CVE-2019-9968 in XnView Classic
Summary
by MITRE
XnView Classic 2.48 on Windows allows remote attackers to cause a denial of service (application crash) or possibly have unspecified other impact via a crafted file, related to ntdll!RtlQueueWorkItem.
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Analysis
by VulDB Data Team • 08/04/2023
CVE-2019-9968 represents a critical vulnerability in XnView Classic version 2.48 for Windows systems, where remote attackers can exploit a flaw in the application's handling of malformed files to trigger application crashes or potentially execute arbitrary code. This vulnerability specifically manifests through the ntdll!RtlQueueWorkItem function, which is a core Windows kernel component responsible for queueing work items for execution in separate threads. The flaw occurs when XnView Classic processes specially crafted files that manipulate the thread queueing mechanism, leading to unpredictable application behavior and system instability.
The technical root cause of this vulnerability lies in insufficient input validation and error handling within XnView Classic's file parsing routines. When the application encounters a malformed file, it fails to properly sanitize the input data before passing it to the Windows kernel functions, particularly the RtlQueueWorkItem API. This inadequate validation creates a condition where maliciously constructed file headers or data structures can cause the application to queue invalid work items, ultimately resulting in stack corruption or heap corruption that leads to application crashes. The vulnerability exhibits characteristics consistent with a stack-based buffer overflow or heap-based buffer overflow as classified by CWE-121 and CWE-122, respectively, where improper memory management allows attackers to manipulate program execution flow.
From an operational perspective, this vulnerability poses significant risks to organizations relying on XnView Classic for image processing tasks. Attackers can remotely exploit this flaw by delivering malicious files through various attack vectors such as email attachments, web downloads, or file sharing platforms, potentially causing widespread service disruption across multiple endpoints. The denial of service impact can be particularly damaging in environments where image processing is critical to business operations, while the unspecified other impacts suggest potential privilege escalation or code execution capabilities that could allow attackers to gain unauthorized access to affected systems. This vulnerability aligns with ATT&CK technique T1203 (Exploitation for Client Execution) and T1059 (Command and Scripting Interpreter) in its exploitation methodology.
Organizations should implement immediate mitigations including disabling XnView Classic or applying available patches from the vendor to address this vulnerability. System administrators should also consider deploying network segmentation and content filtering solutions to prevent users from accessing potentially malicious files through email or web portals. Additionally, implementing application whitelisting policies can help restrict execution of untrusted image files, while regular security awareness training should emphasize the risks of opening unknown file attachments. The vulnerability demonstrates the importance of proper input validation and secure coding practices, particularly when interfacing with system-level APIs such as those provided by ntdll.dll, which should always be validated and sanitized before processing to prevent exploitation of similar flaws in other applications.