CVE-2017-2247 in Lhaz
Summary
by MITRE
Untrusted search path vulnerability in Self-extracting archive files created by Lhaz version 2.4.0 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-2017-2247 represents a critical untrusted search path weakness within Lhaz version 2.4.0 and earlier implementations. This flaw manifests specifically in self-extracting archive files generated by the software, creating a dangerous privilege escalation vector that attackers can exploit through carefully crafted malicious components. The vulnerability stems from the application's failure to properly validate and sanitize the search paths used during the extraction process, allowing malicious actors to place Trojan horse DLL files in directories that are inadvertently searched by the vulnerable application.
The technical exploitation of this vulnerability occurs through a classic DLL hijacking attack pattern where the malicious DLL is placed in a location that gets searched before legitimate system directories. When the self-extracting archive executes and attempts to load required libraries, it inadvertently loads the attacker-controlled DLL instead of the intended legitimate components. This behavior aligns with CWE-427 Uncontrolled Search Path Elements, which specifically addresses the issue of applications searching directories in an uncontrolled manner. The vulnerability essentially creates a situation where the application's trust model is compromised, as it cannot distinguish between legitimate and malicious components within its search path.
The operational impact of this vulnerability extends beyond simple privilege escalation to encompass potential full system compromise when the vulnerable application runs with elevated privileges. Attackers can leverage this weakness to execute arbitrary code with the privileges of the target user, potentially leading to persistent access, data exfiltration, or further network infiltration. The attack vector is particularly concerning because it requires minimal user interaction beyond executing a self-extracting archive, making it an attractive target for social engineering campaigns. This vulnerability directly maps to ATT&CK technique T1059 Command and Scripting Interpreter and T1068 Exploitation for Privilege Escalation, as it provides a mechanism for executing malicious code and elevating privileges through trusted application execution paths.
Mitigation strategies for CVE-2017-2247 should focus on both immediate remediation and long-term architectural improvements. The most effective immediate solution involves updating to Lhaz version 2.4.1 or later, which contains the necessary patches to address the untrusted search path vulnerability. Organizations should also implement strict directory permissions and ensure that the application's search paths are properly constrained to prevent loading of unexpected DLLs. Additionally, system administrators should monitor for suspicious DLL placements in common search directories and implement application whitelisting policies to prevent execution of unauthorized code. The vulnerability highlights the importance of secure coding practices and proper input validation, particularly when dealing with file operations and library loading mechanisms. Organizations should also consider implementing security awareness training to prevent users from executing untrusted self-extracting archives, as the attack chain often relies on user execution of malicious files.