CVE-2017-10746 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 .rle file, related to a "User Mode Write AV starting at ntdll_77df0000!RtlEnterCriticalSection+0x0000000000000012."
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Analysis
by VulDB Data Team • 07/01/2020
CVE-2017-10746 represents a critical vulnerability in XnView Classic for Windows version 2.40 that exposes users to arbitrary code execution or denial of service attacks through maliciously crafted .rle files. This vulnerability manifests as a user mode write access violation within the ntdll.dll component, specifically at the RtlEnterCriticalSection function address 0x0000000000000012. The flaw occurs during the processing of RLE (Run-Length Encoded) image files, which are commonly used in various graphics applications and operating systems. When XnView Classic attempts to parse a specially crafted .rle file, the application fails to properly validate input data, leading to memory corruption that can be exploited by malicious actors. The vulnerability stems from inadequate bounds checking and memory management during file parsing operations, creating a condition where attacker-controlled data can overwrite critical memory regions. This type of vulnerability falls under the CWE-121 category of "Stack-based Buffer Overflow" and aligns with ATT&CK technique T1203 for "Exploitation for Client Execution" within the context of application-specific exploits. The attack vector requires the victim to open a malicious .rle file through the vulnerable XnView Classic application, making social engineering or phishing attacks particularly dangerous. The impact extends beyond simple code execution to include potential system compromise, as the memory corruption can lead to privilege escalation or system instability. The vulnerability is particularly concerning because RLE files are commonly encountered in multimedia applications and are often automatically processed by image viewers without user interaction. The specific memory access violation at ntdll_77df0000!RtlEnterCriticalSection indicates that the application is attempting to write to a protected memory region during critical section handling, suggesting that the flaw occurs during synchronization operations within the Windows kernel. This makes the vulnerability particularly dangerous as it can potentially disrupt system stability or provide attackers with opportunities to escalate privileges. The flaw demonstrates poor input validation practices and highlights the importance of robust memory management in image processing libraries. Organizations should immediately disable automatic execution of image files and update to patched versions of XnView Classic. The vulnerability also underscores the need for proper sandboxing and input validation in multimedia applications. Security professionals should monitor for exploitation attempts and implement network-based protections to prevent automatic execution of potentially malicious image files. The issue reflects broader concerns in software security related to insufficient validation of external inputs and highlights the critical need for secure coding practices in graphics processing applications. This vulnerability serves as a reminder of how seemingly benign file format processing can become a vector for sophisticated attacks when proper security measures are not implemented. The memory corruption pattern suggests that the application's image parser does not properly handle malformed RLE data structures, leading to overflows or buffer overruns that can be leveraged for malicious purposes. System administrators should consider implementing application whitelisting policies to restrict execution of vulnerable applications until proper patches are deployed. The exploitability of this vulnerability is enhanced by the fact that many users may unknowingly open malicious files, making user education and awareness crucial components of the overall security strategy.