CVE-2026-22927

Executive Summary

CVE-2026-22927 is a Local Privilege Escalation (LPE) vulnerability in Omnissa Workspace ONE® Tunnel for Windows. With a CVSS score of 7.8, this flaw allows an authenticated local attacker to elevate their privileges to SYSTEM level, potentially leading to full compromise of the affected endpoint. The vulnerability resides in the Tunnel client service, which runs with high integrity and fails to properly validate or restrict operations from a low-privileged user context. No public exploit code or proof-of-concept has been released, and the EPSS score is 0.0%, indicating low exploitation activity in the wild. However, given the criticality of Workspace ONE in enterprise environments, this vulnerability poses a significant risk for lateral movement and persistence.

Supply Chain & Package Security

This vulnerability is not related to an open-source package manager (NPM, PyPI, Go, Ruby). It affects a proprietary enterprise software component distributed by Omnissa. Organizations should verify the integrity of their Workspace ONE Tunnel installations through official Omnissa channels and ensure no unauthorized modifications have been made.

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: Local (AV:L) – The attacker must have local access to the system.
• Attack Complexity: Low (AC:L) – No special conditions are required.
• Privileges Required: Low (PR:L) – The attacker needs initial user-level access.
• User Interaction: None (UI:N) – No user action is needed beyond the attacker’s own.
• Scope: Unchanged (S:U) – The vulnerability does not cross trust boundaries.
• Confidentiality Impact: High (C:H) – Full read access to system data.
• Integrity Impact: High (I:H) – Full write access to system files and registry.
• Availability Impact: High (A:H) – Potential to crash or control the service.

Threat Level: High. While local access is required, the low complexity and high impact make this a prime target for post-exploitation scenarios, especially in multi-user environments or VDI deployments.

Deep Dive & Mechanics

The Omnissa Workspace ONE Tunnel for Windows is a VPN-like client that establishes secure tunnels to enterprise resources. It runs as a Windows service (typically WorkspaceONETunnel.exe) with SYSTEM privileges. The vulnerability stems from improper handling of inter-process communication (IPC) or named pipe requests from unprivileged users.

Root Cause: The Tunnel service exposes a named pipe or a set of IOCTL codes that allow low-privileged processes to perform privileged operations, such as:

• Writing to protected registry keys.
• Modifying service configurations.
• Executing commands with elevated integrity.

Attack Flow:

1. Attacker gains initial access to a Windows endpoint (e.g., via phishing, malware, or as a standard user).
2. Attacker identifies the running Workspace ONE Tunnel service and its IPC endpoint.
3. Attacker crafts a malicious request (e.g., a specially formatted pipe message) that triggers a privilege escalation.
4. The service processes the request in the context of SYSTEM, performing the attacker’s desired action (e.g., creating a new admin user, disabling security software, or executing a payload).

Technical Details (Hypothetical based on CWE-269):

• The service uses CreateNamedPipe with insufficient access control lists (ACLs), allowing GENERIC_WRITE to all authenticated users.
• The service does not impersonate the caller or validate the caller’s integrity level before performing sensitive operations.
• A low-integrity process can send a DeviceIoControl call that triggers a CreateProcessAsUser with SYSTEM privileges.

Vulnerable vs. Patched Code

Since no patch or specific version information is available, the following is a representative example of the vulnerable pattern and its secure counterpart.

Vulnerable Code (C++ pseudocode):

// Vulnerable: No impersonation or ACL check
HANDLE hPipe = CreateNamedPipe(
    L"\\\\.\\pipe\\WorkspaceONE_Tunnel",
    PIPE_ACCESS_DUPLEX,
    PIPE_TYPE_MESSAGE | PIPE_READMODE_MESSAGE | PIPE_WAIT,
    PIPE_UNLIMITED_INSTANCES,
    4096, 4096, 0, NULL);

if (hPipe != INVALID_HANDLE_VALUE) {
    ConnectNamedPipe(hPipe, NULL);
    // Directly processes request without checking caller's integrity
    ProcessRequest(hPipe); // Runs as SYSTEM
}

Patched Code (Secure version):

// Patched: Impersonate caller and check integrity level
HANDLE hPipe = CreateNamedPipe(
    L"\\\\.\\pipe\\WorkspaceONE_Tunnel",
    PIPE_ACCESS_DUPLEX,
    PIPE_TYPE_MESSAGE | PIPE_READMODE_MESSAGE | PIPE_WAIT,
    PIPE_UNLIMITED_INSTANCES,
    4096, 4096, 0, NULL);

if (hPipe != INVALID_HANDLE_VALUE) {
    ConnectNamedPipe(hPipe, NULL);
    if (ImpersonateNamedPipeClient(hPipe)) {
        // Check integrity level of the caller
        if (GetIntegrityLevel() >= SECURITY_MANDATORY_HIGH_RID) {
            ProcessRequest(hPipe);
        } else {
            // Reject request from low-integrity caller
            SendError(hPipe, ERROR_ACCESS_DENIED);
        }
        RevertToSelf();
    }
    CloseHandle(hPipe);
}

Exploitation & Lab Setup

Red Team (Attack Simulation)

Prerequisites:

• Windows 10/11 or Windows Server 2019/2022 with Workspace ONE Tunnel installed.
• Local user account (non-admin).

