CVE-2023-32179

Executive Summary

CVE-2023-32179 is a local privilege escalation (LPE) vulnerability in VIPRE Antivirus Plus, specifically within the FPQuarTransfer method. The flaw allows a low-privileged attacker to abuse a link following (symlink) weakness to delete arbitrary files on the system. By leveraging this arbitrary file delete capability, an attacker can escalate privileges to SYSTEM and execute arbitrary code. The vulnerability was reported through the Zero Day Initiative (ZDI-CAN-19397) and carries a CVSS score of 7.8 (High). No public proof-of-concept (PoC) or exploit code has been released, and the patch status remains unknown.

Supply Chain & Package Security

This vulnerability is not related to any open-source package ecosystem (NPM, PyPI, Go, Ruby). It affects a proprietary Windows antivirus product (VIPRE Antivirus Plus). No supply chain implications are present.

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 are required beyond standard low-privileged code execution.
• Privileges Required (PR): Low – The attacker needs initial low-privileged access.
• User Interaction (UI): None – No user action is needed.
• Scope (S): Unchanged – The vulnerable component and the impacted component are the same.
• Confidentiality (C): High – Full system compromise can lead to data exposure.
• Integrity (I): High – Arbitrary file deletion and code execution can modify system state.
• Availability (A): High – Denial of service is possible via critical file deletion.

Threat Level: High. The vulnerability is locally exploitable with low privileges and no user interaction, making it a serious risk for enterprise environments where users have limited accounts.

Deep Dive & Mechanics

The vulnerability resides in the FPQuarTransfer method of VIPRE Antivirus Plus. This method is likely part of the quarantine management functionality, which handles moving or deleting quarantined files. The flaw is a classic link following vulnerability (CWE-59: Improper Link Resolution Before File Access).

Mechanism:

1. A low-privileged user executes code on the target system.
2. The attacker creates a symbolic link (symlink) pointing from a location that the FPQuarTransfer method will write to or delete, to a critical system file (e.g., C:\Windows\System32\config\SAM or a driver file).
3. When the FPQuarTransfer method performs a file operation (likely a delete or move) on the attacker-controlled path, it follows the symlink and performs the operation on the target file.
4. By deleting a critical system file (e.g., a security database or a privileged executable), the attacker can cause a denial of service or, more commonly, leverage the deletion to bypass security controls and escalate privileges to SYSTEM.

The vulnerability is triggered without user interaction, as the FPQuarTransfer method runs in the context of a high-privileged service (SYSTEM). The attacker only needs to create the symlink and wait for the service to act on it.

Vulnerable vs. Patched Code

No official patch details are available. However, based on the vulnerability type, the fix would involve:

• Vulnerable Code (Conceptual):

  // Pseudocode for vulnerable FPQuarTransfer
  void FPQuarTransfer::DeleteQuarantinedFile(const std::wstring& userPath) {
      // No check for symbolic links
      if (DeleteFileW(userPath.c_str())) {
          // Success
      }
  }
  

• Patched Code (Conceptual):

  // Pseudocode for patched FPQuarTransfer
  void FPQuarTransfer::DeleteQuarantinedFile(const std::wstring& userPath) {
      // Resolve the final target and check if it's within allowed directories
      HANDLE hFile = CreateFileW(userPath.c_str(), DELETE, FILE_SHARE_READ, NULL, OPEN_EXISTING, FILE_FLAG_OPEN_REPARSE_POINT, NULL);
      if (hFile == INVALID_HANDLE_VALUE) return;
      // Use GetFinalPathNameByHandleW to resolve symlinks
      wchar_t finalPath[MAX_PATH];
      GetFinalPathNameByHandleW(hFile, finalPath, MAX_PATH, VOLUME_NAME_DOS);
      CloseHandle(hFile);
      // Verify finalPath is within quarantine directory
      if (wcsncmp(finalPath, L"C:\\ProgramData\\VIPRE\\Quarantine\\", 36) != 0) {
          // Deny operation
          return;
      }
      DeleteFileW(userPath.c_str());
  }
  

The patch would involve using CreateFile with FILE_FLAG_OPEN_REPARSE_POINT to avoid following symlinks, or resolving the final path and validating it against an allowlist.

Exploitation & Lab Setup

Red Team (Attack Simulation)

Prerequisites:

• Local low-privileged access to a Windows system running VIPRE Antivirus Plus (vulnerable version).
• Ability to create symbolic links (requires SeCreateSymbolicLinkPrivilege, which is often granted to low-privileged users by default on some systems, or can be obtained via other means).

