CVE-2025-23403: SIMATIC IPC Privilege Escalation Vulnerability

CVE-2025-23403 Overview

Siemens disclosed CVE-2025-23403, a privilege escalation vulnerability affecting SIMATIC IPC DiagBase and SIMATIC IPC DiagMonitor. The affected products do not properly restrict user permissions on a registry key. An authenticated local attacker can leverage the misconfigured permissions to load vulnerable drivers into the system. This enables privilege escalation and can bypass endpoint protection and other host security controls. The weakness is tracked under [CWE-732: Incorrect Permission Assignment for Critical Resource]. Siemens published the coordinated disclosure in advisory SSA-369369.

Critical Impact
An authenticated local user can load vulnerable drivers to escalate privileges and bypass endpoint security controls on affected SIMATIC IPC systems.

Affected Products

SIMATIC IPC DiagBase (All versions)
SIMATIC IPC DiagMonitor (All versions)

Discovery Timeline

2025-02-11 - CVE-2025-23403 published to NVD
2026-06-17 - Last updated in NVD database

Technical Details for CVE-2025-23403

Vulnerability Analysis

CVE-2025-23403 is a registry permissions weakness classified under [CWE-732]. SIMATIC IPC DiagBase and SIMATIC IPC DiagMonitor install with a registry key that grants write access to non-privileged local users. Because the driver loading logic references configuration read from this registry key, a low-privileged user can influence which driver the software loads. An attacker exploits this by pointing the software at a known-vulnerable signed driver, then abusing the driver to execute code with kernel privileges. This pattern is commonly known as a Bring Your Own Vulnerable Driver (BYOVD) attack.

Root Cause

The root cause is an incorrect Access Control List (ACL) assigned to a registry key used by the DiagBase and DiagMonitor components. Standard users receive write permissions that should be restricted to administrators or SYSTEM. This violates the principle of least privilege for a security-sensitive configuration resource.

Attack Vector

Exploitation requires local access with a valid, low-privileged user account on the affected SIMATIC IPC host. The attacker modifies the vulnerable registry key to reference a driver path or configuration under attacker control. When the DiagBase or DiagMonitor service processes the modified value, it loads the attacker-selected driver. Successful exploitation results in code execution at elevated privilege and can neutralize host-based security agents. See the Siemens Security Advisory SSA-369369 for vendor details.

Detection Methods for CVE-2025-23403

Indicators of Compromise

Modifications to DiagBase or DiagMonitor registry keys performed by non-administrator accounts.
Unexpected driver load events referencing signed but known-vulnerable drivers on SIMATIC IPC hosts.
New service or kernel module creation shortly after registry writes to DiagBase or DiagMonitor paths.

Detection Strategies

Audit registry ACLs on DiagBase and DiagMonitor keys and flag any that grant write access to Users or Authenticated Users.
Monitor Windows Security event ID 4657 (registry value modification) for the affected keys and correlate with the invoking user context.
Enable Microsoft's Vulnerable Driver Blocklist and alert on blocked driver load attempts.

Monitoring Recommendations

Collect Sysmon Event ID 6 (Driver loaded) and correlate with driver signing hashes against the LOLDrivers project inventory.
Baseline expected driver load activity for SIMATIC IPC endpoints and alert on deviations.
Forward endpoint telemetry to a centralized data lake for cross-host correlation of BYOVD indicators.

How to Mitigate CVE-2025-23403

Immediate Actions Required

Review the Siemens Security Advisory SSA-369369 and apply vendor guidance for DiagBase and DiagMonitor installations.
Restrict interactive and remote logon rights on SIMATIC IPC hosts to trusted operators only.
Manually harden the ACL on the affected registry key to remove write permissions for non-administrative users.
Enable the Microsoft Vulnerable Driver Blocklist on all Windows-based SIMATIC IPC systems.

Patch Information

Siemens tracks remediation under advisory SSA-369369. At the time of the NVD entry, all versions of SIMATIC IPC DiagBase and SIMATIC IPC DiagMonitor are listed as affected. Consult the Siemens ProductCERT advisory for current fixed versions and mitigation instructions.

Workarounds

Apply defense-in-depth by isolating SIMATIC IPC systems on segmented industrial networks with restricted user access.
Enforce application allowlisting to prevent execution of unauthorized driver loader utilities.
Remove local administrative capabilities from operator accounts and require privileged access workstations for maintenance.

bash

# Configuration example: audit and tighten registry ACLs on Windows
# List current permissions on the suspected key (replace with vendor-identified path)
icacls "HKLM:\SOFTWARE\Siemens\DiagBase"

# Enable Microsoft Vulnerable Driver Blocklist via registry
reg add "HKLM\SYSTEM\CurrentControlSet\Control\CI\Config" /v VulnerableDriverBlocklistEnable /t REG_DWORD /d 1 /f