CVE-2023-38817: Echo Anti Cheat Privilege Escalation Flaw

CVE-2023-38817 Overview

CVE-2023-38817 is a local privilege escalation vulnerability in Inspect Element Ltd's Echo.ac anti-cheat tool version 5.2.1.0. The vulnerability exists in the echo_driver.sys kernel driver component, which allows a local attacker to gain elevated privileges by sending a crafted command to the driver. Successful exploitation enables user-mode applications to execute code with NT AUTHORITY\SYSTEM privileges, representing a complete compromise of local system security.

Critical Impact

Local attackers can escalate privileges to NT AUTHORITY\SYSTEM through the vulnerable echo_driver.sys kernel driver, enabling complete system compromise.

Affected Products

• Echo Anti Cheat Tool version 5.2.1.0
• echo_driver.sys kernel driver component

Discovery Timeline

• 2023-10-11 - CVE-2023-38817 published to NVD
• 2024-11-21 - Last updated in NVD database

Technical Details for CVE-2023-38817

Vulnerability Analysis

This vulnerability represents a driver vulnerability in the Echo anti-cheat tool's kernel-mode driver (echo_driver.sys). The flaw stems from improper privilege management (CWE-269), where the driver fails to adequately validate or restrict commands received from user-mode applications. This architectural weakness allows unprivileged local users to interact with the driver in ways that enable arbitrary code execution at the kernel level.

The attack requires local access to the system where Echo.ac is installed. Once exploited, an attacker gains NT AUTHORITY\SYSTEM privileges, which provides complete control over the affected Windows system. This includes the ability to install persistent malware, access all user data, disable security controls, and potentially pivot to other systems on the network.

It's noteworthy that the vendor (Inspect Element Ltd) has stated that the reported capability for user-mode applications to execute code as NT AUTHORITY\SYSTEM was "deactivated by Microsoft itself," suggesting potential mitigations at the operating system level.

Root Cause

The root cause is improper privilege management (CWE-269) in the echo_driver.sys kernel driver. The driver exposes functionality that can be abused by local attackers to escalate privileges. Kernel drivers operate at the highest privilege level in Windows, and any security flaw in their implementation can lead to complete system compromise. The driver appears to insufficiently validate commands or requests from user-mode applications, allowing crafted inputs to trigger privileged operations.

Attack Vector

The attack vector is local, requiring the attacker to have existing access to the target system. The exploitation flow involves:

1. The attacker identifies a system running Echo.ac v.5.2.1.0 with the vulnerable echo_driver.sys driver loaded
2. The attacker crafts a malicious command specifically designed to exploit the driver's improper privilege management
3. The crafted command is sent to the driver through its exposed interface (likely an IOCTL handler)
4. The driver processes the command without proper validation, leading to privilege escalation
5. The attacker's code executes with NT AUTHORITY\SYSTEM privileges

For detailed technical analysis of the exploitation technique, refer to the IOCTL Fail Writeup.

Detection Methods for CVE-2023-38817

Indicators of Compromise

• Presence of echo_driver.sys version 5.2.1.0 loaded in the system's kernel drivers
• Unexpected processes running with NT AUTHORITY\SYSTEM privileges that originated from user context
• Suspicious IOCTL communications with the Echo.ac driver from non-standard processes
• Unusual privilege escalation events in Windows Security logs

Detection Strategies

• Monitor for process creation events where the parent process has lower privileges than the child process
• Implement driver integrity monitoring to detect loading of known vulnerable driver versions
• Use endpoint detection and response (EDR) solutions like SentinelOne to detect suspicious kernel-mode activity
• Configure Windows Event Log auditing for privilege escalation events (Event ID 4673, 4674)

Monitoring Recommendations

• Enable detailed auditing of kernel driver loading events through Windows Security Policy
• Monitor for anomalous IOCTL patterns targeting anti-cheat drivers
• Implement behavioral analysis to detect unusual SYSTEM privilege acquisitions
• Review process lineage for suspicious privilege transitions from standard user to SYSTEM

How to Mitigate CVE-2023-38817

Immediate Actions Required

• Audit systems for the presence of Echo.ac v.5.2.1.0 and the vulnerable echo_driver.sys component
• Consider removing or disabling Echo.ac until a patched version is confirmed available
• Restrict local access to systems running the vulnerable software to trusted users only
• Implement application whitelisting to prevent unauthorized executables from interacting with the driver

Patch Information

There is no vendor advisory or confirmed patch information available in the CVE data. The vendor has indicated that Microsoft has deactivated the vulnerable functionality at the operating system level. Users should contact Inspect Element Ltd directly for the latest security guidance and updated software versions. Monitor official vendor channels for security updates.

Workarounds

• Unload or disable the echo_driver.sys driver if the anti-cheat functionality is not critical to operations
• Implement strict access controls limiting which users can log in locally to affected systems
• Use Windows Defender Application Control (WDAC) or similar technologies to restrict driver loading
• Deploy SentinelOne endpoint protection to monitor and block exploitation attempts targeting kernel drivers

# Check for vulnerable driver presence
sc query echo_driver
driverquery /v | findstr /i "echo"

# Disable the driver (requires administrative privileges)
sc config echo_driver start= disabled
sc stop echo_driver