CVE-2017-14570 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 a "User Mode Write AV near NULL starting at wow64!Wow64LdrpInitialize+0x00000000000008e1."
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Analysis
by VulDB Data Team • 11/17/2019
The vulnerability identified as CVE-2017-14570 affects STDU Viewer version 1.6.375, a document viewing application that processes XPS (XML Paper Specification) files. This critical security flaw represents a use-after-free condition that manifests as a user mode write access violation near NULL, specifically occurring at wow64!Wow64LdrpInitialize+0x00000000000008e1 within the Windows WoW64 subsystem. The vulnerability arises from inadequate input validation and memory management within the XPS file parsing component of the viewer application, creating a dangerous condition where attacker-controlled data can manipulate memory structures in ways that lead to arbitrary code execution or system instability.
The technical exploitation of this vulnerability occurs through the manipulation of specially crafted .xps files that contain malformed data structures. When the vulnerable STDU Viewer processes such malicious files, the application's XPS parser fails to properly validate memory allocations and deallocations, leading to a situation where freed memory locations are accessed or overwritten. This particular access violation occurs within the WoW64 compatibility layer, indicating that the vulnerability affects 32-bit applications running on 64-bit Windows systems, making it particularly dangerous in enterprise environments where mixed architecture systems are common. The specific location at wow64!Wow64LdrpInitialize suggests that the vulnerability may be related to how the Windows subsystem handles dynamic library loading and initialization for compatibility mode applications.
The operational impact of this vulnerability is severe and multifaceted, representing a high-risk threat that can result in complete system compromise or denial of service. Attackers can leverage this flaw to execute arbitrary code with the privileges of the affected user, potentially leading to full system takeover, data exfiltration, or persistent backdoor installation. The vulnerability's classification as a write access violation near NULL indicates that attackers can manipulate critical system memory locations, which aligns with common exploitation patterns described in the CWE database under CWE-476: NULL Pointer Dereference, though the specific context here involves a write operation rather than read. Additionally, the vulnerability can be exploited to cause denial of service, rendering the application unusable and potentially causing system crashes that impact legitimate users and business operations.
Organizations should implement immediate mitigation strategies including restricting user access to potentially malicious XPS files, deploying application whitelisting solutions to prevent execution of untrusted documents, and applying vendor patches as soon as they become available. The vulnerability demonstrates the importance of proper memory management practices and input validation in document processing applications, aligning with ATT&CK technique T1059.007 for Command and Scripting Interpreter and T1203 for Exploitation for Client Execution. System administrators should also consider implementing network-based intrusion detection systems to monitor for suspicious file handling patterns and ensure that all applications processing untrusted documents undergo rigorous security testing and code review processes to prevent similar vulnerabilities from being introduced in future versions.