CVE-2006-6620 in Antihook
Summary
by MITRE
Comodo Personal Firewall 2.3.6.81 relies on the Process Environment Block (PEB) to identify a process, which allows local users to bypass the product s controls on a process by spoofing the (1) ImagePathName, (2) CommandLine, and (3) WindowTitle fields in the PEB.
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Analysis
by VulDB Data Team • 08/10/2018
The vulnerability described in CVE-2006-6620 represents a critical security flaw in Comodo Personal Firewall version 2.3.6.81 that stems from its reliance on the Windows Process Environment Block for process identification. The Process Environment Block serves as a data structure within the Windows operating system that contains information about a process, including its executable path, command line arguments, and window title. This design decision creates a fundamental weakness in the firewall's ability to accurately verify process authenticity, as the PEB fields can be manipulated by malicious actors to deceive the security system.
The technical implementation of this vulnerability allows local attackers to exploit the firewall's trust in PEB data by selectively modifying three specific fields: ImagePathName, CommandLine, and WindowTitle. These fields are typically used by the firewall to establish process identity and enforce access controls. When an attacker spoofs these values, they can effectively mask the true nature of their malicious process, causing the firewall to incorrectly identify it as a legitimate application. This spoofing technique operates at the kernel level, where the firewall's monitoring mechanisms are unable to distinguish between the genuine process and the falsified representation.
The operational impact of this vulnerability is significant as it provides local users with a means to bypass the core protective mechanisms of the Comodo Personal Firewall. This creates a scenario where malicious software can execute with elevated privileges while remaining undetected by the firewall's access control policies. The vulnerability essentially undermines the fundamental security model of the application, allowing attackers to circumvent process-based filtering and potentially gain unauthorized access to system resources. This type of attack falls under the category of privilege escalation and application control bypass techniques that are commonly exploited in advanced persistent threat scenarios.
The security implications extend beyond simple bypass mechanisms and represent a failure in the firewall's identity verification process. This vulnerability aligns with CWE-284, which addresses improper access control, and demonstrates how reliance on potentially manipulable system structures can create security holes. From an ATT&CK framework perspective, this vulnerability maps to techniques involving process injection and privilege escalation, specifically targeting the execution and persistence phases of an attack lifecycle. The flaw essentially allows adversaries to perform malicious activities while appearing to be legitimate processes, making detection and incident response significantly more challenging. Organizations relying on this firewall version would be exposed to persistent threats that could evade traditional endpoint protection measures.
Mitigation strategies for this vulnerability require either immediate patching of the Comodo Personal Firewall software or implementation of additional security controls that do not rely solely on PEB data for process identification. System administrators should consider deploying complementary security solutions that utilize more robust process verification methods such as digital signatures, hash-based identification, or behavioral analysis. The vulnerability also highlights the importance of avoiding single points of failure in security implementations and emphasizes the need for layered defense mechanisms that can detect and prevent manipulation of system-level data structures. Organizations should conduct thorough security assessments to identify similar vulnerabilities in other security products that may rely on potentially manipulable system information for access control decisions.