CVE-2007-4686 in Mac OS X
Summary
by MITRE
Integer signedness error in the ttioctl function in bsd/kern/tty.c in the xnu kernel in Apple Mac OS X 10.4 through 10.4.10 allows local users to cause a denial of service (system shutdown) or gain privileges via a crafted TIOCSETD ioctl request.
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Analysis
by VulDB Data Team • 07/31/2019
The vulnerability described in CVE-2007-4686 represents a critical integer signedness error within the xnu kernel's terminal handling subsystem on Apple Mac OS X versions 10.4 through 10.4.10. This flaw exists in the ttioctl function located in bsd/kern/tty.c, which is responsible for managing terminal device ioctls and controlling terminal behavior. The issue stems from improper handling of signed integer values when processing the TIOCSETD ioctl request, creating a condition where malicious input can trigger unexpected kernel behavior.
The technical implementation of this vulnerability involves a specific integer signedness error that occurs during the processing of terminal device control operations. When a local user crafts a malicious TIOCSETD ioctl request, the kernel's ttioctl function fails to properly validate the signedness of integer parameters, leading to potential buffer overflows or invalid memory access patterns. This flaw allows an attacker to manipulate the terminal subsystem in ways that can either cause system instability through denial of service or potentially escalate privileges by exploiting the kernel's handling of terminal control commands.
From an operational perspective, this vulnerability presents significant risks to system stability and security integrity. The local privilege escalation aspect means that unprivileged users could potentially gain administrative access to affected systems, while the denial of service component could result in complete system shutdown or reboot. The impact extends beyond simple system availability issues as the vulnerability affects the core kernel components that manage terminal I/O operations, which are fundamental to system operation. This type of vulnerability is particularly dangerous in multi-user environments where local access could be exploited by malicious users with minimal privileges.
The vulnerability aligns with CWE-190, which describes integer overflow and underflow conditions, and demonstrates how improper integer handling can lead to security flaws in kernel code. From an ATT&CK framework perspective, this vulnerability maps to privilege escalation techniques through kernel exploitation and system shutdown capabilities. The attack vector requires local access to the system but can result in either elevation of privileges or denial of service, making it a particularly attractive target for attackers seeking to compromise system integrity. Organizations should implement immediate mitigations including system updates, kernel hardening measures, and monitoring for unauthorized local access attempts.
Mitigation strategies for this vulnerability should prioritize the immediate deployment of Apple's security patches and updates for affected Mac OS X versions. System administrators should also consider implementing additional security controls such as restricting local user privileges, monitoring terminal I/O operations, and establishing robust audit trails for ioctl operations. The vulnerability's nature suggests that kernel-level security measures should be strengthened through proper input validation and integer parameter checking in all terminal device handling code. Regular security assessments and kernel integrity monitoring should be implemented to detect similar issues in other system components and prevent exploitation of related vulnerabilities.