CVE-2012-3728 in iOS
Summary
by MITRE
The kernel in Apple iOS before 6 dereferences invalid pointers during the handling of packet-filter data structures, which allows local users to gain privileges via a crafted program that makes packet-filter ioctl calls.
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Analysis
by VulDB Data Team • 04/13/2021
The vulnerability described in CVE-2012-3728 represents a critical kernel-level flaw in Apple iOS versions prior to 6.0 that stems from improper handling of packet-filter data structures within the operating system kernel. This issue manifests when the kernel processes packet-filter ioctl system calls, which are typically used for network packet filtering and manipulation. The flaw occurs during the processing of these specific data structures where the kernel fails to properly validate pointer references, leading to invalid memory access conditions that can be exploited by malicious programs.
This vulnerability falls under the category of improper pointer validation and memory management issues, which are commonly classified as CWE-467 and CWE-476 in the Common Weakness Enumeration framework. The technical implementation involves the kernel's packet-filter subsystem where it handles ioctl commands that manipulate network filtering rules. When a crafted program submits malicious packet-filter ioctl calls, the kernel's handling of these requests leads to dereferencing invalid memory pointers, creating a condition where arbitrary code execution becomes possible.
The operational impact of this vulnerability is severe as it allows local users to escalate privileges from standard user-level access to kernel-level privileges. This privilege escalation occurs because the invalid pointer dereference can be manipulated to redirect execution flow within the kernel space, potentially enabling attackers to execute arbitrary code with the highest system privileges. The exploit requires local access and a crafted program capable of making packet-filter ioctl calls, making it particularly dangerous in environments where users might have the ability to run arbitrary code on the system.
The attack vector for this vulnerability is specifically through the packet-filter ioctl interface, which is part of the network subsystem's configuration capabilities. Attackers would need to create a malicious program that makes specific ioctl calls to the packet-filter subsystem, triggering the kernel's improper pointer handling. This aligns with the ATT&CK framework's privilege escalation techniques where adversaries leverage kernel vulnerabilities to gain elevated system access. The vulnerability demonstrates how seemingly routine network configuration interfaces can become attack surfaces when proper input validation and memory management practices are not implemented.
Mitigation strategies for this vulnerability include updating to iOS 6.0 or later versions where Apple has addressed the kernel memory management issues in the packet-filter subsystem. System administrators should also implement network segmentation and access controls to limit the potential impact of local privilege escalation attacks. Additionally, monitoring for unusual packet-filter ioctl activity could help detect potential exploitation attempts. The fix implemented by Apple likely involved strengthening pointer validation checks within the kernel's packet-filter handling code and ensuring proper memory management when processing ioctl commands, preventing the invalid pointer dereference conditions that enabled privilege escalation.