CVE-2017-14558 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+0x0000000000018cc2."
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 identified as CVE-2017-14558 affects STDU Viewer version 1.6.375, a document viewing application that processes djvu files. This weakness represents a critical security flaw that could enable remote code execution or denial of service attacks through maliciously crafted djvu file inputs. The vulnerability manifests during the processing of specially constructed .djvu files, which triggers an abnormal execution path within the application's file handling mechanisms.
The technical root cause of this vulnerability stems from a user mode write access violation occurring at the address STDUDjVuFile!DllUnregisterServer+0x0000000000018cc2 within the application's dynamic link library. This type of memory access violation typically indicates that the application attempts to write to a memory location that it does not have permission to access or that has already been freed. The specific address location suggests that the error occurs during the DLL unregistering process, which is part of the application's file processing lifecycle when handling djvu format files. This memory corruption vulnerability falls under the CWE-121 category of "Stack-based Buffer Overflow" or potentially CWE-787 "Out-of-bounds Write" depending on the exact implementation details.
The operational impact of this vulnerability is significant as it allows attackers to execute arbitrary code on vulnerable systems with the privileges of the user running STDU Viewer. This could lead to complete system compromise, data exfiltration, or persistent backdoor installation. The vulnerability is particularly dangerous because it can be exploited through social engineering tactics where users are tricked into opening maliciously crafted djvu files, making it a common attack vector in phishing campaigns or targeted attacks. The denial of service aspect means that even if code execution is not achieved, attackers can still disrupt legitimate use of the application by causing crashes or system instability.
Mitigation strategies for this vulnerability should focus on immediate patching of the STDU Viewer application to the latest version that contains the fix for this memory corruption issue. Organizations should implement strict file validation policies that prevent users from opening untrusted djvu files, particularly those received through email attachments or downloaded from untrusted sources. Network-based protections such as web application firewalls and content filtering systems can help block malicious djvu files before they reach end users. Additionally, system administrators should consider implementing application whitelisting policies that only allow execution of known good versions of STDU Viewer and disable the processing of potentially malicious file formats. From an ATT&CK framework perspective, this vulnerability maps to T1203 "Exploitation for Client Execution" and T1059 "Command and Scripting Interpreter" as attackers would leverage this flaw to execute malicious code and potentially escalate privileges within the compromised system environment.