CVE-2017-8781 in XnView Classic
Summary
by MITRE
XnView Classic for Windows Version 2.40 allows user-assisted remote attackers to execute code via a crafted JPEG 2000 file that is mishandled during the opening of a directory in "Browser" mode, because of a "Stack Buffer Overrun" issue.
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Analysis
by VulDB Data Team • 10/22/2019
The vulnerability identified as CVE-2017-8781 represents a critical stack buffer overrun flaw in XnView Classic for Windows version 2.40 that enables remote code execution through crafted malicious JPEG 2000 files. This vulnerability exists within the application's directory browsing functionality when processing specially crafted image files, creating a dangerous attack vector that can be exploited by remote adversaries with minimal user interaction. The flaw specifically manifests when the application attempts to open directories in Browser mode, where it fails to properly validate or handle the metadata contained within malicious JPEG 2000 files, leading to memory corruption that can be leveraged for arbitrary code execution.
The technical root cause of this vulnerability aligns with CWE-121, which describes stack-based buffer overflow conditions where insufficient bounds checking allows attackers to overwrite adjacent memory locations on the stack. When XnView Classic processes a malicious JPEG 2000 file, the application's image parsing routines fail to properly validate the size and structure of the file's metadata, particularly in the way it handles the JP2 (JPEG 2000) header information. This inadequate input validation creates an exploitable condition where attacker-controlled data can overflow the allocated stack buffer, potentially overwriting return addresses and other critical stack memory locations that control program execution flow.
From an operational perspective, this vulnerability presents a significant risk to users who may inadvertently encounter malicious JPEG 2000 files while browsing directories or opening image collections. The user-assisted nature of the attack means that exploitation requires some level of user interaction, typically through opening a directory containing the malicious file, but this interaction can be minimized through social engineering or automated file delivery mechanisms. Attackers can leverage this vulnerability to execute arbitrary code with the privileges of the affected user, potentially leading to full system compromise, data exfiltration, or lateral movement within network environments.
The impact of CVE-2017-8781 aligns with ATT&CK technique T1059.007 for command and scripting interpreter, as successful exploitation could enable attackers to execute malicious payloads through the compromised application. Security professionals should consider this vulnerability as part of broader exploitation chains where initial access might be gained through other vectors, but the vulnerability provides a reliable method for privilege escalation and persistent access. The vulnerability affects not only individual users but also organizations that rely on XnView Classic for image management, particularly in environments where users may encounter untrusted image files from external sources or web applications.
Organizations should implement immediate mitigations including updating to patched versions of XnView Classic, implementing application whitelisting policies to restrict execution of vulnerable applications, and deploying network-based intrusion detection systems to monitor for exploitation attempts. Additionally, users should be educated about the risks of opening image files from untrusted sources and the importance of keeping software updated. The vulnerability demonstrates the critical importance of proper input validation and memory management in multimedia processing applications, highlighting how seemingly benign file format handling can create dangerous security exposures that can be exploited for remote code execution.