CVE-2023-38817 Overview
CVE-2023-38817 is a local privilege escalation vulnerability in Inspect Element Ltd Echo.ac version 5.2.1.0, an anti-cheat tool. The flaw resides in the echo_driver.sys kernel driver component. A local attacker with low privileges can submit a crafted command through an IOCTL to escalate privileges. Public technical analysis indicates the driver exposed functionality allowing user-mode applications to execute code as NT AUTHORITY\SYSTEM. The vendor states this capability was "deactivated by Microsoft itself," disputing exploitability on patched systems. The vulnerability is classified under [CWE-269] Improper Privilege Management.
Critical Impact
A local low-privileged user can abuse the echo_driver.sys kernel driver to execute code as NT AUTHORITY\SYSTEM, granting complete control over the affected host.
Affected Products
- Inspect Element Ltd Echo.ac anti-cheat tool version 5.2.1.0
- Systems with the echo_driver.sys kernel driver loaded
- Windows hosts running games or applications bundled with Echo.ac
Discovery Timeline
- 2023-10-11 - CVE-2023-38817 published to the National Vulnerability Database
- 2024-11-21 - Last updated in NVD database
Technical Details for CVE-2023-38817
Vulnerability Analysis
The vulnerability exists in echo_driver.sys, a kernel-mode component shipped with the Echo.ac anti-cheat product. Kernel drivers run at the highest privilege level on Windows. They must validate every request issued from user mode through I/O Control (IOCTL) interfaces. The Echo.ac driver accepts a crafted IOCTL request from a local process and performs a privileged action on its behalf. According to the public write-up, the driver exposes functionality that allows a caller to obtain NT AUTHORITY\SYSTEM code execution. The flaw is an instance of [CWE-269] Improper Privilege Management, where a lower-privileged caller gains capabilities reserved for SYSTEM.
Root Cause
The root cause is missing or insufficient access control on the driver's IOCTL handler. The driver does not adequately restrict which callers may issue privileged commands. It also fails to constrain the privileged operations it performs on behalf of an arbitrary user-mode process. This pattern is common in gaming anti-cheat and system utility drivers that expose powerful primitives without binding them to the originating process context.
Attack Vector
Exploitation requires local access and a low-privileged user account. An attacker opens a handle to the driver's device object and issues the crafted IOCTL with attacker-controlled parameters. The driver processes the request in kernel mode and grants elevated execution to the calling process. No user interaction is required after the attacker has code execution as a standard user. The vendor disputes practical exploitation, asserting that Microsoft has deactivated the abused primitive.
No verified public proof-of-concept code is included with this advisory. See the IOCTL Fail Security Writeup for technical details on the driver interface.
Detection Methods for CVE-2023-38817
Indicators of Compromise
- Presence of echo_driver.sys at version 5.2.1.0 on hosts not running the associated game or application
- Unexpected loading of echo_driver.sys by non-Echo.ac parent processes
- Local processes obtaining NT AUTHORITY\SYSTEM tokens shortly after opening a handle to the Echo driver device object
Detection Strategies
- Inventory all signed third-party kernel drivers and flag echo_driver.sys for review on systems where Echo.ac is not required
- Monitor CreateFile calls targeting the Echo driver device path followed by DeviceIoControl calls from non-game processes
- Alert on token manipulation or process integrity level changes following interaction with vulnerable drivers
Monitoring Recommendations
- Enable Windows kernel driver load auditing (Event ID 6) and forward events to a centralized logging platform
- Track child processes spawned with SYSTEM integrity from medium-integrity parents
- Correlate driver IOCTL activity with subsequent privilege escalation and credential access behaviors
How to Mitigate CVE-2023-38817
Immediate Actions Required
- Identify and uninstall Echo.ac version 5.2.1.0 from systems that no longer require the anti-cheat tool
- Apply Microsoft's Vulnerable Driver Blocklist on Windows endpoints to prevent loading of known-vulnerable drivers
- Restrict local user access on shared and high-value workstations to reduce exposure to local privilege escalation
Patch Information
No vendor patch advisory is referenced in the CVE record. The vendor's position is that the abused capability was "deactivated by Microsoft itself," implying mitigation at the operating system level rather than through a software update. Administrators should confirm Microsoft's Vulnerable Driver Blocklist is enabled and updated on all managed endpoints.
Workarounds
- Enable the Microsoft Vulnerable Driver Blocklist through Windows Security > Device security > Core isolation > Microsoft Vulnerable Driver Blocklist
- Enforce Hypervisor-Protected Code Integrity (HVCI) to block unsigned or revoked drivers from loading
- Remove echo_driver.sys from systems where the Echo.ac product is not actively required
# Verify Microsoft Vulnerable Driver Blocklist status (PowerShell, run as Administrator)
Get-ItemProperty -Path 'HKLM:\SYSTEM\CurrentControlSet\Control\CI\Config' -Name 'VulnerableDriverBlocklistEnable'
# Enable the blocklist if disabled
Set-ItemProperty -Path 'HKLM:\SYSTEM\CurrentControlSet\Control\CI\Config' -Name 'VulnerableDriverBlocklistEnable' -Value 1
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
