CVE-2017-2270 in FileCapsule Deluxe Portable
Summary
by MITRE
Untrusted search path vulnerability in Encrypted files in self-decryption format created by FileCapsule Deluxe Portable Ver.2.0.9 and earlier allows an attacker to gain privileges via a Trojan horse DLL in an unspecified directory.
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Analysis
by VulDB Data Team • 10/26/2019
The vulnerability identified as CVE-2017-2270 represents a critical untrusted search path weakness affecting FileCapsule Deluxe Portable versions 2.0.9 and earlier. This flaw resides within the self-decryption functionality of encrypted files created by the software, creating a dangerous privilege escalation vector for malicious actors. The vulnerability stems from the application's improper handling of dynamic library loading during the decryption process, where the software fails to validate or restrict the directories from which it loads required DLL components.
The technical implementation of this vulnerability manifests through the application's reliance on a predictable search order for dynamic link libraries without proper sanitization of the search path. When FileCapsule processes encrypted files, it attempts to load necessary decryption modules from system directories, but due to insufficient path validation, an attacker can place a malicious Trojan horse DLL in a directory that gets searched before legitimate system locations. This behavior directly aligns with CWE-426 Untrusted Search Path, which describes how applications that search for libraries in untrusted locations can be exploited through DLL hijacking techniques. The vulnerability creates a scenario where any user with access to write permissions in the affected directories can potentially escalate privileges by substituting legitimate DLLs with malicious ones.
The operational impact of this vulnerability extends beyond simple privilege escalation to encompass broader system compromise possibilities. Attackers can leverage this weakness to execute arbitrary code with the privileges of the FileCapsule process, potentially leading to complete system takeover if the application runs with elevated permissions. The threat landscape for this vulnerability is particularly concerning because it operates silently without requiring user interaction, making it ideal for stealthy malware deployment. The vulnerability also demonstrates poor security practices in software development, specifically in how the application handles dynamic library loading and path resolution. According to ATT&CK framework, this vulnerability maps to T1055 Process Injection and T1546 Persistence, as the malicious DLL execution can be used to maintain persistence and inject code into legitimate processes.
Mitigation strategies for CVE-2017-2270 should focus on both immediate remediation and long-term architectural improvements. The most effective immediate solution involves upgrading to FileCapsule Deluxe Portable version 2.1.0 or later, where the developers have implemented proper DLL search path validation and secure library loading mechanisms. Organizations should also implement strict access controls on directories where FileCapsule operates, particularly restricting write permissions to prevent unauthorized DLL placement. Additionally, system administrators should employ application whitelisting solutions that prevent execution of unauthorized DLLs, and conduct regular security audits to identify potential search path vulnerabilities in other software applications. The vulnerability highlights the importance of following secure coding practices such as those outlined in the OWASP Secure Coding Practices, specifically regarding dynamic library loading and path validation. Network monitoring should also be enhanced to detect unusual DLL loading patterns that might indicate exploitation attempts, as this vulnerability can be leveraged in both local and remote attack scenarios.