CVE-2018-6597 in A30
Summary
by MITRE
The Alcatel A30 device with a build fingerprint of TCL/5046G/MICKEY6US:7.0/NRD90M/J63:user/release-keys contains a hidden privilege escalation capability to achieve command execution as the root user. They have made modifications that allow a user with physical access to the device to obtain a root shell via ADB. Modifying the read-only properties by an app as the system user creates a UNIX domain socket named factory_test that will execute commands as the root user by processes that have privilege to access it (as per the SELinux rules that the vendor controls).
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Analysis
by VulDB Data Team • 03/19/2020
The vulnerability described in CVE-2018-6597 represents a critical privilege escalation flaw in Alcatel A30 devices running Android 7.0. This issue stems from improper system configuration that allows unauthorized users with physical access to gain root-level privileges through the Android Debug Bridge (ADB) interface. The vulnerability specifically affects devices with the build fingerprint TCL/5046G/MICKEY6US:7.0/NRD90M/J63:user/release-keys, indicating a targeted flaw within this particular device model and firmware version. The security compromise occurs through modifications that enable command execution as the root user, fundamentally undermining the device's security model and potentially exposing sensitive data and system resources to malicious actors.
The technical implementation of this vulnerability involves a sophisticated manipulation of the Android system's security controls through a hidden mechanism that modifies read-only properties. When an application operates with system user privileges, it can create a UNIX domain socket named factory_test that serves as a backdoor for command execution. This socket operates under specific SELinux rules that the vendor controls, allowing processes with appropriate privileges to execute commands as the root user. The vulnerability exploits the lack of proper access controls and the trust placed in system-level processes, creating a persistent entry point that bypasses normal security boundaries. The mechanism relies on the device's ADB functionality being enabled and accessible to unauthorized users, which represents a significant configuration weakness in the device's security architecture.
The operational impact of this vulnerability extends far beyond simple privilege escalation, as it provides attackers with complete control over the device's operating system and all its resources. Once an attacker gains access through this mechanism, they can execute arbitrary commands, modify system files, install malicious applications, and potentially exfiltrate sensitive data from the device. The vulnerability is particularly concerning because it requires only physical access to the device, making it exploitable in scenarios where the device is left unattended or in environments where physical security is compromised. The attack surface is further expanded by the fact that the vulnerability can be triggered through legitimate system processes, making detection and prevention more challenging for security monitoring systems.
Mitigation strategies for this vulnerability must address both the immediate security flaw and the underlying configuration issues that enable exploitation. Organizations should ensure that ADB is disabled on production devices and that physical access controls are implemented to prevent unauthorized users from gaining access to the device. The system configuration modifications that create the factory_test socket must be reviewed and secured to prevent unauthorized creation of privileged communication channels. Security professionals should implement comprehensive monitoring for unauthorized socket creation and privilege escalation attempts, leveraging SELinux policies to enforce stricter access controls. Additionally, device manufacturers should conduct thorough security reviews of their system configurations and ensure that all read-only properties are properly enforced to prevent modification by unauthorized processes. This vulnerability aligns with CWE-276, which addresses improper privileges, and represents a significant concern for the ATT&CK framework's privilege escalation techniques, particularly those involving system-level access and command execution.