CVE-2024-40853 in iOS
Summary
by MITRE • 10/28/2024
This issue was addressed by restricting options offered on a locked device. This issue is fixed in iOS 18 and iPadOS 18. An attacker may be able to use Siri to enable Auto-Answer Calls.
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Analysis
by VulDB Data Team • 10/28/2024
The vulnerability described in CVE-2024-40853 represents a security flaw in Apple's iOS and iPadOS operating systems that allows unauthorized access to device calling features through voice commands while the device is locked. This issue specifically affects versions prior to iOS 18 and iPadOS 18, where the security restrictions on voice-activated services were insufficiently enforced. The flaw enables attackers to bypass normal device lock mechanisms and potentially compromise user privacy and security through automated calling functions. The vulnerability falls under the category of improper access control as defined by CWE-284, where insufficient restrictions are placed on access to device features that should remain protected when the device is secured. The issue is particularly concerning because it exploits the natural user interface elements that are designed to be convenient while simultaneously providing security risks.
The technical implementation of this vulnerability stems from how the operating system handles voice command processing when a device is in a locked state. Normally, when a device is secured, certain features including calling capabilities should be restricted to prevent unauthorized use. However, the flaw in the system allowed Siri to process specific voice commands that would enable Auto-Answer Calls even when the device was locked. This represents a breakdown in the security model where voice-activated services bypassed the normal authentication and authorization checks that should occur when a device is secured. The vulnerability could be exploited through carefully crafted voice commands that would trigger the Auto-Answer functionality without requiring proper authentication, effectively creating a backdoor access method to calling features.
The operational impact of this vulnerability extends beyond simple privacy concerns to encompass potential security threats including unauthorized communication, data exfiltration through phone calls, and social engineering attacks. Attackers could potentially use this vulnerability to make unauthorized calls, access voicemail systems, or even trigger emergency services without proper authorization. The threat landscape is further complicated by the fact that voice commands are often considered a legitimate and secure method of device interaction, making the exploitation of this vulnerability more subtle and harder to detect. This vulnerability aligns with ATT&CK technique T1203 - Exploitation for Client Execution, where attackers leverage legitimate system features to execute unauthorized actions, and T1566 - Phishing, as the attack vector could involve social engineering to trick users into enabling certain conditions that make the vulnerability exploitable.
The mitigation for this vulnerability requires updating to iOS 18 or iPadOS 18, where Apple has implemented proper restrictions on voice command processing when devices are locked. The fix addresses the underlying access control issue by ensuring that voice-activated services cannot trigger privileged functions without proper authentication. Organizations should ensure all devices are updated to the latest versions to protect against this vulnerability, and system administrators should monitor for compliance with these security updates. Security teams should also consider implementing additional monitoring for unusual calling patterns that might indicate exploitation attempts, particularly in enterprise environments where device security is paramount. The vulnerability demonstrates the importance of maintaining up-to-date security measures and highlights how convenience features can sometimes create security risks if not properly implemented with appropriate access controls.