CVE-2017-14553 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+0x00000000000085f5."
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Analysis
by VulDB Data Team • 11/17/2019
The vulnerability identified as CVE-2017-14553 affects STDU Viewer version 1.6.375, a document viewer application that processes various file formats including the DjVu format. This security flaw represents a critical remote code execution vulnerability that could be exploited by malicious actors to gain unauthorized access to systems running the affected software. The vulnerability manifests through improper handling of crafted DjVu files, specifically targeting the STDUDjVuFile.dll component within the application's architecture.
The technical root cause of this vulnerability lies in a user mode write access violation that occurs during the DllUnregisterServer function execution within the STDUDjVuFile.dll module. This type of flaw typically indicates that the application fails to properly validate input data when processing DjVu files, allowing attackers to manipulate memory structures through carefully constructed malicious files. The specific error location at STDUDjVuFile!DllUnregisterServer+0x00000000000085f5 suggests that the vulnerability occurs during the DLL unregistering process, which is often invoked when the application handles file operations or when components are unloaded from memory. This particular memory access violation falls under the category of heap-based buffer overflows or memory corruption issues that are commonly classified under CWE-121, heap-based buffer overflow, or more specifically CWE-787, out-of-bounds write.
The operational impact of this vulnerability is severe and multifaceted, as it provides attackers with the capability to execute arbitrary code with the privileges of the affected application. When a user opens a maliciously crafted DjVu file, the vulnerability can be triggered, potentially allowing remote code execution attacks that could lead to complete system compromise. The vulnerability also enables denial of service conditions, where the application may crash or become unresponsive, disrupting legitimate user operations and potentially creating availability issues for critical systems. This type of vulnerability aligns with ATT&CK technique T1059.007 for command and scripting interpreter, as successful exploitation could enable attackers to execute commands on the compromised system.
The exploitation of this vulnerability typically involves crafting a specially formatted DjVu file that contains malicious data structures designed to trigger the memory corruption during file processing. Attackers could potentially deliver these malicious files through various attack vectors including email attachments, web downloads, or compromised websites. The vulnerability affects systems running STDU Viewer 1.6.375 and potentially other versions within the same software family that share similar processing mechanisms for DjVu files. Organizations should consider this vulnerability in their threat modeling and incident response planning, particularly in environments where users may encounter untrusted DjVu files from external sources.
Mitigation strategies for this vulnerability should include immediate patching of the affected software to the latest version that addresses the memory handling issues within the DjVu file processing module. System administrators should implement application whitelisting policies to restrict execution of unauthorized applications and consider deploying sandboxing mechanisms for document processing. Network-level defenses such as content filtering and email security solutions can help prevent the delivery of malicious DjVu files. Additionally, users should be educated about the risks of opening untrusted files and the importance of keeping software updated. The vulnerability also highlights the importance of secure coding practices and thorough input validation, particularly when dealing with complex file format parsers that must handle untrusted input data from external sources.