CVE-2008-4228 in iPhone OS
Summary
by MITRE
The Passcode Lock feature in Apple iPhone OS 1.0 through 2.1 and iPhone OS for iPod touch 1.1 through 2.1 allows physically proximate attackers to leverage the emergency-call ability of locked devices to make a phone call to an arbitrary number.
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Analysis
by VulDB Data Team • 08/29/2019
The vulnerability described in CVE-2008-4228 represents a critical security flaw in Apple's iPhone OS and iPod touch operating systems version 1.0 through 2.1. This issue specifically affects the passcode lock mechanism that was designed to protect user devices from unauthorized access. The flaw enables attackers who are physically proximate to a locked device to bypass the standard security measures through a seemingly legitimate emergency call function. This vulnerability fundamentally undermines the core security principle of device authentication and access control that users rely upon to protect their personal data and communications.
The technical implementation of this vulnerability stems from how the operating system handles emergency call functionality when a device is locked. In the affected versions, the emergency call feature was not properly restricted to prevent arbitrary dialing when the device was secured with a passcode. This design flaw allows an attacker to access the emergency call interface directly from the locked screen, bypassing the normal passcode entry process. The system fails to validate that the emergency call function should be restricted to the legitimate emergency services, instead permitting unrestricted access to the phone dialer from the locked state. This represents a failure in input validation and access control mechanisms that should have prevented unauthorized use of the device's communication capabilities.
The operational impact of this vulnerability is significant for users who may be in physical proximity to a device they believe to be secure. Attackers can exploit this weakness to make unauthorized phone calls to any number, potentially leading to financial loss through premium rate services, privacy violations through communication interception, or social engineering attacks. The vulnerability also creates a vector for malicious actors to use stolen or lost devices for unauthorized communications without the need for sophisticated attack techniques. This threat is particularly concerning because it requires minimal skill and access - simply being physically near the device is sufficient to exploit the flaw. The vulnerability essentially renders the passcode lock ineffective as a security control, undermining the trust users place in their device's security features.
Mitigation strategies for this vulnerability involve immediate software updates from Apple to address the flawed implementation of the emergency call feature. Users should upgrade to versions of the operating system that properly restrict emergency call functionality when devices are locked. The fix typically involves implementing proper access controls that ensure the emergency call interface cannot be used to make arbitrary phone calls without proper authentication. Organizations should also consider implementing additional security measures such as remote wipe capabilities and device management solutions to protect against unauthorized use of compromised devices. This vulnerability highlights the importance of proper security testing and validation of emergency features in mobile operating systems, particularly those that interface with core communication functions. The issue demonstrates how seemingly benign features can become security risks when not properly integrated with the device's overall security architecture, emphasizing the need for comprehensive security reviews of all system components.
This vulnerability aligns with several common weakness enumerations including CWE-284, which addresses improper access control, and CWE-310, which covers cryptographic weaknesses in access control systems. From an attack framework perspective, this issue maps to ATT&CK technique T1217 which involves the use of system binary to bypass security controls. The flaw represents a classic example of insufficient input validation where the system fails to properly authenticate users before allowing access to sensitive functions. The security implications extend beyond the immediate unauthorized calling capability to encompass broader concerns about device integrity and user privacy protection in mobile environments.