CVE-2007-0752 in Mac OS X
Summary
by MITRE
The PPP daemon (pppd) in Apple Mac OS X 10.4.8 checks ownership of the stdin file descriptor to determine if the invoker has sufficient privileges, which allows local users to load arbitrary plugins and gain root privileges by bypassing this check.
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Analysis
by VulDB Data Team • 03/23/2025
The vulnerability described in CVE-2007-0752 resides within the Point-to-Point Protocol daemon implementation in Apple Mac OS X 10.4.8, specifically targeting the privilege escalation mechanism during plugin loading operations. This flaw represents a classic case of insufficient privilege checking that directly undermines the security model of the operating system's network services. The pppd daemon, which handles point-to-point protocol connections and is integral to dial-up networking and VPN functionality, implements a security check that examines the ownership of the stdin file descriptor to verify whether the invoking user possesses adequate privileges. This design decision creates a critical weakness that can be exploited by local attackers to bypass the intended access controls and elevate their privileges to root level.
The technical exploitation of this vulnerability hinges on the daemon's flawed privilege validation logic. When pppd executes, it performs a check on the stdin file descriptor to determine if the calling process belongs to a privileged user. However, this check can be circumvented through manipulation of file descriptor inheritance or by creating specific conditions that allow an unprivileged user to effectively impersonate a privileged process. The vulnerability stems from the daemon's reliance on file descriptor ownership rather than robust authentication mechanisms, making it susceptible to manipulation by local attackers who can craft malicious plugin loading scenarios. This type of flaw aligns with CWE-284, which categorizes improper access control issues, and represents a direct violation of the principle of least privilege that should govern system security.
The operational impact of this vulnerability extends beyond simple privilege escalation to encompass potential system compromise and unauthorized access to sensitive network resources. Local users who exploit this vulnerability can load arbitrary plugins into the pppd daemon, effectively gaining root access to the system and enabling them to modify critical system files, install malicious software, or establish persistent backdoors. The implications are particularly severe because the PPP daemon is a core system service that typically runs with elevated privileges, and the ability to bypass its privilege checks creates a direct path to complete system control. This vulnerability can be exploited in various scenarios including social engineering attacks where an attacker might trick a user into executing a malicious script that leverages the daemon's flawed behavior, or through direct exploitation in compromised environments.
Mitigation strategies for this vulnerability must address both the immediate security gap and broader system hardening measures. The most effective immediate solution involves applying the official security patch provided by Apple, which corrects the privilege checking mechanism in the pppd daemon implementation. System administrators should also implement monitoring for suspicious plugin loading activities and file descriptor manipulations that might indicate exploitation attempts. The vulnerability highlights the importance of proper input validation and privilege checking in system services, aligning with ATT&CK technique T1068 which covers privilege escalation through local exploit techniques. Additional protective measures include restricting access to the pppd daemon, implementing proper file system permissions, and conducting regular security audits of system services that handle user input. Organizations should also consider implementing privilege separation mechanisms and ensuring that system services do not unnecessarily inherit elevated privileges, thereby reducing the potential impact of similar vulnerabilities in other components.