CVE-2007-4685 in Mac OS X
Summary
by MITRE
The kernel in Apple Mac OS X 10.4 through 10.4.10 allows local users to gain privileges by executing setuid or setgid programs in which the stdio, stderr, or stdout file descriptors are "in an unexpected state."
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Analysis
by VulDB Data Team • 07/31/2019
This vulnerability exists in the kernel implementation of Apple Mac OS X versions 10.4 through 10.4.10 where the privilege escalation occurs through improper handling of file descriptor states during program execution. The flaw specifically targets the standard input output streams stdin, stdout, and stderr when these file descriptors are in an unexpected state, allowing local attackers to exploit the system's privilege management mechanisms. The vulnerability stems from the kernel's failure to properly validate the state of these critical file descriptors before executing setuid or setgid programs, which are designed to run with elevated privileges. When these file descriptors are not in their expected initial state, the kernel's privilege checking logic becomes bypassed, creating a path for privilege escalation attacks.
The technical implementation of this vulnerability relates to the kernel's process management and privilege handling subsystem. In normal operation, setuid and setgid programs are executed with the privileges of the file owner or group rather than the user executing them. However, when stdio file descriptors are in an unexpected state, the kernel's privilege validation routines fail to properly enforce the security boundaries. This creates a condition where malicious code can manipulate the file descriptor state to bypass security checks that normally prevent privilege escalation. The vulnerability is classified under CWE-276, which deals with improper privileges, and specifically relates to improper file descriptor handling in privilege contexts. The attack vector requires local system access and involves crafting a program or manipulating existing programs to place file descriptors in the unexpected state before execution.
The operational impact of this vulnerability is significant as it allows local users to escalate their privileges from standard user level to root access without requiring any special authentication or network connectivity. An attacker can leverage this weakness to execute arbitrary code with elevated privileges, potentially leading to complete system compromise. The vulnerability affects all Mac OS X versions in the 10.4.x series, which were widely deployed in enterprise and consumer environments during that period. The exploitation process typically involves creating or modifying programs to manipulate file descriptor states before execution, making it particularly dangerous in environments where users might have access to system utilities or development tools. This vulnerability directly aligns with ATT&CK technique T1068, which covers privilege escalation through the exploitation of system vulnerabilities.
Mitigation strategies for this vulnerability include immediate installation of Apple's security patches that address the kernel's file descriptor handling logic. System administrators should ensure all Mac OS X systems in the 10.4.x range are updated to the latest available security releases. Additionally, monitoring for unauthorized program execution and file descriptor manipulation can help detect potential exploitation attempts. The recommended approach involves implementing proper system hardening measures, including restricting local user access to critical system utilities and monitoring for unusual privilege escalation patterns. Organizations should also consider implementing privilege separation mechanisms and ensuring that setuid/setgid programs are properly audited and maintained to prevent exploitation of similar vulnerabilities in the future. This vulnerability underscores the importance of proper kernel security implementation and the critical need for thorough testing of privilege management systems under various file descriptor states.