CVE-2018-9488 in Android
Summary
by MITRE
In the SELinux permissions of crash_dump.te, there is a permissions bypass due to a missing restriction. This could lead to a local escalation of privilege, with System privileges needed. User interaction is not needed for exploitation. Product: Android Versions: Android-8.0 Android-8.1 Android-9.0 Android ID: A-110107376.
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Analysis
by VulDB Data Team • 06/09/2024
The vulnerability identified as CVE-2018-9488 represents a critical security flaw in the Android operating system's security module, specifically within the SELinux policy configuration for crash dump functionality. This issue manifests in the crash_dump.te policy file where insufficient access controls have been implemented, creating a permissions bypass that allows unauthorized processes to escalate their privileges. The vulnerability affects multiple Android versions including 8.0, 8.1, and 9.0, indicating a widespread impact across the Android ecosystem. The flaw operates at the kernel level where SELinux, the security module responsible for enforcing mandatory access controls, fails to properly restrict access to crash dump related resources. This missing restriction creates a path for malicious actors to gain elevated privileges without requiring any user interaction, making the exploit particularly dangerous as it can be automated and executed silently.
The technical implementation of this vulnerability stems from improper SELinux policy definitions that govern how crash dump processes interact with system resources. When a crash dump is generated, the system should enforce strict access controls to prevent unauthorized access to sensitive data and system functions. However, the missing restriction in crash_dump.te allows processes to bypass these controls, potentially enabling attackers to access memory segments, system logs, or other sensitive crash-related information that should be restricted to system-level processes only. This flaw falls under the category of privilege escalation vulnerabilities and aligns with CWE-276, which addresses incorrect permissions for critical resources, and CWE-250, which covers execution with unnecessary privileges. The vulnerability operates at the system level, requiring only system privileges for exploitation, making it particularly concerning for devices where the attacker already has some level of access.
The operational impact of CVE-2018-9488 extends beyond simple privilege escalation, as it can potentially enable attackers to access sensitive system information, manipulate crash reporting mechanisms, and potentially gain deeper access to the device's core functionality. The local nature of the vulnerability means that an attacker does not need network access or user interaction to exploit it, which significantly increases the attack surface. This vulnerability can be leveraged to bypass security measures designed to protect against unauthorized access to system resources, potentially allowing attackers to extract sensitive data, modify system configurations, or even establish persistent access to the device. The attack vector operates through the manipulation of crash dump processes, which are typically used for debugging and system diagnostics but become security risks when access controls are improperly configured. According to ATT&CK framework, this vulnerability would map to privilege escalation techniques, specifically T1068 which covers 'Exploitation for Privilege Escalation' and T1059 which covers 'Command and Scripting Interpreter' as attackers might use the escalated privileges to execute malicious code.
Mitigation strategies for CVE-2018-9488 should focus on patch management and policy enforcement updates. Android device manufacturers and system administrators should prioritize applying the relevant security patches that address the missing restrictions in the crash_dump.te SELinux policy. The fix typically involves adding proper access controls and restrictions to prevent unauthorized processes from bypassing the intended security boundaries. Organizations should also implement monitoring systems to detect unusual crash dump activities that might indicate exploitation attempts. Additionally, security hardening measures including regular security audits of SELinux policies, implementation of least privilege principles, and comprehensive system logging should be enforced to detect and prevent unauthorized access attempts. The vulnerability highlights the importance of thorough security policy reviews and the critical need for proper access control implementations in security-critical components such as crash handling mechanisms. Regular security assessments of Android device security modules should include comprehensive SELinux policy reviews to identify and remediate similar configuration flaws that could lead to privilege escalation vulnerabilities.