CVE-2019-8841 in iOS
Summary
by MITRE • 10/28/2020
An information disclosure issue was addressed by removing the vulnerable code. This issue is fixed in iOS 13.3 and iPadOS 13.3. An application may be able to execute arbitrary code with kernel privileges.
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Analysis
by VulDB Data Team • 11/29/2020
This vulnerability represents a critical information disclosure flaw that existed in Apple's iOS and iPadOS operating systems prior to version 13.3. The issue stemmed from a code path that allowed malicious applications to potentially extract sensitive kernel-level information through improper access controls. The vulnerability was classified as a privilege escalation vector that could enable an attacker to gain unauthorized access to kernel memory spaces and execute arbitrary code with the highest system privileges. This type of flaw falls under the category of kernel-level information disclosure vulnerabilities that can serve as a foundation for more sophisticated attacks. The vulnerability was particularly concerning because it could be exploited by malicious applications that had already gained some level of user access, potentially allowing them to escalate their privileges to kernel level.
The technical implementation of this vulnerability involved a specific code path within the operating system's kernel that failed to properly validate memory access requests from user-space applications. When an application attempted to access certain kernel memory regions through improper system calls or memory manipulation techniques, the kernel would inadvertently expose sensitive information or allow unauthorized execution of code. This flaw was particularly dangerous because it bypassed normal security boundaries that should have prevented user applications from accessing kernel-level resources. The vulnerability was addressed by completely removing the problematic code sections that enabled this information disclosure and privilege escalation capability. This remediation approach aligns with common practices in kernel security where vulnerable code paths are eliminated rather than patched, as the complexity of kernel-level security makes removal the most reliable solution.
The operational impact of this vulnerability was significant for users of affected iOS and iPadOS versions, as it created a potential attack vector that could be exploited by malicious applications or malware. Attackers could leverage this vulnerability to gain root-level access to devices, potentially allowing them to install persistent backdoors, extract all device data, monitor user activities, or modify system security controls. The vulnerability was particularly concerning in enterprise environments where iOS devices were used for sensitive business operations, as it could enable attackers to compromise entire device fleets. This type of vulnerability is categorized under CWE-200 (Information Exposure) and could potentially map to ATT&CK techniques such as privilege escalation and persistence mechanisms. The fix required users to update to iOS 13.3 or iPadOS 13.3, which involved not just patching the code but also ensuring that all kernel-level memory access controls were properly enforced.
The resolution of this vulnerability demonstrates Apple's approach to addressing kernel-level security issues through complete code removal rather than partial patches. This methodology is consistent with industry best practices for critical kernel vulnerabilities where the risk of incomplete fixes or side effects from partial patches outweighs the benefits. The vulnerability's existence highlights the ongoing challenge in mobile security where applications must be carefully sandboxed from kernel-level resources while maintaining system functionality. Security researchers who discovered this flaw likely used advanced memory analysis techniques and kernel debugging methods to identify the specific code paths that enabled the information disclosure. The remediation process required careful testing to ensure that legitimate system functionality was preserved while eliminating the security gap. This vulnerability serves as a reminder of the critical importance of kernel security in mobile operating systems and the need for continuous security auditing of low-level system components to prevent similar issues from arising in the future.