CVE-2006-6619 in Antihook
Summary
by MITRE
AVG Anti-Virus plus Firewall 7.5.431 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
CVE-2006-6619 represents a significant security vulnerability in AVG Anti-Virus Plus Firewall version 7.5.431 that stems from its reliance on the Windows Process Environment Block for process identification. The Process Environment Block serves as a critical data structure in Windows operating systems that contains essential information about a process, including its image path name, command line arguments, and window title. This vulnerability specifically exploits the software's trust in PEB data without proper validation, creating a pathway for local attackers to manipulate process identification mechanisms. The flaw resides in how AVG's security controls authenticate and monitor processes, as the application fails to implement robust verification measures that would prevent spoofing of critical PEB fields.
The technical exploitation of this vulnerability occurs through direct manipulation of the Process Environment Block structure in memory, allowing attackers to modify three specific fields that AVG uses for process identification. When an attacker spoofs the ImagePathName field, they can present a malicious process as a legitimate one by altering the path to the executable file. The CommandLine field manipulation enables attackers to disguise malicious command-line arguments as benign operations. Similarly, spoofing the WindowTitle field allows attackers to make their processes appear as legitimate user interface components. This three-pronged approach to PEB manipulation creates a comprehensive bypass mechanism that circumvents AVG's process monitoring and control capabilities. The vulnerability is classified under CWE-284, Access Control, as it represents a weakness in how the software enforces process access controls, and aligns with ATT&CK technique T1055 for Process Injection and T1068 for Exploitation for Privilege Escalation.
The operational impact of this vulnerability is severe for systems running the affected AVG version, as it allows local users to effectively bypass critical security controls that should prevent unauthorized process execution and monitoring. Attackers can leverage this vulnerability to execute malicious code while remaining undetected by AVG's process monitoring mechanisms, potentially leading to privilege escalation and persistent access. The vulnerability is particularly dangerous because it requires no elevated privileges to exploit, making it accessible to any local user with basic system access. This local privilege escalation vector can be combined with other techniques to establish a foothold in the system and potentially escalate privileges to administrator level. The impact extends beyond simple bypassing of security controls, as it undermines the fundamental trust model that security applications rely upon for protecting systems from malicious processes.
Mitigation strategies for CVE-2006-6619 should prioritize immediate software updates to the latest version of AVG Anti-Virus Plus Firewall that addresses this vulnerability through improved PEB validation mechanisms. Organizations should implement additional monitoring controls to detect potential PEB manipulation attempts and establish baseline process behaviors for comparison against suspicious activities. Security administrators should also consider implementing process integrity checks that verify the authenticity of process information beyond what is provided in the PEB structure. The vulnerability highlights the importance of not relying solely on Windows kernel data structures for security decisions, and emphasizes the need for robust input validation and authentication mechanisms in security software implementations. System hardening measures should include restricting local user privileges where possible and implementing additional layers of process monitoring that do not depend on potentially manipulable kernel structures. Additionally, regular security assessments should be conducted to identify other potential vulnerabilities in security applications that rely on similar trust models.