CVE-2016-4746 in iOS
Summary
by MITRE
The Keyboards component in Apple iOS before 10 does not properly use a cache for auto-correct suggestions, which allows remote attackers to obtain sensitive information in opportunistic circumstances by leveraging an unintended correction.
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Analysis
by VulDB Data Team • 09/16/2022
The vulnerability identified as CVE-2016-4746 resides within Apple iOS versions prior to 10.0, specifically affecting the Keyboards component that handles auto-correct functionality. This flaw represents a significant security concern as it demonstrates how seemingly benign text input features can be exploited to extract sensitive information from devices. The issue manifests when the system fails to properly utilize a cache mechanism for auto-correct suggestions, creating an unintended pathway for information disclosure. The vulnerability operates under opportunistic conditions, meaning attackers can exploit it without requiring elevated privileges or specific user interaction beyond normal text input operations.
The technical root cause of this vulnerability stems from improper cache management within the auto-correct system. When users type text, the keyboard component maintains a cache of suggested corrections to improve typing efficiency. However, in affected iOS versions, this cache implementation contains a flaw that allows attackers to access cached auto-correct data that should remain private. The vulnerability specifically relates to how the system handles the storage and retrieval of these suggestions, creating a scenario where sensitive information may be inadvertently exposed through the correction mechanism. This behavior aligns with CWE-200, which addresses improper exposure of sensitive information, and demonstrates how application-level cache management can introduce security risks. The flaw essentially creates a side-channel attack vector where the auto-correct feature becomes a conduit for information leakage.
The operational impact of CVE-2016-4746 extends beyond simple information disclosure, as it represents a fundamental weakness in how iOS handles user input processing. Attackers can potentially exploit this vulnerability to extract personal data, communication patterns, or other sensitive information that users have typed into their devices. The opportunistic nature of the attack means that exploitation can occur without requiring user interaction, making it particularly dangerous in environments where devices are left unattended or where network-based attacks are possible. This vulnerability directly impacts the confidentiality aspect of the CIA triad and can be categorized under the ATT&CK technique T1552.001, which covers "Unsecured Credentials" through the exploitation of application-level data caching mechanisms. The vulnerability affects all iOS devices running versions before 10.0, representing a substantial attack surface that could be leveraged by threat actors in various scenarios including mobile device compromise and privacy invasion.
Mitigation strategies for this vulnerability primarily involve updating to iOS 10.0 or later versions where Apple has addressed the cache management issue within the Keyboards component. Users should implement immediate patch management protocols to ensure their devices receive the security updates that resolve this flaw. Additionally, organizations should conduct vulnerability assessments to identify affected devices and establish monitoring procedures to detect potential exploitation attempts. The fix implemented by Apple likely involved strengthening the cache invalidation mechanisms and ensuring proper isolation of auto-correct data to prevent unintended information leakage. Security teams should also consider implementing device monitoring solutions that can detect anomalous keyboard behavior patterns that might indicate exploitation attempts. This vulnerability serves as a reminder of the importance of proper input validation and cache management in mobile operating systems, particularly when dealing with features that process user data in real-time. The remediation process should include comprehensive testing to ensure that the updated keyboard component properly handles sensitive data while maintaining the intended functionality of auto-correct features.