CVE-2023-32177

Executive Summary

CVE-2023-32177 is a high-severity (CVSS 7.8) local privilege escalation vulnerability in VIPRE Antivirus Plus. The flaw resides in the DeleteHistoryFile method, which fails to properly validate user-supplied paths before performing file operations. This allows an attacker with low-privileged code execution on the target system to delete arbitrary files or write to arbitrary locations, ultimately achieving code execution in the context of SYSTEM. The vulnerability was reported via ZDI (ZDI-CAN-19395) and currently has no official patch or public exploit code. The EPSS score is 0.0%, indicating low exploitation activity in the wild, but the risk remains significant for enterprise environments using VIPRE Antivirus Plus.

Supply Chain & Package Security

This vulnerability is not related to open-source package ecosystems (NPM, PyPI, Go, Ruby). It affects a proprietary Windows antivirus product. No supply chain implications are identified.

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: 7.8 (High)
• Attack Vector: Local (AV:L) – requires local access to the system.
• Attack Complexity: Low (AC:L) – no special conditions needed.
• Privileges Required: Low (PR:L) – attacker needs initial low-privileged code execution.
• User Interaction: None (UI:N) – no user action required.
• Scope: Unchanged (S:U) – vulnerability does not cross trust boundaries.
• Confidentiality Impact: High (C:H) – potential to read sensitive system files.
• Integrity Impact: High (I:H) – arbitrary file deletion/write.
• Availability Impact: High (A:H) – could delete critical system files causing denial of service.

Threat Level: High. While no public exploit exists, the vulnerability is trivial to exploit once low-privileged access is obtained. It can be chained with other initial access vectors (e.g., phishing, drive-by download) to achieve full system compromise.

Deep Dive & Mechanics

The vulnerability is a classic directory traversal (path traversal) in the DeleteHistoryFile method of VIPRE Antivirus Plus. The method is likely exposed via a local inter-process communication (IPC) mechanism (e.g., named pipe, COM interface, or Windows service) that runs with SYSTEM privileges.

Root Cause: The method accepts a user-supplied path string but does not validate or sanitize it for directory traversal sequences (e.g., ..\). When a low-privileged process calls this method, it can specify a path like ..\..\Windows\System32\config\SAM to delete or overwrite sensitive system files.

Attack Flow:

1. Attacker gains low-privileged code execution on the target (e.g., via malicious macro, browser exploit, or social engineering).
2. Attacker identifies the IPC endpoint for VIPRE’s DeleteHistoryFile method (likely a named pipe or RPC interface).
3. Attacker crafts a request with a path traversal payload, e.g., ..\..\Windows\System32\drivers\etc\hosts.
4. The VIPRE service, running as SYSTEM, executes the file operation on the attacker-controlled path.
5. Attacker can delete critical files (e.g., security software binaries) or write malicious files (e.g., a DLL in a startup folder) to escalate privileges.

Why It Works: The VIPRE service runs with high integrity (SYSTEM), so any file operation it performs inherits those privileges. The lack of path validation allows the attacker to escape the intended sandboxed directory.

Vulnerable vs. Patched Code

Since no official patch is available, the vulnerable code pattern is described hypothetically based on the CVE description.

Vulnerable Code (C#/C++ pseudocode):

public void DeleteHistoryFile(string relativePath)
{
    string basePath = @"C:\ProgramData\VIPRE\History\";
    string fullPath = Path.Combine(basePath, relativePath);
    // No validation of relativePath for ".." sequences
    File.Delete(fullPath);
}

Patched Code (Expected):

public void DeleteHistoryFile(string relativePath)
{
    string basePath = @"C:\ProgramData\VIPRE\History\";
    string fullPath = Path.GetFullPath(Path.Combine(basePath, relativePath));
    // Validate that the resolved path is still within the base directory
    if (!fullPath.StartsWith(basePath, StringComparison.OrdinalIgnoreCase))
    {
        throw new UnauthorizedAccessException("Invalid path.");
    }
    File.Delete(fullPath);
}

Key Differences:

• The patched version uses Path.GetFullPath to resolve any .. sequences.
• It then checks that the resolved path starts with the intended base directory.
• This prevents directory traversal attacks.

Exploitation & Lab Setup

Red Team (Exploitation)

Prerequisites:

• Low-privileged shell on a Windows system with VIPRE Antivirus Plus installed.
• Knowledge of the IPC endpoint (e.g., named pipe \\.\pipe\VIPRE_HistoryService).

