CVE-2016-7583 in iCloud
Summary
by MITRE
An issue was discovered in certain Apple products. iCloud before 6.0.1 is affected. The issue involves the setup subsystem in the "iCloud" component. It allows local users to gain privileges via a crafted dynamic library in an unspecified directory.
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Analysis
by VulDB Data Team • 06/03/2020
The vulnerability identified as CVE-2016-7583 represents a critical privilege escalation flaw within Apple's iCloud setup subsystem affecting versions prior to 6.0.1. This issue resides in the iCloud component of Apple's operating systems and specifically targets the setup subsystem which handles the initial configuration and authentication processes for iCloud services. The vulnerability stems from improper handling of dynamic library loading mechanisms within the iCloud setup process, creating an exploitable condition that allows local attackers to elevate their privileges through malicious code execution.
The technical implementation of this vulnerability involves a flaw in the dynamic library loading process where the iCloud setup subsystem fails to properly validate or restrict the loading of shared libraries from unspecified directories. Attackers can craft malicious dynamic libraries and place them in targeted locations within the system filesystem, typically in directories that are automatically searched during the setup process. When the iCloud setup subsystem executes, it loads these crafted libraries with elevated privileges, effectively allowing the malicious code to run with root-level permissions. This represents a classic privilege escalation vulnerability where local user access can be leveraged to achieve system-level control.
From an operational impact perspective, this vulnerability poses significant security risks to Apple device users as it enables attackers with local access to potentially compromise entire systems. The exploitation requires only local user privileges and does not necessitate network connectivity or complex attack vectors, making it particularly dangerous in environments where physical access to devices is possible. The vulnerability can be exploited to install persistent backdoors, exfiltrate sensitive data, modify system configurations, or establish unauthorized access points within the device. Security researchers have classified this as a high-severity issue due to its potential for system compromise and the relative ease of exploitation.
The vulnerability aligns with CWE-427 Uncontrolled Search Path Element, which describes situations where applications search for libraries or executables in directories that can be manipulated by attackers. This weakness specifically manifests when applications use relative paths or allow user-controlled paths to be included in their search sequences. The ATT&CK framework categorizes this as Privilege Escalation through Dynamic Linking, where adversaries leverage legitimate system tools and processes to execute malicious code with elevated privileges. Organizations should implement immediate mitigations including updating to iCloud 6.0.1 or later, implementing strict file system permissions, monitoring for unauthorized library placements, and conducting security audits to identify potential exploitation attempts. System administrators should also consider restricting local user privileges and implementing additional monitoring controls to detect anomalous library loading behaviors that could indicate exploitation attempts.