CVE-2007-1535 in Windows
Summary
by MITRE
Microsoft Windows Vista establishes a Teredo address without user action upon connection to the Internet, contrary to documentation that Teredo is inactive without user action, which increases the attack surface and allows remote attackers to communicate via Teredo.
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Analysis
by VulDB Data Team • 09/14/2018
The vulnerability described in CVE-2007-1535 represents a significant deviation from Microsoft Windows Vista's documented network behavior regarding Teredo tunneling functionality. This issue manifests as an unintended automatic activation of Teredo addresses during internet connectivity establishment, directly contradicting the officially published documentation that specifies Teredo should remain inactive until user intervention. The fundamental problem lies in the operating system's failure to adhere to its own documented security policies, creating an unexpected network exposure that fundamentally alters the system's attack surface characteristics.
The technical flaw stems from the Windows Vista operating system's implementation of IPv6 transition mechanisms, specifically the Teredo tunneling protocol designed to facilitate IPv6 connectivity over IPv4 networks. Normally, Teredo should only activate when explicitly configured by a user or system administrator, serving as a bridge between IPv4 and IPv6 networks through a mechanism that encapsulates IPv6 packets within UDP/IPv4 datagrams. However, Vista's implementation incorrectly triggers Teredo activation automatically upon internet connection, bypassing the expected user consent and configuration processes that are fundamental to secure network operations.
This vulnerability significantly increases the attack surface by creating unintended network communication channels that remain hidden from normal security monitoring and user awareness. The automatic activation of Teredo addresses allows remote attackers to establish communication channels through the IPv6 tunneling mechanism without requiring explicit user action or system configuration. This behavior violates fundamental security principles of least privilege and explicit user consent, as network communication paths are established without user knowledge or authorization. The impact extends beyond simple network access, as Teredo tunnels can be leveraged for various malicious activities including reconnaissance, data exfiltration, and establishing persistent communication channels.
From a cybersecurity perspective, this vulnerability aligns with CWE-693, which addresses protection mechanism failures, and represents a clear violation of the principle of secure by default configurations. The issue directly enables techniques categorized under the ATT&CK framework's T1016 (System Network Configuration Discovery) and T1071.004 (Application Layer Protocol: DNS) where adversaries can exploit automatically configured network tunnels to maintain persistence and conduct network reconnaissance. The automatic activation of Teredo creates a backdoor-like functionality that adversaries can leverage to establish covert communication channels, making it particularly dangerous for enterprise environments where network monitoring and access controls are typically implemented.
The operational impact of this vulnerability extends beyond immediate security concerns to include compliance and risk management implications. Organizations relying on Windows Vista for network operations face increased risk of unauthorized access and data compromise due to the automatic network tunneling behavior. Security teams must now account for unexpected Teredo traffic in network monitoring systems, potentially leading to false positives or missed detection of actual threats. The vulnerability also impacts defense-in-depth strategies, as security controls designed around the assumption of manual Teredo configuration become ineffective. Mitigation strategies must include disabling Teredo tunneling through Group Policy settings, network segmentation to limit Teredo traffic, and enhanced monitoring for unexpected IPv6 tunneling activity. Additionally, system administrators should implement proper network access controls and firewall rules to restrict Teredo traffic, while ensuring that network monitoring tools are configured to detect and alert on unexpected Teredo tunneling behavior to maintain comprehensive security posture.