CVE-2007-0081 in Personal Firewall
Summary
by MITRE
Sunbelt Kerio Personal Firewall (SKPF) 4.3.268 and 4.3.246, and possibly other versions allows local users to provide a Trojan horse iphlpapi.dll to SKPF by placing it in the installation directory.
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Analysis
by VulDB Data Team • 09/28/2017
The vulnerability identified as CVE-2007-0081 represents a critical privilege escalation flaw in Sunbelt Kerio Personal Firewall versions 4.3.268 and 4.3.246, as well as potentially other versions within the same release line. This issue stems from the firewall application's insecure handling of dynamic link library (dll) loading mechanisms during its operation. The vulnerability occurs when the Kerio Personal Firewall application loads the iphlpapi.dll library from its installation directory without proper validation of the library's authenticity or integrity. This behavior creates an exploitable condition where a local attacker can place a malicious version of iphlpapi.dll in the application's installation directory, effectively replacing the legitimate system library with a Trojan horse implementation that can execute arbitrary code with the privileges of the running firewall process.
The technical flaw manifests through the application's reliance on the Windows dynamic loading mechanism which searches for required libraries in the application's directory before checking system directories. This approach, while common in legacy applications, creates a dangerous attack surface when the application runs with elevated privileges. When the Kerio Personal Firewall attempts to load the iphlpapi.dll library, it will first locate and load the malicious version placed by the attacker in the installation directory, rather than the legitimate system library. This dll hijacking technique allows attackers to inject malicious code into the firewall process, potentially gaining unauthorized access to the system or compromising the firewall's protective capabilities.
The operational impact of this vulnerability extends beyond simple privilege escalation, as it directly compromises the security posture of systems protected by the affected firewall. A local attacker with basic user privileges can exploit this vulnerability to gain elevated system access, potentially enabling further attacks such as lateral movement, data exfiltration, or complete system compromise. The vulnerability affects systems where Kerio Personal Firewall is installed and running with administrative privileges, creating a persistent threat vector that could remain undetected for extended periods. The attack requires only local access to the system, making it particularly dangerous in environments where physical access is possible or where attackers have already gained initial footholds through other means. This flaw undermines the fundamental security assumptions of the firewall application, as it allows an attacker to bypass the very protection mechanisms the software is designed to provide.
Mitigation strategies for CVE-2007-0081 should focus on immediate remediation and long-term architectural improvements. The most effective immediate solution involves applying the vendor's security patches or upgrading to a version that properly validates library loading or implements secure library resolution mechanisms. Organizations should also implement strict file permissions on the Kerio Personal Firewall installation directory to prevent unauthorized modifications, particularly ensuring that only authorized administrators can write to these locations. Additionally, system administrators should consider implementing application whitelisting policies that restrict which dll files can be loaded by the Kerio Personal Firewall process. From a defensive perspective, monitoring for unauthorized file modifications in the application installation directory and implementing file integrity monitoring solutions can help detect exploitation attempts. This vulnerability aligns with CWE-427 Uncontrolled Search Path Element and CWE-428 Uncontrolled Search Path Element, both of which address insecure library loading practices. The attack pattern corresponds to ATT&CK technique T1055.001 Process Injection: Dynamic-link Library Injection, as it involves injecting malicious code through legitimate system libraries. Organizations should also consider the broader implications of this vulnerability in relation to defense-in-depth strategies and ensure that multiple layers of security controls are in place to prevent similar issues from compromising their security infrastructure.