CVE-2016-4620 in iOS
Summary
by MITRE
The Sandbox Profiles component in Apple iOS before 10 does not properly restrict access to directory metadata for SMS draft directories, which allows attackers to discover text-message recipients via a crafted app.
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Analysis
by VulDB Data Team • 09/16/2022
The vulnerability identified as CVE-2016-4620 resides within Apple iOS versions prior to 10.0, specifically affecting the Sandbox Profiles component that governs application permissions and access controls. This flaw represents a significant privacy and security concern as it undermines the fundamental principle of sandboxing that isolates applications from each other and from system resources. The issue manifests in how the operating system handles directory metadata access controls for SMS draft directories, creating an unintended information disclosure channel that violates the principle of least privilege.
The technical implementation flaw involves improper access control enforcement within the iOS sandboxing framework. When applications attempt to access directory metadata for SMS draft storage locations, the system fails to adequately restrict these queries to only the application that owns the data. This oversight allows malicious applications to enumerate directory structures and potentially discover recipient information from text message drafts. The vulnerability stems from insufficient validation of access requests and inadequate boundary enforcement between application processes and system resources. According to CWE classification, this represents a weakness in access control mechanisms where directory metadata access is not properly restricted, falling under CWE-284 for improper access control.
The operational impact of this vulnerability extends beyond simple privacy concerns to encompass potential data leakage and social engineering opportunities. Attackers can craft malicious applications that exploit this weakness to discover text message recipients without explicit user consent, effectively bypassing iOS security boundaries. This information disclosure could enable targeted phishing attacks, social engineering campaigns, or other malicious activities that rely on knowledge of communication patterns and contacts. The vulnerability affects the core security model of iOS by allowing unauthorized access to metadata that should remain protected within the sandboxed environment. From an ATT&CK framework perspective, this represents a technique for privilege escalation and information gathering, specifically targeting the T1056.001 sub-technique related to input injection and T1566 for credential access through social engineering.
Mitigation strategies for CVE-2016-4620 require immediate system updates to iOS 10.0 or later versions where Apple has implemented proper access control restrictions for directory metadata. Organizations should conduct comprehensive security assessments to identify applications that may have exploited this vulnerability and ensure all iOS devices are updated to the latest supported versions. System administrators should monitor for suspicious application behavior that might indicate exploitation attempts and implement mobile device management policies that enforce security updates. The vulnerability highlights the critical importance of proper sandbox implementation and access control enforcement in mobile operating systems, where the isolation between applications and system resources forms the foundation of device security. Additionally, developers should review their applications for potential reliance on insecure directory access patterns and ensure compliance with iOS security guidelines that mandate proper sandboxing practices.