CVE-2013-3951 in Watch
Summary
by MITRE
sys/openbsd/stack_protector.c in libc in Apple iOS 6.1.3 and Mac OS X 10.8.x does not properly parse the Apple strings employed in the user-space stack-cookie implementation, which allows local users to bypass cookie randomization by executing a program with a call-path beginning with the stack-guard= substring, as demonstrated by an iOS untethering attack or an attack against a setuid Mac OS X program.
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Analysis
by VulDB Data Team • 11/21/2024
The vulnerability described in CVE-2013-3951 represents a critical flaw in Apple's implementation of stack canary protection mechanisms within the libc library of iOS 6.1.3 and Mac OS X 10.8.x operating systems. This issue specifically targets the stack protector implementation that is designed to detect and prevent stack buffer overflow attacks by employing randomization techniques. The stack canary mechanism works by inserting a random value into the stack frame of functions, which is then checked before function return to ensure the stack has not been corrupted. When this protection is bypassed, it fundamentally undermines the security model designed to defend against such attacks.
The technical flaw stems from improper parsing of Apple-specific string formats used in the user-space stack-cookie implementation. The vulnerability allows local attackers to circumvent the randomization of stack canaries by crafting specific program execution paths that begin with the stack-guard= substring. This parsing error creates a predictable pattern that attackers can exploit to bypass the security checks that would normally prevent stack-based buffer overflows. The issue is particularly concerning because it affects the core system libraries that are fundamental to the operating system's security architecture.
The operational impact of this vulnerability is severe and multifaceted, particularly when considering the demonstrated attack vectors. The vulnerability enables successful iOS untethering attacks, which represent a significant compromise of mobile device security by allowing attackers to bypass the device's security protections without requiring a tethered reboot. Additionally, the flaw poses a serious threat to setuid programs on Mac OS X systems, where attackers could potentially escalate privileges through the bypassed stack protection mechanisms. This vulnerability essentially allows local users to execute arbitrary code with elevated privileges, making it a critical concern for system administrators and security professionals.
The vulnerability aligns with CWE-129, which describes improper validation of input, and relates to the broader category of stack-based buffer overflow protections that are fundamental to modern operating system security. From an ATT&CK framework perspective, this vulnerability maps to privilege escalation techniques and defense evasion methods, as it allows attackers to bypass system protections that would normally prevent malicious code execution. The attack requires local system access but provides a pathway for privilege escalation, making it particularly dangerous in environments where users might have legitimate access to system resources. Organizations should implement immediate mitigations including system updates, monitoring for suspicious execution patterns, and review of setuid program configurations to prevent exploitation of this vulnerability.