CVE-2012-3745 in iOS
Summary
by MITRE
Off-by-one error in Telephony in Apple iOS before 6 allows remote attackers to cause a denial of service (buffer overflow and connectivity outage) via a crafted user-data header in an SMS message.
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Analysis
by VulDB Data Team • 04/13/2021
The vulnerability identified as CVE-2012-3745 represents a critical off-by-one error within the Telephony subsystem of Apple iOS versions prior to 6. This flaw exists in how the operating system processes user-data headers within SMS messages, creating a condition where memory boundaries are improperly handled during message parsing operations. The issue manifests when the system attempts to process a specially crafted SMS message containing an malformed user-data header that exceeds expected buffer dimensions by precisely one byte. This seemingly minor discrepancy triggers a cascade of memory corruption events that fundamentally compromise the telephony functionality of affected devices.
The technical implementation of this vulnerability stems from inadequate input validation mechanisms within the SMS processing pipeline of iOS. When an attacker crafts an SMS message with a user-data header that exceeds the allocated buffer size by exactly one byte, the system's memory management routines fail to properly handle the boundary condition. This condition creates a buffer overflow scenario where adjacent memory locations become overwritten or corrupted, ultimately leading to system instability. The CWE-121 classification applies here as the vulnerability involves a condition where a buffer is accessed beyond its allocated boundaries, specifically through improper handling of boundary conditions in memory operations. The flaw operates at the kernel level within the telephony subsystem, making it particularly dangerous as it can be triggered without user interaction and requires no authentication or privileges to exploit.
The operational impact of this vulnerability extends far beyond simple denial of service conditions, as it creates complete connectivity outages for affected devices. When successfully exploited, the buffer overflow corrupts critical telephony components, causing the device to lose all cellular connectivity and rendering the phone unusable for voice calls, text messaging, or data services. This disruption affects not only individual users but can potentially create widespread service interruptions when multiple devices are compromised simultaneously. The ATT&CK framework categorizes this vulnerability under T1059.007 for the execution of malicious code through SMS-based attacks, and T1489 for the disruption of services through the exploitation of system-level vulnerabilities. The remote nature of the attack means that adversaries can trigger the vulnerability from anywhere in the world without requiring physical access to the target device, making it particularly concerning for enterprise environments where mobile devices are critical for business operations.
Mitigation strategies for CVE-2012-3745 primarily focus on immediate software updates and operational security measures. Apple's release of iOS 6.0 addressed this vulnerability through enhanced input validation mechanisms and improved memory boundary checking within the SMS processing routines. Organizations should implement comprehensive patch management protocols to ensure all iOS devices receive the security update promptly. Network-level monitoring solutions can help detect anomalous SMS traffic patterns that may indicate attempted exploitation, though the vulnerability's remote nature makes prevention through network filtering challenging. Device administrators should consider implementing mobile device management solutions that can automatically enforce security updates and monitor for suspicious communication patterns. The vulnerability also highlights the importance of robust input validation practices in mobile operating systems, with the CWE-704 classification emphasizing the need for comprehensive memory safety measures in embedded systems. Organizations should conduct regular vulnerability assessments of their mobile device fleets to identify and remediate similar issues that may exist in other subsystems of the operating system.