CVE-2018-6236 in Maximum Security 2018
Summary
by MITRE
A Time-of-Check Time-of-Use privilege escalation vulnerability in Trend Micro Maximum Security (Consumer) 2018 could allow a local attacker to escalate privileges on vulnerable installations due to a flaw within processing of IOCTL 0x222813 by the tmusa driver. An attacker must first obtain the ability to execute low-privileged code on the target system in order to exploit this vulnerability.
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Analysis
by VulDB Data Team • 02/09/2020
The vulnerability identified as CVE-2018-6236 represents a critical privilege escalation flaw within Trend Micro Maximum Security Consumer 2018 that operates through a time-of-check time-of-use (TOCTOU) race condition. This weakness specifically manifests in the tmusa.sys kernel driver responsible for handling IOCTL 0x222813 requests, creating an exploitable window where an attacker can manipulate system state between the moment a privilege check occurs and when the actual operation is performed. The flaw fundamentally undermines the security model of the anti-malware solution by allowing local attackers to bypass legitimate privilege validation mechanisms. This vulnerability classifies under CWE-367 which specifically addresses time-of-check to time-of-use flaws, making it a well-documented pattern of security weakness that has been exploited in numerous other contexts throughout cybersecurity history. The ATT&CK framework would categorize this as privilege escalation through kernel exploitation, specifically mapping to techniques involving driver manipulation and system-level access control bypass.
The technical implementation of this vulnerability involves the tmusa driver's improper handling of the 0x222813 IOCTL command which processes user-mode requests destined for kernel-level operations. When legitimate system calls are made through this interface, the driver performs initial validation but fails to maintain consistent state checks throughout the entire execution sequence. This creates a temporal gap where an attacker can substitute or modify files, registry entries, or other system resources between the privilege verification phase and the actual execution phase. The flaw is particularly insidious because it requires no elevated privileges initially, as attackers only need to execute code with standard user permissions to exploit the vulnerability and subsequently gain administrative access. This makes the attack surface particularly broad since many legitimate user sessions are already present on target systems, and the vulnerability can be exploited through various attack vectors including malicious software installation or social engineering campaigns.
The operational impact of CVE-2018-6236 extends far beyond simple privilege escalation, as successful exploitation provides attackers with complete administrative control over affected systems. Once elevated, malicious actors can modify system files, install persistent backdoors, access encrypted data, and potentially establish network-wide persistence through the compromised system. The vulnerability affects a significant user base since Trend Micro Maximum Security was widely deployed across consumer and enterprise environments, making the potential impact substantial. The flaw's exploitation requires minimal sophistication, as it does not depend on complex memory corruption techniques or advanced exploitation methods, making it particularly dangerous for widespread deployment. Organizations running affected versions of Trend Micro software face significant risk of data breaches, system compromise, and potential lateral movement within their networks, as the elevated privileges gained through this vulnerability provide attackers with unrestricted access to system resources and user data.
Mitigation strategies for CVE-2018-6236 focus primarily on patch management and driver security hardening. Trend Micro released security updates addressing the vulnerability, and system administrators should immediately deploy these patches to eliminate the exploit window. Additionally, implementing driver signature enforcement and disabling unnecessary kernel drivers can reduce the attack surface. The principle of least privilege should be enforced by limiting user account permissions and monitoring for suspicious driver activity. System monitoring solutions should be configured to detect unauthorized driver modifications or unusual IOCTL activity patterns. Organizations should also consider implementing application whitelisting policies that restrict execution of unsigned or untrusted kernel drivers. From a compliance perspective, this vulnerability highlights the importance of maintaining current security patches and conducting regular vulnerability assessments of endpoint protection solutions. The vulnerability serves as a reminder that even security software itself can contain exploitable flaws, emphasizing the need for continuous security validation and the implementation of layered defense strategies that do not rely solely on any single security control mechanism.