Exploitation Steps:

1. Identify the target file: Choose a file that, when deleted, will cause privilege escalation. Common targets include:
   • C:\Windows\System32\config\SAM (requires backup restore)
   • C:\Windows\System32\drivers\etc\hosts (less impactful)
   • A DLL loaded by a SYSTEM service (e.g., C:\Program Files\VIPRE\*.dll)
2. Create a symlink: Use mklink or CreateSymbolicLink API to create a link from a path that FPQuarTransfer will access to the target file.

   mklink C:\Users\Public\test_link.txt C:\Windows\System32\config\SAM
   

3. Trigger the vulnerability: The exact trigger depends on the product's behavior. It may involve:
   • Placing a file in the quarantine directory and then triggering a scan or manual quarantine action.
   • Sending a crafted IPC message to the VIPRE service.
4. Escalate privileges: After the target file is deleted, exploit the resulting system state (e.g., reboot to gain SYSTEM shell via a service failure).

Note: No public exploit code is available. This is a conceptual approach.

Blue Team (Detection & Defense)

Detection:

• Monitor for unusual symlink creation events (Event ID 4663 with access mask 0x1 (Delete) on symlink creation).
• Monitor file deletion events on critical system files (Event ID 4659, 4660).
• Use Sysmon to log process creation and file operations.

Defense:

• Apply the vendor patch when available.
• Restrict SeCreateSymbolicLinkPrivilege to administrators only.
• Enable Windows Defender Attack Surface Reduction (ASR) rules to block symlink abuse.
• Use application whitelisting to prevent unauthorized code execution.

Indicators of Compromise (IOCs)

• File System:
  • Unexpected symbolic links in user-writable directories pointing to system files.
  • Deletion of critical system files (e.g., SAM, SYSTEM, SECURITY hives).
• Process:
  • FPQuarTransfer process (likely VipreQuarantineService.exe or similar) performing file operations on user-controlled paths.
• Event Logs:
  • Windows Security Event ID 4663 (An attempt was made to access an object) with AccessMask: DELETE on a symlink.
  • Windows Security Event ID 4659 (A handle to an object was requested with intent to delete).
  • Sysmon Event ID 11 (FileCreate) for symlink creation.
  • Sysmon Event ID 23 (FileDelete) for deletion of protected files.

Detection Engineering

YARA Rule

rule CVE_2023_32179_VIPRE_LPE {
    meta:
        description = "Detects potential exploitation of CVE-2023-32179 via symlink creation or file deletion patterns"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "https://nvd.nist.gov/vuln/detail/CVE-2023-32179"
    strings:
        $s1 = "FPQuarTransfer" ascii wide nocase
        $s2 = "VipreQuarantineService" ascii wide nocase
        $s3 = "\\System32\\config\\SAM" ascii wide nocase
        $s4 = "\\System32\\config\\SYSTEM" ascii wide nocase
    condition:
        (uint16(0) == 0x5A4D or uint16(0) == 0x4D5A) and // PE file
        (1 of ($s1, $s2)) and
        (1 of ($s3, $s4))
}

Sigma Rule

title: CVE-2023-32179 - VIPRE Antivirus Plus Local Privilege Escalation via Symlink
id: 8a4b3c2d-1e5f-4a7b-9c8d-0e1f2a3b4c5d
status: experimental
description: Detects symlink creation pointing to critical system files, indicative of CVE-2023-32179 exploitation.
author: Valters IT
date: 2025-04-10
references:
    - https://nvd.nist.gov/vuln/detail/CVE-2023-32179
logsource:
    product: windows
    service: security
    category: file_event
detection:
    selection:
        EventID: 4663
        ObjectName|contains:
            - '\\System32\\config\\SAM'
            - '\\System32\\config\\SYSTEM'
            - '\\System32\\config\\SECURITY'
        AccessMask: '0x1' # DELETE
    condition: selection
falsepositives:
    - Legitimate backup or recovery operations
level: high
tags:
    - attack.privilege_escalation
    - attack.t1068

Suricata Rule

alert tcp $HOME_NET any -> $EXTERNAL_NET any (msg:"CVE-2023-32179 VIPRE LPE - Potential Symlink Abuse"; flow:to_server,established; content:"|5c 00 53 00 79 00 73 00 74 00 65 00 6d 00 33 00 32 00 5c 00 63 00 6f 00 6e 00 66 00 69 00 67 00 5c 00 53 00 41 00 4d 00|"; nocase; classtype:attempted-admin; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Apply Vendor Patch: Check VIPRE's official website or support portal for a security update. If unavailable, contact VIPRE support.
2. Restrict Symlink Creation: Use Group Policy to remove SeCreateSymbolicLinkPrivilege from non-administrator users.
3. Monitor Critical Files: Enable auditing on C:\Windows\System32\config\ and other sensitive paths.
4. Use ASR Rules: Enable "Block abuse of exploited vulnerable signed drivers" and "Block executable files from running unless they meet a prevalence, age, or trusted list criterion".

Long-Term:

• Implement least privilege principles.
• Deploy endpoint detection and response (EDR) solutions with behavioral analysis.
• Regularly review and update security policies.

Valters IT