CVE-2011-3444 in Mac OS X
Summary
by MITRE
Address Book in Apple Mac OS X before 10.7.3 automatically switches to unencrypted sessions upon failure of encrypted connections, which allows remote attackers to read CardDAV data by terminating an encrypted connection and then sniffing the network.
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Analysis
by VulDB Data Team • 11/29/2021
The vulnerability described in CVE-2011-3444 represents a critical security flaw in Apple Mac OS X versions prior to 10.7.3, specifically within the Address Book application's handling of CardDAV protocol connections. This issue stems from a flawed fallback mechanism that automatically transitions the application from encrypted to unencrypted communication when encrypted connections fail. The vulnerability operates at the network protocol level and demonstrates a fundamental weakness in the application's security design philosophy, where the system prioritizes connectivity over security integrity. The flaw essentially creates a downgrade attack vector that undermines the security assurances provided by encryption protocols.
The technical implementation of this vulnerability involves the Address Book application's failure to maintain secure connection parameters when encountering network disruptions during encrypted CardDAV sessions. When an encrypted connection fails to establish or maintains an unstable state, the system automatically reverts to unencrypted communication without proper authentication or authorization verification. This behavior creates a window of opportunity for network sniffing attacks, where malicious actors can intercept and analyze the unencrypted data streams. The vulnerability specifically affects the CardDAV protocol implementation, which is used for contact synchronization and management between client applications and servers. The flaw manifests as a lack of proper security policy enforcement, where the system does not maintain the security context established during the initial encrypted session.
From an operational impact perspective, this vulnerability exposes sensitive personal and organizational contact data to passive network monitoring attacks. The unencrypted transmission of CardDAV data includes contact information, address details, phone numbers, email addresses, and other personally identifiable information that could be exploited for identity theft, social engineering attacks, or corporate espionage. The vulnerability is particularly concerning in environments where wireless networks are used, as these networks are inherently more susceptible to eavesdropping attacks. The attack vector requires minimal sophistication, as it only necessitates network interruption and packet sniffing capabilities, making it accessible to attackers with basic networking knowledge. This weakness effectively neutralizes the encryption protections that users expect when connecting to CardDAV servers, particularly in corporate environments where contact data may contain sensitive business information.
The security implications of CVE-2011-3444 align with CWE-310, which addresses cryptographic weaknesses and improper handling of security contexts. This vulnerability also maps to ATT&CK technique T1041, which covers network sniffing activities that can be used to capture sensitive data. The flaw represents a classic case of security by obscurity failing to provide adequate protection, as the system's automatic fallback mechanism creates an unintended attack surface. Organizations using affected Mac OS X versions face significant risks when connecting to CardDAV servers, particularly in untrusted network environments such as public Wi-Fi hotspots or shared office networks. The vulnerability highlights the importance of maintaining consistent security policies across all network communication channels and demonstrates the necessity of proper fallback mechanisms that do not compromise security. Remediation efforts should focus on implementing proper connection management protocols that maintain security context during network disruptions and ensuring that all network communications remain encrypted throughout the session lifecycle.