CVE-2006-1476 in Windows
Summary
by MITRE
Windows Firewall in Microsoft Windows XP SP2 produces incorrect application block alerts when the application filename is ".exe" (with no characters before the "."), which might allow local user-assisted users to trick a user into unblocking a Trojan horse program, as demonstrated by a malicious ".exe" program in a folder named "Internet Explorer," which triggers a question about whether to unblock the "Internet Explorer" program.
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Analysis
by VulDB Data Team • 09/05/2017
The vulnerability described in CVE-2006-1476 represents a significant security flaw in the Windows Firewall implementation within Microsoft Windows XP Service Pack 2. This issue stems from improper handling of application block alerts when encountering executable files with specific naming conventions. The flaw manifests when an application filename consists solely of ".exe" without any preceding characters, creating a condition where the firewall interface fails to properly identify the actual application being blocked. This misidentification creates a dangerous scenario where legitimate security warnings become misleading, potentially allowing attackers to exploit user trust and security awareness.
The technical root cause of this vulnerability lies in the Windows Firewall's application block alert mechanism which relies on filename parsing and display logic. When a program named ".exe" attempts to establish network connections, the firewall generates an alert that displays the parent directory name instead of the actual executable name. This occurs because the system's filename processing logic treats ".exe" as a special case that does not properly resolve to the intended application name, instead defaulting to the directory name where the file resides. The vulnerability specifically affects the user interface presentation of security warnings, creating a deceptive environment where users are presented with misleading information about the blocked application.
The operational impact of this vulnerability extends beyond simple user confusion to create a potential attack vector for social engineering campaigns. Attackers can exploit this flaw by placing malicious ".exe" files in directories with names that appear legitimate or trustworthy, such as "Internet Explorer" or "Windows Update." When the Windows Firewall blocks these programs, users receive alerts that reference the directory name rather than the actual malicious file, making it easier for attackers to convince users to bypass security protections. This technique leverages the psychological principle of familiarity and trust, as users are more likely to trust warnings that reference well-known system components or applications.
The security implications of this vulnerability align with several cybersecurity frameworks and threat modeling approaches. From a CWE perspective, this issue relates to CWE-170, which addresses improper handling of string termination or length, and CWE-20, which covers improper input validation. The vulnerability also maps to ATT&CK technique T1059.001, which involves executing malicious code through command-line interfaces, and T1566, which encompasses social engineering attacks. The attack scenario demonstrates how seemingly minor implementation flaws in security software can create significant risks when combined with user behavior patterns and social engineering tactics.
Mitigation strategies for this vulnerability should focus on both immediate system-level fixes and long-term security awareness improvements. Microsoft addressed this issue through security updates that corrected the filename parsing logic in Windows Firewall alert generation. Organizations should ensure all Windows XP systems are updated with the latest security patches and consider implementing additional security measures such as application whitelisting, enhanced user training programs, and network monitoring to detect suspicious activities. The vulnerability highlights the importance of proper input validation in security-critical applications and demonstrates why security software must maintain consistent and accurate user interface behavior to preserve user trust and security effectiveness.