CVE-2007-4704 in Mac OS X
Summary
by MITRE
The Application Firewall in Apple Mac OS X 10.5 does not apply changed settings to processes that are started by launchd until the processes are restarted, which might allow attackers to bypass intended access restrictions.
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Analysis
by VulDB Data Team • 03/16/2021
The vulnerability described in CVE-2007-4704 represents a critical flaw in the implementation of Apple Mac OS X 10.5's Application Firewall system. This issue stems from a fundamental design weakness in how the firewall handles runtime configuration changes and their propagation to actively running processes. The vulnerability specifically affects the interaction between the firewall service and launchd, which is the system daemon responsible for managing the lifecycle of processes in Mac OS X environments. When administrators or users modify firewall rules through the graphical interface or command-line tools, these changes do not immediately take effect for processes that were already running under the launchd supervision.
The technical nature of this flaw can be categorized as a configuration management issue that violates the principle of least privilege and runtime security enforcement. The Application Firewall in Mac OS X 10.5 operates by maintaining a set of rules that control network access for applications, but the system fails to properly refresh or apply these rules to existing processes that were initiated before the rule changes occurred. This creates a window of opportunity where previously allowed network connections can continue to operate under the old rule set while new connections are properly restricted according to the updated configuration. The vulnerability manifests because the firewall service does not maintain proper synchronization between its configuration state and the runtime environments of processes that it is supposed to protect.
From an operational perspective, this vulnerability presents a significant risk to system security as it allows attackers to exploit the temporal gap between configuration changes and their effective application. An attacker who gains access to a system could potentially maintain persistent network access by leveraging processes that were started before firewall rules were updated, effectively bypassing the intended access restrictions. This weakness directly impacts the integrity of the system's network security posture and undermines the trust model that users place in firewall configurations. The vulnerability is particularly concerning because it operates silently without alerting system administrators to the bypass, making it difficult to detect and remediate. This issue aligns with CWE-691, which addresses insufficient control flow management, and represents a classic example of how process management and security configuration can become decoupled in operating system implementations.
The impact of this vulnerability extends beyond simple access bypass to potentially enable more sophisticated attack vectors including persistent backdoors, data exfiltration through established connections, and privilege escalation opportunities. Attackers could exploit this weakness by first establishing network connections through processes that were running before firewall rules were modified, then wait for the firewall to be reconfigured or for the system to restart before using the established channels for malicious activities. The attack surface is further expanded because this issue affects all network-dependent applications running under launchd, including system services and user applications that rely on network connectivity. Mitigation strategies should include implementing regular system restarts to force firewall rule refresh, monitoring for unauthorized network access patterns, and deploying additional network monitoring solutions to detect anomalies that might indicate rule bypass attempts. Organizations should also consider implementing layered security approaches that do not rely solely on the Application Firewall's configuration management for critical network access controls. This vulnerability demonstrates the importance of proper runtime security enforcement and the need for security systems to maintain consistent state across all active processes in the system.
The security implications of CVE-2007-4704 align with several ATT&CK tactics including privilege escalation through process manipulation and defense evasion by exploiting system configuration weaknesses. The vulnerability creates opportunities for attackers to maintain access through established network connections that were not properly restricted by updated firewall rules. System administrators should implement proactive monitoring for network connections that persist across firewall rule changes, and should consider implementing automated processes to ensure that firewall configurations are properly enforced across all running processes. The issue highlights the need for comprehensive security testing that includes runtime configuration validation and process state synchronization verification in operating system security implementations.