CVE-2007-4703 in Mac OS X
Summary
by MITRE
The Application Firewall in Apple Mac OS X 10.5 does not prevent a root process from accepting incoming connections, even when "Block incoming connections" has been set for its associated executable, which might allow remote attackers or local root processes to bypass intended access restrictions.
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Analysis
by VulDB Data Team • 03/16/2021
The vulnerability described in CVE-2007-4703 represents a critical design flaw in the Application Firewall implementation of Apple Mac OS X 10.5 operating system. This security weakness specifically targets the firewall's ability to enforce access controls for root processes, creating a significant bypass mechanism that undermines the intended security posture of the system. The flaw manifests when the firewall is configured to block incoming connections for specific executables, yet fails to properly restrict root processes from accepting network connections regardless of these settings. This fundamental failure in access control enforcement creates a dangerous scenario where malicious actors can circumvent network security policies that should otherwise protect the system from unauthorized network access.
The technical nature of this vulnerability stems from the improper handling of privilege levels within the firewall subsystem. When a root process attempts to establish or accept incoming network connections, the firewall mechanism does not adequately verify whether the process should be permitted to bypass the configured restrictions. This behavior violates the principle of least privilege and demonstrates a failure in the security model implementation. The vulnerability operates at the kernel level where process privileges are evaluated, making it particularly dangerous as it can be exploited by both local root users and remote attackers who have gained root access. According to CWE classification, this represents a weakness in privilege management where the system fails to properly enforce access control decisions based on process identity and privilege levels.
The operational impact of CVE-2007-4703 is substantial as it allows attackers to bypass network security controls that are specifically designed to protect against unauthorized access. A local root process can establish network connections that would normally be blocked, effectively creating a backdoor mechanism that circumvents the firewall's intended protection. This vulnerability can be exploited by attackers who have already achieved root access to the system, enabling them to maintain persistence and establish command and control channels without detection. The implications extend beyond simple network access bypass, as it can facilitate lateral movement within networks and enable more sophisticated attack patterns that rely on maintaining stealthy network communications. From an ATT&CK framework perspective, this vulnerability maps to privilege escalation techniques and defense evasion methods, as it allows adversaries to bypass network-based security controls that would normally detect and prevent malicious network activity.
Mitigation strategies for this vulnerability require careful consideration of both immediate and long-term security measures. System administrators should implement comprehensive monitoring of network connections from root processes to detect anomalous behavior that might indicate exploitation attempts. The recommended approach involves disabling unnecessary network services, implementing additional host-based security controls, and ensuring that the firewall is configured with the most restrictive settings possible. Organizations should also consider implementing network segmentation and additional monitoring solutions that can detect unauthorized network access attempts. Given that this is a privilege escalation vulnerability, it is essential to maintain strict access controls and regularly audit system configurations to ensure that only authorized processes have the necessary privileges to accept incoming network connections. The vulnerability also highlights the importance of keeping operating systems updated and implementing layered security approaches that do not rely solely on a single security control mechanism to protect against exploitation attempts.