CVE-2011-3442 in iOS
Summary
by MITRE
The kernel in Apple iOS before 5.0.1 does not ensure the validity of flag combinations for an mmap system call, which allows local users to execute arbitrary unsigned code via a crafted app.
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Analysis
by VulDB Data Team • 11/26/2021
The vulnerability identified as CVE-2011-3442 represents a critical kernel-level flaw in Apple iOS versions prior to 5.0.1 that stems from insufficient validation of memory mapping flag combinations within the mmap system call implementation. This weakness exists at the core of the operating system's memory management subsystem and demonstrates a classic example of improper input validation that can be exploited by malicious actors. The issue falls under the broader category of kernel vulnerabilities that can be leveraged for privilege escalation attacks, where local users can manipulate system calls to gain unauthorized code execution capabilities. The vulnerability is particularly concerning because it affects the fundamental memory management mechanisms that underpin all applications running on the iOS platform, creating a potential attack surface that could be exploited to compromise the entire operating system.
The technical root cause of this vulnerability lies in the kernel's failure to properly validate flag combinations when processing mmap system calls, which are essential for mapping memory regions in Unix-like operating systems. When applications request memory mapping operations through the mmap system call, they specify various flags that control how memory is allocated, mapped, and accessed. In the affected iOS versions, the kernel did not adequately verify that the combination of these flags was valid and consistent with the intended memory management behavior. This validation gap allowed attackers to craft specific combinations of memory mapping flags that would bypass normal kernel security checks and potentially lead to memory corruption or arbitrary code execution. The vulnerability is classified as a buffer overflow condition under CWE-121 and represents a form of memory corruption that can be exploited through improper system call handling.
The operational impact of this vulnerability extends beyond simple code execution, as it enables local privilege escalation attacks that can potentially allow malicious applications to gain root-level access to the iOS system. Attackers who can successfully exploit this vulnerability can execute unsigned code with elevated privileges, effectively bypassing the normal security restrictions that protect the iOS ecosystem. This capability undermines the fundamental security model of iOS, which relies on code signing and sandboxing to prevent unauthorized execution. The attack vector requires local access to the device since the vulnerability exists within the kernel and is not exposed through network interfaces. However, this local execution requirement does not diminish the severity of the vulnerability, as it can be exploited through malicious applications that are already installed on the device or through social engineering techniques that trick users into installing compromised applications.
Mitigation strategies for this vulnerability primarily focus on updating to iOS 5.0.1 or later versions where Apple has implemented proper validation of mmap flag combinations. System administrators and users should prioritize applying the security update immediately upon release, as the vulnerability can be exploited without user interaction once an attacker has local access to a device. Additional defensive measures include implementing strict application sandboxing policies, monitoring for unusual memory mapping activities, and maintaining comprehensive system monitoring to detect potential exploitation attempts. The vulnerability demonstrates the importance of proper kernel validation and highlights the need for thorough security testing of system call implementations. Organizations should also consider implementing mobile device management solutions that can enforce security policies and ensure timely patch deployment across all managed devices. This vulnerability serves as a reminder of the critical importance of kernel-level security validation and proper input sanitization in preventing privilege escalation attacks that can compromise entire operating system architectures.