability falls under the Common Weakness Enumeration category CWE-121, which deals with stack-based buffer overflow conditions, though the specific manifestation here involves heap corruption through improper memory management during file parsing operations.
The technical exploitation of this vulnerability leverages a classic buffer over-read scenario where the XnView application attempts to process malformed .jb2 file structures that trigger memory corruption in the Windows kernel. When the application parses the crafted file, it encounters unexpected data sequences that cause the memory management subsystem to attempt writing to unauthorized memory regions, resulting in an access violation that can be exploited to execute arbitrary code or force application termination. The vulnerability specifically targets the Windows NT kernel's impersonation functionality, suggesting that attackers could potentially escalate privileges by leveraging the compromised execution context. This aligns with ATT&CK technique T1068, which covers 'Local Privilege Escalation' through exploitation of kernel vulnerabilities.
From an operational perspective, this vulnerability presents a significant risk to organizations relying on XnView Classic for image processing tasks, particularly in environments where users may encounter untrusted image files from external sources. The impact extends beyond simple denial of service to potential system compromise, as successful exploitation could allow attackers to execute malicious code with the privileges of the affected user account. The vulnerability affects Windows systems running XnView Classic 2.40 and earlier versions, making it particularly dangerous in corporate environments where image viewing applications are commonly used for document review and file sharing. The attack vector requires only that a user open or preview the malicious .jb2 file, making social engineering attacks more effective. Organizations should note that this vulnerability demonstrates the importance of input validation and proper memory management in multimedia processing applications, as image viewers are frequently targeted due to their broad usage and the nature of image file formats which can contain complex metadata structures.
Mitigation strategies for CVE-2017-14271 should prioritize immediate patching of XnView Classic to version 2.41 or later, which contains fixes for the memory corruption issues. System administrators should implement file extension filtering to prevent automatic execution of .jb2 files, particularly in environments where untrusted content may be encountered. Network-based protections can include implementing content filtering rules that block .jb2 file transfers or require additional validation before allowing such files to be processed. Additionally, users should be educated about the risks of opening untrusted image files and the importance of keeping software updated. Organizations may also consider implementing sandboxing techniques for image viewing operations or using alternative image processing tools that have undergone more rigorous security testing. The vulnerability highlights the necessity of regular security assessments for multimedia applications, as these tools often receive less security scrutiny than core system components but can provide valuable attack vectors for adversaries.