CVE-2007-4422 in Enterprise Firewall
Summary
by MITRE
The login interface in Symantec Enterprise Firewall 6.x, when a VPN with pre-shared key (PSK) authentication is enabled, generates different responses depending on whether or not a username is valid, which allows remote attackers to enumerate valid usernames.
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Analysis
by VulDB Data Team • 10/31/2017
The vulnerability identified as CVE-2007-4422 affects Symantec Enterprise Firewall version 6.x systems that utilize VPN with pre-shared key authentication mechanisms. This security flaw resides within the authentication interface design and creates a significant information disclosure risk that directly enables credential enumeration attacks. The vulnerability manifests when the system's login interface provides different response behaviors based on the validity of the username entered during authentication attempts, creating a side-channel information leak that adversaries can exploit to determine which usernames are legitimate within the system.
The technical implementation of this vulnerability stems from the inconsistent error handling within the authentication subsystem of the firewall software. When an attacker submits a login request, the system generates distinct response patterns whether the username exists in the system or not. This differential response behavior creates a predictable pattern that can be analyzed and reverse-engineered to identify valid user accounts. The flaw operates at the application layer and specifically impacts the authentication process rather than underlying network protocols, making it particularly dangerous as it targets the core security mechanism of the system. This type of vulnerability is categorized under CWE-200, which deals with information exposure, and represents a classic example of how poor error handling can lead to unauthorized information disclosure.
The operational impact of this vulnerability is substantial as it provides attackers with a straightforward method for conducting user enumeration attacks against the firewall system. Once valid usernames are identified, attackers can leverage this information for subsequent attacks including brute force attempts, password spraying, or social engineering campaigns. The vulnerability affects the confidentiality aspect of the CIA triad by exposing user account information that should remain protected. Attackers can systematically test usernames against the system and observe the different responses to identify valid accounts, effectively bypassing the need for direct credential guessing. This vulnerability particularly impacts organizations that rely on the firewall for network security and may have restricted access controls based on user authentication.
Mitigation strategies for this vulnerability involve implementing consistent error handling across all authentication interfaces to ensure that the system provides identical responses regardless of whether the username exists in the system. Organizations should configure their Symantec Enterprise Firewall systems to return generic error messages for all authentication attempts, preventing any information disclosure about user account validity. The implementation of account lockout mechanisms and rate limiting should be considered to prevent automated enumeration attempts, though these measures should not be the primary defense as they do not address the root cause. Additionally, organizations should consider upgrading to newer versions of Symantec Enterprise Firewall that have addressed this specific vulnerability, as the manufacturer has likely provided patches or updates to resolve the inconsistent response behavior. The vulnerability also highlights the importance of following secure coding practices and conducting thorough security reviews of authentication interfaces to prevent similar issues in other systems. This type of vulnerability is often mapped to ATT&CK technique T1078 which covers valid accounts and credential access, demonstrating how information disclosure can lead to broader compromise opportunities.