CVE-2017-0475 in Android
Summary
by MITRE
An elevation of privilege vulnerability in the recovery verifier could enable a local malicious application to execute arbitrary code within the context of the kernel. This issue is rated as Critical due to the possibility of a local permanent device compromise, which may require reflashing the operating system to repair the device. Product: Android. Versions: 4.4.4, 5.0.2, 5.1.1, 6.0, 6.0.1, 7.0, 7.1.1. Android ID: A-31914369.
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Analysis
by VulDB Data Team • 03/08/2017
The vulnerability identified as CVE-2017-0475 represents a critical elevation of privilege flaw within the Android recovery verifier component, specifically targeting versions ranging from 4.4.4 through 7.1.1. This weakness resides in the system's ability to verify recovery images during the boot process, creating a pathway for malicious applications to escalate their privileges from user-level to kernel-level execution. The recovery verifier serves as a security mechanism designed to ensure that only trusted recovery images can be loaded, making this vulnerability particularly dangerous as it undermines the fundamental security boundaries of the Android operating system. The flaw allows a local attacker with a malicious application installed on the device to exploit the verification process and gain unauthorized kernel access.
The technical implementation of this vulnerability stems from improper validation within the recovery verification logic, where insufficient input sanitization and inadequate access controls permit malicious code to bypass the normal security checks. When an application attempts to load a recovery image, the system should validate the image integrity and authenticity before allowing execution. However, the vulnerability creates a condition where crafted malicious recovery images can pass verification, ultimately enabling code execution with kernel privileges. This type of flaw maps directly to CWE-284 Access Control Issues, specifically in the context of privilege escalation where insufficient controls allow unauthorized elevation of privileges. The vulnerability manifests as a direct consequence of the recovery verifier's failure to properly validate recovery image signatures or integrity checks, which should normally be enforced by the system's secure boot mechanisms.
The operational impact of CVE-2017-0475 extends beyond simple privilege escalation, as it provides attackers with complete control over the device's kernel space operations. This level of access enables persistent rootkit installation, complete system compromise, and potential data exfiltration without detection. The vulnerability's critical nature is underscored by the fact that exploitation can result in permanent device compromise requiring full system reinstallation or reflashing. Attackers could leverage this vulnerability to install persistent backdoors, modify system binaries, or extract sensitive information from the device's memory and storage. The local nature of the attack means that no network connectivity or external exploitation is required, making it particularly dangerous as it only requires the victim to have a malicious application installed on their device. This aligns with ATT&CK technique T1068 Privilege Escalation, specifically focusing on local privilege escalation through kernel-level vulnerabilities.
Mitigation strategies for this vulnerability primarily involve immediate system updates and patches provided by Google and device manufacturers, as the flaw exists within core Android system components that require official security updates to resolve. Organizations and users should prioritize applying the latest security patches to all affected Android versions, particularly those running versions 4.4.4 through 7.1.1. Device manufacturers should ensure timely delivery of security updates through their over-the-air update mechanisms. Additional defensive measures include implementing application whitelisting policies to prevent installation of untrusted applications, maintaining regular system backups, and monitoring for unusual system behavior that might indicate compromise. The vulnerability highlights the importance of secure boot mechanisms and proper access control enforcement in system recovery processes, emphasizing the need for robust verification procedures that cannot be bypassed by local malicious applications. Security professionals should also consider implementing endpoint detection and response solutions to monitor for potential exploitation attempts of similar kernel-level vulnerabilities.