CVE-2013-5154 in iOS
Summary
by MITRE
The Sandbox subsystem in Apple iOS before 7 determines the sandboxing requirement for a #! application on the basis of the script interpreter instead of the script, which allows attackers to bypass intended access restrictions via a crafted application.
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Analysis
by VulDB Data Team • 05/25/2021
The vulnerability identified as CVE-2013-5154 represents a critical sandboxing flaw within Apple iOS versions prior to 7.0, specifically affecting the system's sandbox subsystem that governs application security boundaries and access controls. This vulnerability stems from a fundamental misconfiguration in how the operating system evaluates sandboxing requirements for applications that utilize shebang (#!) directives. The sandboxing mechanism in iOS is designed to isolate applications from each other and from system resources, preventing unauthorized access and potential privilege escalation. However, this flaw creates a pathway for malicious actors to circumvent these security controls by exploiting the incorrect determination of sandboxing requirements.
The technical root cause of this vulnerability lies in the iOS sandbox subsystem's flawed logic for identifying which security context to apply to applications. When an application uses a shebang directive, the system should evaluate the script content itself to determine appropriate sandboxing requirements. Instead, the vulnerable implementation bases its decision on the script interpreter specified in the shebang line, creating a security gap that allows attackers to craft applications that bypass intended access restrictions. This misclassification occurs because the system fails to properly validate or consider the actual script content when determining sandboxing policies, effectively treating the interpreter as the determining factor rather than the script's true nature and requirements.
The operational impact of CVE-2013-5154 is significant, as it enables attackers to execute malicious code with elevated privileges or access restricted system resources that would normally be protected by iOS's sandboxing mechanisms. This vulnerability specifically affects applications that utilize shebang directives, which are commonly found in shell scripts and other interpreted programs. Attackers can exploit this flaw by creating crafted applications that appear to be safe scripts but contain malicious code that executes with broader permissions than intended. The vulnerability essentially allows for sandbox escape techniques that could lead to complete system compromise, data theft, or unauthorized access to protected system functions.
Security professionals should note that this vulnerability aligns with CWE-254, which addresses security weaknesses related to improper access control in software systems. The flaw demonstrates a classic case of inadequate privilege separation and improper input validation within the sandboxing subsystem. From an attacker's perspective, this vulnerability maps to several ATT&CK tactics including privilege escalation and defense evasion, as it allows adversaries to bypass security controls that would normally prevent unauthorized system access. The vulnerability also reflects broader concerns about sandbox implementation security, where the failure to properly validate application content leads to security boundary violations that can be exploited across multiple attack vectors.
Mitigation strategies for CVE-2013-5154 require immediate system updates to iOS 7.0 or later versions where Apple has addressed the sandboxing logic error. Organizations should implement comprehensive patch management procedures to ensure all iOS devices are updated promptly, as this vulnerability affects the core security architecture of the operating system. Additionally, security teams should conduct thorough application reviews to identify any shebang-based applications that might be vulnerable, though the primary defense remains the operating system update. Network monitoring solutions should also be configured to detect anomalous application behavior that might indicate exploitation attempts, as the vulnerability enables bypass of standard security controls that would normally prevent such activities. The fix implemented by Apple corrected the sandboxing evaluation logic to properly consider script content rather than interpreter specifications, restoring proper security boundaries within the iOS ecosystem.