CVE-2016-7576 in iOS
Summary
by MITRE
In iOS before 9.3.3, a memory corruption issue existed in the kernel. This issue was addressed through improved memory handling.
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Analysis
by VulDB Data Team • 04/28/2020
The vulnerability identified as CVE-2016-7576 represents a critical memory corruption flaw within the iOS kernel that affected versions prior to 9.3.3. This type of vulnerability falls under the category of kernel-level security issues that can have profound implications for device security and stability. The flaw existed in the memory management subsystem of the operating system, specifically within the kernel components that handle memory allocation and deallocation processes. Such vulnerabilities are particularly dangerous because they operate at the lowest level of the operating system where they can bypass traditional user-space security mechanisms and directly impact system integrity.
The technical nature of this memory corruption issue stems from improper memory handling within the kernel's memory management functions. When the kernel processes memory operations, it must ensure proper allocation, deallocation, and access control to prevent unauthorized memory access or corruption. The flaw likely manifested through insufficient bounds checking or improper memory pointer validation during kernel operations, creating potential opportunities for attackers to exploit memory corruption patterns. This type of vulnerability is classified under CWE-125 as "Out-of-bounds Read" and potentially CWE-787 as "Out-of-bounds Write" depending on the specific implementation details. The memory corruption could have enabled attackers to execute arbitrary code with kernel-level privileges, effectively compromising the entire device.
The operational impact of this vulnerability extends beyond simple memory corruption to encompass significant security risks for iOS devices. Attackers who could successfully exploit this flaw would gain elevated privileges within the kernel, potentially enabling them to bypass security mechanisms such as code signing, sandboxing, and other kernel-level protections. This would allow for complete system compromise, data exfiltration, and persistent backdoor installation. The vulnerability's presence in iOS versions prior to 9.3.3 meant that millions of devices were potentially exposed to attacks that could leverage this memory corruption to gain unauthorized access. The exploitation of such kernel-level vulnerabilities aligns with tactics described in the MITRE ATT&CK framework under the T1059 technique for Command and Scripting Interpreter, as attackers could potentially execute malicious code with the highest system privileges.
Apple addressed this vulnerability through comprehensive memory handling improvements in iOS 9.3.3, implementing enhanced bounds checking and memory management protocols within the kernel. These improvements likely included stricter memory validation procedures, better pointer integrity checks, and enhanced memory allocation mechanisms to prevent the conditions that led to the corruption. The fix represents a typical approach to kernel memory corruption vulnerabilities where the root cause is addressed through defensive programming techniques and improved memory management controls. Organizations and users should prioritize updating to iOS 9.3.3 or later versions to mitigate this risk, as the vulnerability could have been exploited through various attack vectors including malicious applications, web-based attacks, or other kernel-level exploitation techniques. The resolution demonstrates the importance of regular security updates and kernel-level security hardening in maintaining device integrity against sophisticated threats.