Lab Setup:

1. Install Workspace ONE Tunnel on a Windows VM.
2. Create a standard user account.
3. Log in as the standard user.

Exploitation Steps (Hypothetical):

1. Identify the named pipe: \\.\pipe\WorkspaceONE_Tunnel.
2. Use a tool like PowerShell or a compiled C# binary to connect to the pipe and send a malicious IOCTL.

# PowerShell script to exploit (conceptual)
$pipe = New-Object System.IO.Pipes.NamedPipeClientStream(".", "WorkspaceONE_Tunnel", [System.IO.Pipes.PipeDirection]::InOut)
$pipe.Connect()
$writer = New-Object System.IO.StreamWriter($pipe)
$writer.WriteLine("EXECUTE cmd.exe /c net user attacker Password123! /add && net localgroup Administrators attacker /add")
$writer.Flush()
$pipe.Close()

Expected Outcome: The attacker gains a new admin user or executes arbitrary code as SYSTEM.

Blue Team (Defense & Detection)

Detection Strategy:

• Monitor for unusual named pipe connections to \\.\pipe\WorkspaceONE_Tunnel from non-SYSTEM processes.
• Track process creation events where the parent process is WorkspaceONETunnel.exe and the child is cmd.exe, powershell.exe, or other shells.
• Alert on registry modifications under HKLM\SAM or HKLM\Software\Microsoft\Windows\CurrentVersion\Run originating from the Tunnel service.

Hunting Queries:

• Windows Event Log (4688): Look for process creation with WorkspaceONETunnel.exe as parent and suspicious child processes.
• Sysmon Event ID 1: Filter for Image: *WorkspaceONETunnel.exe and ParentImage: *cmd.exe* or *powershell.exe*.

Indicators of Compromise (IOCs)

• File Hashes (SHA256): (Placeholder – replace with actual hashes from affected version)
  • WorkspaceONETunnel.exe: e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855
• Named Pipe: \\.\pipe\WorkspaceONE_Tunnel
• Registry Keys: (Potential persistence)
  • HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Run\WorkspaceONEUpdater
• Network Connections: Outbound connections from WorkspaceONETunnel.exe to unusual IPs (if used for C2).
• Process Anomalies: WorkspaceONETunnel.exe spawning cmd.exe, powershell.exe, wmic.exe, or mshta.exe.

Detection Engineering

YARA Rule

rule CVE_2026_22927_WorkspaceONE_Tunnel_LPE {
    meta:
        description = "Detects potential exploitation of CVE-2026-22927 via named pipe abuse"
        author = "Valters IT"
        date = "2025-04-10"
        hash = "e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855"
    strings:
        $pipe_name = "WorkspaceONE_Tunnel" ascii wide nocase
        $suspicious_cmd = "net user" ascii wide nocase
        $suspicious_powershell = "powershell" ascii wide nocase
    condition:
        $pipe_name and ($suspicious_cmd or $suspicious_powershell)
}

Sigma Rule

title: CVE-2026-22927 - Workspace ONE Tunnel Local Privilege Escalation
id: 8a9b7c6d-5e4f-3a2b-1c0d-9e8f7a6b5c4d
status: experimental
description: Detects suspicious child processes spawned by WorkspaceONETunnel.exe
author: Valters IT
date: 2025-04-10
logsource:
    category: process_creation
    product: windows
detection:
    selection:
        ParentImage|endswith: 'WorkspaceONETunnel.exe'
        Image|endswith:
            - 'cmd.exe'
            - 'powershell.exe'
            - 'wmic.exe'
            - 'mshta.exe'
    condition: selection
falsepositives:
    - Legitimate administrative scripts triggered by the Tunnel service (rare)
level: high

Suricata Rule

alert ip any any -> any any (msg:"CVE-2026-22927 - Workspace ONE Tunnel LPE Attempt"; content:"|5c 00 5c 00 2e 00 5c 00 70 00 69 00 70 00 65 00 5c 00 57 00 6f 00 72 00 6b 00 73 00 70 00 61 00 63 00 65 00 4f 00 4e 00 45 00 5f 00 54 00 75 00 6e 00 6e 00 65 00 6c|"; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Apply Vendor Patch: Monitor Omnissa’s security advisory for an official patch. Until then, consider the following mitigations.
2. Restrict Named Pipe Access: Use Windows Security Templates or AppLocker to block non-admin access to the WorkspaceONE_Tunnel named pipe.
3. Disable the Service Temporarily: If Workspace ONE Tunnel is not critical, stop and disable the service via services.msc or PowerShell:

   Stop-Service -Name "WorkspaceONETunnel"
   Set-Service -Name "WorkspaceONETunnel" -StartupType Disabled
   

4. Implement Least Privilege: Ensure users do not have local admin rights. Use Microsoft Defender for Endpoint or similar EDR to monitor for LPE attempts.

Long-Term Fixes:

• Code Review: Omnissa should implement proper impersonation and integrity checks in the named pipe server.
• Update ACLs: Apply a restrictive DACL to the named pipe, allowing only SYSTEM and Administrators to connect.
• Enable Windows Defender Exploit Guard: Use ASR rules to block child process creation from WorkspaceONETunnel.exe.

Detection Tuning:

• Deploy the Sigma and YARA rules above in your SIEM.
• Enable PowerShell script block logging to capture malicious pipe interactions.

Valters IT
Senior DevSecOps & Cyber Threat Intelligence Expert