Exploit Steps:

1. Enumerate the IPC endpoint using tools like pipelist or PowerShell:

   Get-ChildItem \\.\pipe\ | Where-Object {$_.Name -like "*VIPRE*"}
   

2. Connect to the named pipe and send a crafted request:

   using System.IO.Pipes;
   using System.Text;
   
   NamedPipeClientStream pipeClient = new NamedPipeClientStream(".", "VIPRE_HistoryService");
   pipeClient.Connect();
   StreamWriter sw = new StreamWriter(pipeClient);
   // Path traversal payload to delete a critical file
   sw.WriteLine("DeleteHistoryFile:..\\..\\Windows\\System32\\drivers\\etc\\hosts");
   sw.Flush();
   pipeClient.Close();
   

3. Verify privilege escalation by attempting to write a malicious DLL to a startup folder:

   sw.WriteLine("DeleteHistoryFile:..\\..\\Users\\Public\\Startup\\malicious.dll");
   

4. After the file is placed, the next user login will execute the DLL with SYSTEM privileges.

Note: No public exploit code exists. The above is a conceptual example.

Blue Team (Detection & Response)

Detection Steps:

1. Monitor for unusual named pipe connections to VIPRE services from non-VIPRE processes.
2. Look for file operations on paths outside C:\ProgramData\VIPRE\History\ performed by the VIPRE service process.
3. Alert on any DeleteHistoryFile calls with path traversal patterns (..\).

Hunting Query (Sysmon Event ID 11 - FileCreate):

<QueryList>
  <Query Id="0" Path="Microsoft-Windows-Sysmon/Operational">
    <Select Path="Microsoft-Windows-Sysmon/Operational">
      *[System[(EventID=11)]]
      and
      *[EventData[Data[@Name='Image'] and (contains(.,'VIPRE') or contains(.,'Vipre'))]]
      and
      *[EventData[Data[@Name='TargetFilename'] and (contains(.,'..\') or contains(.,'..\\'))]]
    </Select>
  </Query>
</QueryList>

Indicators of Compromise (IOCs)

Behavioral IOCs:

• Unusual file deletions in C:\Windows\System32\drivers\etc\ or C:\Windows\System32\config\ by VIPRE processes.
• Creation of files in startup folders (C:\Users\*\AppData\Roaming\Microsoft\Windows\Start Menu\Programs\Startup\) by VIPRE processes.

Detection Engineering

YARA Rule

rule CVE_2023_32177_VIPRE_DirectoryTraversal {
    meta:
        description = "Detects attempts to exploit CVE-2023-32177 directory traversal in VIPRE Antivirus Plus"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "https://nvd.nist.gov/vuln/detail/CVE-2023-32177"
        severity = "high"
    strings:
        $s1 = "DeleteHistoryFile" ascii wide nocase
        $s2 = "..\\" ascii wide
        $s3 = "..\\..\\" ascii wide
    condition:
        all of ($s1, $s2) or all of ($s1, $s3)
}

Sigma Rule

title: CVE-2023-32177 VIPRE Antivirus Plus Directory Traversal
id: 8a9b3c4d-5e6f-7a8b-9c0d-1e2f3a4b5c6d
status: experimental
description: Detects file operations by VIPRE service with path traversal patterns
author: Valters IT
date: 2025-04-10
references:
    - https://nvd.nist.gov/vuln/detail/CVE-2023-32177
logsource:
    product: windows
    service: sysmon
    definition: 'Requires Sysmon EventID 11 (FileCreate) or EventID 23 (FileDelete)'
detection:
    selection:
        EventID:
            - 11
            - 23
        Image|contains: 'VIPRE'
        TargetFilename|contains: '..\\'
    condition: selection
falsepositives:
    - Legitimate VIPRE operations within its own directory (unlikely to contain '..\\')
level: high

Suricata Rule

alert ip any any -> any any (msg:"CVE-2023-32177 VIPRE Directory Traversal Attempt"; content:"DeleteHistoryFile"; nocase; content:"..\\"; distance:0; within:100; classtype:attempted-admin; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Isolate affected systems: If VIPRE Antivirus Plus is in use, consider removing or disabling the product until a patch is available.
2. Restrict low-privileged access: Implement least privilege principles to limit the ability of attackers to gain initial code execution.
3. Monitor IPC endpoints: Use Windows Defender Firewall or AppLocker to block unauthorized access to VIPRE named pipes.

Long-Term Fix:

• Vendor patch: Await an official update from VIPRE that implements proper path validation (as described in the patched code section).
• Workaround: If patching is not possible, consider replacing VIPRE Antivirus Plus with an alternative security solution.

Compensating Controls:

• Enable Windows Defender Attack Surface Reduction (ASR) rules to block process creation from untrusted sources.
• Use Sysmon to monitor for the IOCs listed above.
• Implement application whitelisting to prevent unauthorized executables.

Valters IT