CVE-2019-8744 in iOS
Summary
by MITRE • 10/28/2020
A memory corruption issue existed in the handling of IPv6 packets. This issue was addressed with improved memory management. This issue is fixed in macOS Catalina 10.15, tvOS 13, macOS Catalina 10.15.1, Security Update 2019-001, and Security Update 2019-006, watchOS 6, iOS 13. A malicious application may be able to determine kernel memory layout.
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Analysis
by VulDB Data Team • 11/28/2020
The vulnerability described in CVE-2019-8744 represents a critical memory corruption flaw within the IPv6 packet handling mechanisms of Apple's operating systems. This issue specifically affects the kernel-level processing of IPv6 network packets, where improper memory management leads to potential corruption of kernel memory structures. The vulnerability arises from insufficient validation and handling of malformed or specially crafted IPv6 packets that could be transmitted through network interfaces, creating opportunities for exploitation that extend beyond simple denial of service scenarios.
The technical implementation of this flaw demonstrates poor memory management practices during IPv6 packet processing within the kernel space of Apple's operating systems. When the system receives IPv6 packets containing malformed headers or unexpected packet structures, the kernel's memory allocation and deallocation routines fail to properly validate input parameters, leading to memory corruption that can manifest as buffer overflows, use-after-free conditions, or other memory integrity violations. This type of vulnerability falls under the CWE-125 weakness category, which specifically addresses out-of-bounds read conditions, and aligns with CWE-787, which covers out-of-bounds write vulnerabilities that can occur during memory management operations.
The operational impact of CVE-2019-8744 extends beyond traditional network security concerns into the realm of kernel-level exploitation capabilities. A malicious application with the ability to send crafted IPv6 packets could potentially leverage this vulnerability to determine kernel memory layout information, which represents a significant escalation from typical network-based attacks. This memory layout information disclosure enables attackers to perform advanced exploitation techniques such as return-oriented programming attacks, kernel address space layout randomization bypasses, and other sophisticated attacks that require precise knowledge of memory structures. The ATT&CK framework categorizes this type of vulnerability under T1068, which addresses local privilege escalation through kernel exploits, and T1082, which covers system information discovery techniques that can be used to gather intelligence for further exploitation.
The remediation efforts for this vulnerability required comprehensive updates to Apple's operating systems, including macOS Catalina 10.15 and subsequent security updates, along with corresponding updates for tvOS, watchOS, and iOS platforms. These updates implemented improved memory management routines that include enhanced input validation, proper bounds checking for IPv6 packet headers, and more robust handling of edge cases in packet processing. The security updates specifically address the memory corruption patterns that allowed attackers to gain information about kernel memory layouts, thereby preventing the exploitation pathways that could lead to full system compromise. The fix demonstrates the importance of proper memory management in kernel-level code and the necessity of comprehensive testing for network protocol handling routines, particularly in environments where untrusted network input is processed.
This vulnerability exemplifies the critical nature of kernel-level security flaws in modern operating systems, where network protocol handling represents one of the most attack-prone areas due to the constant exposure to external network traffic. The fact that this issue could be exploited by malicious applications highlights the need for comprehensive security testing of all kernel interfaces, particularly those involved in network processing. Organizations should ensure that all affected systems receive the appropriate security updates and that network monitoring solutions are configured to detect unusual IPv6 packet patterns that might indicate exploitation attempts. The remediation process for such vulnerabilities typically requires careful consideration of system compatibility and the potential for update-related disruptions, particularly in enterprise environments where multiple operating system versions may be in use simultaneously.