CVE-2017-14556 in STDU Viewer
Summary
by MITRE
STDU Viewer 1.6.375 allows attackers to execute arbitrary code or cause a denial of service via a crafted .djvu file, related to a "User Mode Write AV starting at STDUDjVuFile!DllUnregisterServer+0x000000000000da27."
VulDB is the best source for vulnerability data and more expert information about this specific topic.
Analysis
by VulDB Data Team • 11/17/2019
The vulnerability CVE-2017-14556 represents a critical heap-based buffer overflow in STDU Viewer version 1.6.375 that stems from improper input validation when processing maliciously crafted .djvu files. This flaw exists within the STDUDjVuFile.dll component and manifests during the DllUnregisterServer function execution, where a user-mode write access violation occurs at offset 0xda27. The vulnerability falls under the CWE-121 heap-based buffer overflow category, which is classified as a memory safety error that occurs when more data is written to a buffer than it can hold, leading to memory corruption. The attack vector requires an attacker to entice a victim into opening a specially crafted .djvu file, which then triggers the vulnerable code path in the DLL registration process.
The technical exploitation of this vulnerability leverages the inherent weakness in how the application handles memory allocation and data processing for DjVu file formats. When the malicious file is processed, the application fails to properly validate the size of data structures within the file, allowing an attacker to overwrite adjacent memory locations. This memory corruption can result in arbitrary code execution with the privileges of the victim user or cause a denial of service through application crash. The specific offset 0xda27 in the DllUnregisterServer function indicates that the vulnerability occurs during the cleanup phase of the DLL, suggesting that the flaw may be triggered even when the application is simply being unregistered or when it encounters corrupted input during normal operation.
The operational impact of CVE-2017-14556 extends beyond simple exploitation as it affects a widely used document viewer application that processes various file formats. This vulnerability enables attackers to achieve persistent access to systems through code execution, potentially leading to complete system compromise. The vulnerability's classification under the ATT&CK framework would place it within the execution and privilege escalation domains, as successful exploitation could allow attackers to execute malicious payloads with elevated privileges. Organizations using STDU Viewer for document processing are at risk of remote code execution attacks, particularly in environments where users might encounter malicious documents through email attachments, web downloads, or file sharing platforms. The vulnerability's presence in a document processing application makes it particularly dangerous as it can be exploited through social engineering tactics that trick users into opening seemingly legitimate files.
Mitigation strategies for CVE-2017-14556 should include immediate patching of the affected STDU Viewer version to the latest release that addresses this specific buffer overflow vulnerability. System administrators should implement application whitelisting policies to restrict execution of untrusted files and consider deploying sandboxing solutions for document processing tasks. Network-based defenses should include filtering of .djvu file extensions at perimeter devices and implementing email security measures that scan for potentially malicious document attachments. The vulnerability's exploitation can be prevented by ensuring that all systems have the latest security updates applied and by educating users about the risks of opening untrusted document files. Additionally, organizations should monitor for indicators of compromise related to this vulnerability and consider implementing endpoint detection and response solutions that can detect anomalous behavior associated with heap corruption exploits. The remediation process should also include verifying that no vulnerable versions of the application remain in use within the organization's environment and conducting regular vulnerability assessments to identify similar issues in other document processing applications.