CVE-2017-14567 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 .xps file, related to an "Illegal Instruction Violation starting at Unknown Symbol @ 0x00000000028c024d called from STDUXPSFile!DllUnregisterServer+0x000000000002e77b."
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Analysis
by VulDB Data Team • 11/17/2019
The vulnerability CVE-2017-14567 affects STDU Viewer version 1.6.375, a document viewing application that processes XPS (XML Paper Specification) files. This critical security flaw represents a buffer overflow condition that can be exploited through maliciously crafted XPS documents, potentially allowing remote code execution or system denial of service. The vulnerability manifests as an illegal instruction violation within the application's processing of XPS files, specifically occurring at memory address 0x00000000028c024d during the DllUnregisterServer function execution. The attack vector involves an attacker crafting a specially formatted .xps file that, when opened by the vulnerable STDU Viewer application, triggers the exploitable condition. This type of vulnerability falls under the CWE-121 category of stack-based buffer overflow, where insufficient bounds checking allows an attacker to overwrite adjacent memory locations and potentially execute arbitrary code.
The technical exploitation of this vulnerability occurs through memory corruption that happens during the XPS file parsing process, particularly when the application attempts to unregister its dynamic link library components. The error message indicates that the illegal instruction occurs within the STDUXPSFile module, specifically within the DllUnregisterServer function which is responsible for cleaning up COM registration information. When an attacker supplies a malformed XPS file, the application's parser fails to properly validate input data, leading to a situation where execution flows into an invalid memory address, causing either a crash or potential code execution. This behavior aligns with the ATT&CK technique T1203 - Exploitation for Client Execution, where adversaries leverage application vulnerabilities to execute malicious code on target systems. The vulnerability is particularly dangerous because it can be triggered simply by opening a malicious file, requiring no user interaction beyond the initial file access, making it a prime candidate for social engineering attacks.
The operational impact of this vulnerability extends beyond simple denial of service scenarios, as successful exploitation could provide attackers with complete system compromise. An attacker who successfully exploits this vulnerability could execute arbitrary code with the privileges of the STDU Viewer process, potentially allowing for privilege escalation, data exfiltration, or installation of additional malware. The vulnerability affects any system running STDU Viewer 1.6.375 or earlier versions, making it a widespread concern for organizations that have not updated their document viewing applications. The vulnerability's severity is compounded by the fact that XPS files are commonly used for distributing documents, making them a likely vector for targeted attacks. Organizations that have not patched this vulnerability remain at risk of exploitation through phishing campaigns, malicious file sharing, or other attack vectors that deliver crafted XPS files to unsuspecting users. The vulnerability demonstrates poor input validation practices in the application's file processing pipeline and highlights the importance of implementing robust memory safety mechanisms in document processing applications.
Mitigation strategies for this vulnerability include immediate patching of STDU Viewer to version 1.6.376 or later, which contains the necessary fixes for the buffer overflow condition. System administrators should also implement file type restrictions, particularly for XPS files, through group policies or application whitelisting solutions that prevent execution of potentially malicious files. Network-based protections such as email filtering and web proxies can help block malicious XPS files before they reach end-user systems. Additionally, users should be educated about the risks of opening untrusted documents and encouraged to verify file sources before opening them. The vulnerability serves as a reminder of the importance of keeping document processing applications updated and following secure coding practices that prevent buffer overflows and other memory corruption vulnerabilities. Organizations should also consider implementing sandboxing techniques for document viewing applications to isolate potential exploits and limit their impact on the broader system infrastructure.