CVE-2018-4172 in iOS
Summary
by MITRE
An issue was discovered in certain Apple products. iOS before 11.3 is affected. The issue involves the "Find My iPhone" component. It allows physically proximate attackers to bypass the iCloud password requirement for disabling the "Find My iPhone" feature via vectors involving a backup restore.
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Analysis
by VulDB Data Team • 02/06/2021
The vulnerability identified as CVE-2018-4172 represents a significant security flaw within Apple's Find My iPhone functionality affecting iOS versions prior to 11.3. This weakness resides in the iCloud account security mechanisms that protect the Find My iPhone feature, which is designed to help users locate and secure their lost or stolen devices. The vulnerability specifically targets the authentication process required to disable this protective feature, creating a pathway for attackers who have physical access to a device to bypass the standard iCloud password verification requirements. The attack vector involves a backup restore process that allows malicious actors to manipulate the device state in a way that circumvents the normal security protocols. This issue demonstrates a critical failure in Apple's security model where physical proximity can be exploited to undermine cloud-based device protection mechanisms.
The technical implementation of this vulnerability stems from insufficient validation within the Find My iPhone disable process during backup restoration operations. When a device undergoes a backup restore, the system should enforce strict authentication requirements to ensure that only authorized users can modify critical security settings. However, the flaw allows attackers to exploit the restore process to effectively bypass the iCloud password requirement that normally protects against unauthorized modifications to the Find My iPhone feature. This represents a weakness in the authentication flow that should maintain consistent security posture regardless of the device state or recovery operations being performed. The vulnerability operates at the intersection of local device manipulation and cloud account security, creating a scenario where physical access can be leveraged to undermine remote account protection mechanisms. The attack requires only physical proximity to the device, making it particularly concerning as it can be executed without sophisticated technical skills or network access.
The operational impact of CVE-2018-4172 extends beyond simple device theft scenarios to encompass broader security implications for iCloud account protection and device recovery mechanisms. Attackers who gain physical access to an iOS device before iOS 11.3 can potentially disable Find My iPhone without knowing the iCloud password, rendering the device completely untraceable and secure from legitimate account holders. This vulnerability undermines the fundamental security promise of iCloud-based device tracking and protection, as it allows malicious actors to completely remove the device from the owner's control. The implications are particularly severe given that Find My iPhone serves as a primary tool for locating lost devices and preventing unauthorized use of stolen property. The vulnerability also affects the broader ecosystem of Apple's security architecture by demonstrating how backup and restore operations can be manipulated to bypass authentication controls that are meant to be invariant across different device states and recovery scenarios.
This vulnerability aligns with CWE-284, which addresses improper access control, and represents a specific instance where inadequate authentication controls allow unauthorized modifications to security-critical settings. The flaw also maps to ATT&CK technique T1484.001 which covers "Cloud Account Permissions" and demonstrates how physical access can be leveraged to manipulate cloud-based security features through device recovery mechanisms. Apple's implementation failed to maintain consistent authentication requirements across all device states, creating a gap where backup operations could be exploited to bypass normal security controls. The vulnerability highlights the importance of maintaining security posture consistency during device recovery operations and underscores the need for comprehensive authentication validation regardless of the operational context. Organizations and individuals relying on iCloud protection mechanisms were left vulnerable to unauthorized access and device manipulation, particularly in scenarios involving lost or stolen devices where physical access could be gained by malicious actors. The remediation required a system update that addressed the authentication flow during backup restore operations, ensuring that the iCloud password requirement remains enforced regardless of the device state or recovery process being executed.
The mitigation strategy for CVE-2018-4172 required users to update their iOS devices to version 11.3 or later, where Apple implemented fixes to the authentication flow during backup restore operations. This update addressed the specific weakness in the Find My iPhone disable process by ensuring that iCloud password verification remains mandatory even during backup restoration. The fix likely involved strengthening the validation checks within the device recovery process to prevent bypass of authentication requirements through backup operations. Security practitioners should emphasize the importance of maintaining up-to-date system software to protect against known vulnerabilities and ensure that all authentication mechanisms remain effective across different operational contexts. The vulnerability serves as a reminder of the critical importance of consistent security controls throughout the entire device lifecycle, including during recovery and restoration operations. Organizations should implement policies requiring regular system updates and maintain awareness of security advisories to protect against similar vulnerabilities that could exploit gaps in authentication controls during device recovery scenarios.