CVE-2015-8264 in Online Scanner
Summary
by MITRE
Untrusted search path vulnerability in F-Secure Online Scanner allows remote attackers to execute arbitrary code and conduct DLL hijacking attacks via a Trojan horse DLL that is located in the same folder as F-SecureOnlineScanner.exe.
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Analysis
by VulDB Data Team • 11/03/2019
The vulnerability identified as CVE-2015-8264 represents a critical untrusted search path issue within the F-Secure Online Scanner application that creates significant security risks for endpoint systems. This flaw exists in the application's dynamic link library loading mechanism where the software fails to properly validate or restrict the directories from which it loads dynamic libraries. The vulnerability specifically affects the F-SecureOnlineScanner.exe executable which, when executed, searches for required DLL files in the same directory where the executable resides, creating an exploitable condition that adversaries can leverage for malicious purposes. According to CWE-427, this vulnerability falls under the category of uncontrolled search path elements, a well-documented weakness that has been consistently exploited in various security breaches across different software platforms. The issue stems from the application's failure to implement proper security measures such as explicit library paths or secure loading mechanisms that would prevent loading of unauthorized DLL files from potentially compromised directories.
The operational impact of this vulnerability extends beyond simple code execution capabilities to encompass full system compromise through DLL hijacking techniques. Attackers can place a malicious Trojan horse DLL file in the same directory as the F-SecureOnlineScanner.exe executable, causing the legitimate application to load and execute the malicious code with the privileges of the user running the scanner. This creates a persistent threat vector where malware can remain undetected while gaining elevated system access, potentially leading to data exfiltration, system reconnaissance, or further lateral movement within the network. The vulnerability is particularly concerning because it operates at the application level and can be exploited without requiring administrative privileges or specific system knowledge from the attacker. From an ATT&CK framework perspective, this vulnerability maps directly to techniques such as T1059.001 for execution through command and scripting interpreters and T1574.001 for hijacking execution flow through dynamic link library loading. The exploitation process typically involves placing a specially crafted DLL file with the same name as a legitimate dependency, allowing the application to inadvertently execute malicious code during normal operation.
Mitigation strategies for CVE-2015-8264 require both immediate remediation and long-term security hardening approaches to address the root cause of the untrusted search path vulnerability. Organizations should immediately apply the vendor-provided security patches released by F-Secure to resolve the underlying issue in the application's library loading mechanism. Additionally, system administrators should implement proper file system permissions to restrict write access to directories containing critical executables and their associated DLL dependencies, ensuring that only authorized personnel can modify these locations. Network segmentation and application whitelisting policies can further reduce the attack surface by preventing unauthorized DLL files from being placed in vulnerable directories. Security monitoring should be enhanced to detect unusual file creation patterns in directories containing executable files, particularly those with high-privilege access requirements. The implementation of secure coding practices including explicit DLL loading paths, use of SafeDllSearchMode, and proper application sandboxing can prevent similar vulnerabilities from occurring in other software applications. Organizations should also consider implementing behavioral analysis tools that can detect anomalous execution patterns indicative of DLL hijacking attempts, providing an additional layer of defense against this class of vulnerability that has been consistently exploited across multiple vendors and applications.