CVE-2017-2130 in Client Internet Explorer
Summary
by MITRE
Untrusted search path vulnerability in the installer of PhishWall Client Internet Explorer version Ver. 3.7.13 and earlier allows remote attackers to gain privileges via a Trojan horse DLL in an unspecified directory.
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Analysis
by VulDB Data Team • 09/22/2020
The vulnerability identified as CVE-2017-2130 represents a critical untrusted search path weakness within the PhishWall Client Internet Explorer component version 3.7.13 and earlier. This flaw exists in the installer mechanism that governs how the software handles dynamic link library loading processes during installation. The vulnerability stems from the application's failure to properly validate or sanitize the search paths used when loading DLL modules, creating an exploitable condition that adversaries can leverage for privilege escalation.
The technical implementation of this vulnerability aligns with CWE-428, which specifically addresses untrusted search path conditions where software applications search for libraries in insecure locations. In this case, the installer process does not enforce strict path validation when resolving DLL dependencies, allowing attackers to place malicious Trojan horse DLL files in directories that are searched before legitimate system locations. The attacker can exploit this by placing a crafted malicious DLL in a directory that the installer will prioritize during the loading sequence, effectively hijacking the execution flow.
From an operational perspective, this vulnerability presents a significant risk to organizations deploying PhishWall Client software, as it enables remote code execution with elevated privileges. The attack vector requires minimal user interaction since the malicious DLL is loaded automatically during the installation process, making it particularly dangerous in enterprise environments where such installations may occur with administrative privileges. The vulnerability can be exploited across different operating system versions and architectures, amplifying its potential impact.
The ATT&CK framework categorizes this vulnerability under privilege escalation techniques, specifically leveraging the "Dynamic Link Library (DLL) Hijacking" tactic. This method allows adversaries to execute arbitrary code with the privileges of the victim process, typically resulting in system compromise. The vulnerability's exploitation requires the attacker to have access to the target system's file system to place the malicious DLL in an appropriate location, but no special privileges are needed for the initial installation process itself.
Mitigation strategies should focus on immediate patching of affected software versions and implementing strict directory permissions to prevent unauthorized DLL placement. Organizations should also consider implementing application whitelisting policies that restrict which DLLs can be loaded during installation processes. Additionally, security configurations should enforce secure search paths by modifying the PATH environment variable to prioritize system directories over user or application-specific locations, ensuring that legitimate system libraries are loaded before any potentially compromised modules. Regular security assessments and monitoring of installation directories can help detect unauthorized DLL placement attempts, while network segmentation can limit the potential impact of successful exploitation attempts.