CVE-2025-25230

Executive Summary

CVE-2025-25230 is a Local Privilege Escalation (LPE) vulnerability in Omnissa Horizon Client for Windows. A malicious actor with local access to a system where the Horizon Client is installed can exploit this flaw to elevate their privileges, potentially gaining SYSTEM-level access. The vulnerability has a CVSS score of 7.8 (High), indicating significant impact on confidentiality, integrity, and availability. As of this report, no public exploit code, patch, or detailed technical analysis is available, but the local attack vector and low attack complexity make it a credible threat in post-compromise scenarios.

Supply Chain & Package Security

This vulnerability is not related to NPM, PyPI, Go, or Ruby packages. It is a proprietary Windows application (Omnissa Horizon Client) and does not involve open-source package supply chain risks.

CVSS Breakdown & Threat Level

• CVSS Score: 7.8 (High)
• Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
• Attack Vector (AV): Local – The attacker must have local access to the system.
• Attack Complexity (AC): Low – No special conditions or race conditions are required.
• Privileges Required (PR): Low – The attacker needs initial user-level access.
• User Interaction (UI): None – No user action is needed beyond the attacker’s own actions.
• Scope (S): Unchanged – The vulnerable component and the impacted component are the same.
• Confidentiality (C): High – Full read access to sensitive data.
• Integrity (I): High – Full write access to system files or registry.
• Availability (A): High – Potential to crash or deny service.

Threat Level: High. While the EPSS score is 0.0% (indicating low exploitation probability in the wild), the local nature and low complexity make it attractive for targeted attacks or as part of a multi-stage exploit chain.

Deep Dive & Mechanics

The vulnerability resides in the Omnissa Horizon Client for Windows, a remote desktop client used to connect to Horizon virtual desktops and applications. The exact mechanism is not publicly disclosed, but based on the CWE (CWE-269: Improper Privilege Management), it likely involves:

• Insecure Service Permissions: The Horizon Client may install a Windows service with weak permissions, allowing a low-privileged user to modify the service binary or configuration, leading to code execution as SYSTEM.
• DLL Hijacking: The client may load DLLs from an unsecured path (e.g., the user’s temporary directory), allowing an attacker to place a malicious DLL that gets loaded by a high-integrity process.
• Named Pipe Impersonation: The client may create a named pipe that can be accessed by low-privileged users, enabling impersonation of a higher-privileged token.

The attack requires local access, meaning the attacker must already have a foothold on the target system (e.g., via phishing, malware, or physical access). Once executed, the exploit grants SYSTEM privileges, allowing full control over the host.

Vulnerable vs. Patched Code

No patch or specific version information is available. The vulnerable code is likely in the core service or driver component of the Horizon Client. A patched version would:

• Enforce proper access control lists (ACLs) on service objects.
• Validate DLL loading paths using safe search order or digital signatures.
• Use secure impersonation tokens and restrict named pipe access.

Without official patch details, administrators should monitor Omnissa’s security advisories for updates.

Exploitation & Lab Setup

Red Team (Exploitation)

Since no public exploit code exists, a red team would need to reverse-engineer the Horizon Client to identify the vulnerable component. A typical approach:

1. Reconnaissance: Identify installed version and running processes (e.g., vmware-view.exe, wsnm.exe).
2. Service Enumeration: Check for weak service permissions using tools like accesschk or PowerUp.
3. DLL Hijacking: Monitor process creation with Procmon to find missing DLLs in the client’s search path.
4. Exploit Development: Write a proof-of-concept that either modifies a service binary or drops a malicious DLL.

Lab Setup:

• Target: Windows 10/11 with Omnissa Horizon Client installed (any version).
• Attacker: Local user account (non-admin).
• Tools: Process Monitor, PowerUp.ps1, accesschk, Visual Studio (for DLL compilation).

Example (Hypothetical DLL Hijacking):

// malicious_dll.c
#include <windows.h>
BOOL APIENTRY DllMain(HMODULE hModule, DWORD ul_reason_for_call, LPVOID lpReserved) {
    if (ul_reason_for_call == DLL_PROCESS_ATTACH) {
        system("cmd.exe /c net localgroup Administrators attacker /add");
    }
    return TRUE;
}

Compile as msvcp140.dll (or other missing DLL) and place in the client’s working directory.

Blue Team (Defense)

• Monitor for Anomalous Process Behavior: Use Sysmon to detect DLL load events from unusual paths (Event ID 7).
• Audit Service Permissions: Regularly check Horizon Client services with sc sdshow and ensure only trusted accounts have write access.
• Enable Windows Defender Exploit Guard: Use ASR rules to block DLL hijacking (e.g., block Win32 API calls from Office or other apps).
• Application Control: Use AppLocker or WDAC to allow only signed binaries and DLLs.

Indicators of Compromise (IOCs)

• File Hashes: Unknown (no public samples).
• Registry Keys: HKLM\SYSTEM\CurrentControlSet\Services\*Horizon* (modified permissions).
• Processes: vmware-view.exe or wsnm.exe spawning cmd.exe or powershell.exe as child processes.
• Network Connections: Unusual outbound connections from the Horizon Client process to non-standard ports.
• Event Logs:
  • Windows Security Log: Event ID 4672 (Special Logon) for SYSTEM account.
  • Sysmon Event ID 7 (DLL loaded from %TEMP% or %APPDATA%).

Detection Engineering

YARA Rule

rule CVE_2025_25230_Horizon_LPE {
    meta:
        description = "Detects potential exploit artifacts for CVE-2025-25230"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2025-25230"
    strings:
        $s1 = "Omnissa Horizon Client" wide ascii nocase
        $s2 = "wsnm.exe" wide ascii nocase
        $s3 = "vmware-view.exe" wide ascii nocase
        $s4 = "SYSTEM" wide ascii nocase
    condition:
        any of ($s1, $s2, $s3) and $s4
}

Sigma Rule

title: CVE-2025-25230 - Omnissa Horizon Client LPE Detection
id: 8a9b3c4d-5e6f-7a8b-9c0d-1e2f3a4b5c6d
status: experimental
description: Detects suspicious child processes spawned by Horizon Client processes
author: Valters IT
date: 2025-04-10
references:
    - https://nvd.nist.gov/vuln/detail/CVE-2025-25230
logsource:
    category: process_creation
    product: windows
detection:
    selection:
        ParentImage|endswith:
            - '\\vmware-view.exe'
            - '\\wsnm.exe'
        Image|endswith:
            - '\\cmd.exe'
            - '\\powershell.exe'
            - '\\wmic.exe'
    condition: selection
falsepositives:
    - Legitimate administrative tasks
level: high

Suricata Rule

alert tcp $HOME_NET any -> $EXTERNAL_NET any (msg:"CVE-2025-25230 - Potential Horizon Client LPE Outbound"; flow:to_server,established; content:"|0d 0a|"; depth:2; classtype:attempted-admin; sid:1000001; rev:1;)

Remediation & Mitigation

• Immediate: Restrict local access to systems running Horizon Client. Use the principle of least privilege for user accounts.
• Short-term: Monitor Omnissa’s security portal for patches. If no patch is available, consider removing the client from non-essential systems.
• Long-term: Implement application whitelisting (AppLocker) to prevent unauthorized executables. Enable Windows Defender Credential Guard to protect privileged tokens.
• Workaround: If the client is not required, uninstall it. If required, run it in a sandboxed environment (e.g., Windows Sandbox or a dedicated VM).

Valters IT – Securing your digital frontier.