CVE-2024-57784

Executive Summary

CVE-2024-57784 is a directory traversal vulnerability in Zenitel AlphaWeb XE v11.2.3.10, specifically within the /php/script_uploads.php component. This flaw allows an unauthenticated attacker to read arbitrary files on the server, potentially exposing sensitive configuration data, credentials, or source code. The vulnerability is publicly known with a proof-of-concept available, but no official patch has been released by Zenitel at this time. The EPSS score is 0.0%, indicating low exploitation activity in the wild, but the risk remains significant for exposed instances.

Supply Chain & Package Security

This vulnerability is not related to NPM, PyPI, Go, or Ruby packages. It is a custom PHP application vulnerability in the Zenitel AlphaWeb XE product.

CVSS Breakdown & Threat Level

While a CVSS vector is not officially assigned, based on the vulnerability characteristics, a reasonable assessment is:

• Attack Vector (AV): Network (N) – exploitable remotely.
• Attack Complexity (AC): Low (L) – no special conditions required.
• Privileges Required (PR): None (N) – no authentication needed.
• User Interaction (UI): None (N) – no user action required.
• Scope (S): Unchanged (U) – the vulnerable component is the only one affected.
• Confidentiality (C): High (H) – arbitrary file read can expose sensitive data.
• Integrity (I): None (N) – no file modification.
• Availability (A): None (N) – no denial of service.

Estimated CVSS Score: 7.5 (High)

Threat Level: High. The ease of exploitation and potential for sensitive data exposure make this a critical concern for any organization using Zenitel AlphaWeb XE.

Deep Dive & Mechanics

The vulnerability resides in the /php/script_uploads.php script. This script is likely used for file upload functionality, but it fails to properly sanitize user-supplied input in a file path parameter. An attacker can inject path traversal sequences (e.g., ../) to navigate outside the intended upload directory and read arbitrary files on the server's filesystem.

The core issue is a lack of input validation. The application likely takes a parameter (e.g., file, path, or similar) and uses it directly in a file read operation without checking for directory traversal characters. This allows an attacker to read files such as /etc/passwd, application configuration files, or other sensitive data.

Vulnerable vs. Patched Code

Vulnerable Code (Conceptual):

<?php
$file = $_GET['file'];
$content = file_get_contents('/var/www/uploads/' . $file);
echo $content;
?>

Patched Code (Conceptual):

<?php
$file = basename($_GET['file']);
$file = str_replace('../', '', $file);
$file = str_replace('..\\', '', $file);
$allowed_path = realpath('/var/www/uploads/');
$requested_path = realpath('/var/www/uploads/' . $file);
if (strpos($requested_path, $allowed_path) !== 0) {
    die('Invalid path.');
}
$content = file_get_contents($requested_path);
echo $content;
?>

The patched version uses basename() to strip directory components, removes traversal sequences, and validates that the resolved path is within the allowed directory.

Exploitation & Lab Setup

Red Team

Proof-of-Concept (PoC) Exploit:

curl "http://target.com/php/script_uploads.php?file=../../../../etc/passwd"

This command attempts to read the /etc/passwd file. The attacker can modify the path to target other files, such as:

• /etc/shadow (if permissions allow)
• /var/www/html/config.php (application configuration)
• /proc/self/environ (environment variables)

Lab Setup:

1. Deploy a vulnerable instance of Zenitel AlphaWeb XE v11.2.3.10 in a controlled environment.
2. Ensure the web server is accessible from the attacker machine.
3. Execute the curl command above to verify the vulnerability.

Blue Team

Detection & Prevention:

• Web Application Firewall (WAF): Deploy rules to block requests containing ../ or ..\\ in query parameters.
• Input Validation: Ensure the application validates and sanitizes all user-supplied file paths.
• Least Privilege: Run the web server with minimal filesystem permissions to limit the impact of a successful traversal.
• File Integrity Monitoring (FIM): Monitor for unauthorized access to sensitive files.

Indicators of Compromise (IOCs)

• Network:
  • HTTP GET requests to /php/script_uploads.php with file parameter containing ../ sequences.
  • Outbound connections from the server to unknown IPs (if data exfiltration occurs).
• File System:
  • Unexpected access to /etc/passwd, /etc/shadow, or application configuration files.
  • Log entries showing file read operations outside the web root.
• Logs:
  • Web server access logs showing requests with path traversal patterns.
  • Application error logs indicating failed file read attempts.

Detection Engineering

YARA Rule

rule CVE_2024_57784_Directory_Traversal {
    meta:
        description = "Detects directory traversal attempts targeting Zenitel AlphaWeb XE script_uploads.php"
        author = "Valters IT"
        date = "2024-01-01"
        reference = "CVE-2024-57784"
    strings:
        $traversal = /\.\.\// nocase
        $script = "/php/script_uploads.php" nocase
    condition:
        $script and #traversal > 0
}

Sigma Rule

title: CVE-2024-57784 Directory Traversal Attempt
id: 12345678-1234-1234-1234-123456789012
status: experimental
description: Detects directory traversal attempts against Zenitel AlphaWeb XE
author: Valters IT
date: 2024/01/01
logsource:
    category: webserver
    product: apache
detection:
    selection:
        cs-uri-query|contains: 
            - '/php/script_uploads.php'
        cs-uri-query|contains|all:
            - 'file='
            - '../'
    condition: selection
falsepositives:
    - Legitimate use of '..' in file names (rare)
level: high

Suricata Rule

alert http any any -> any any (msg:"CVE-2024-57784 Directory Traversal Attempt"; flow:to_server,established; content:"/php/script_uploads.php"; http_uri; content:"file="; http_uri; content:"../"; http_uri; classtype:attempted-recon; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Isolate: If possible, isolate the affected system from the network until a patch is applied.
2. WAF Rules: Implement virtual patching via a WAF to block directory traversal patterns.
3. Input Validation: Manually patch the application code to sanitize file paths (see patched code example).

Long-Term Fix:

• Apply the official patch from Zenitel once released.
• Conduct a security audit of the entire application for similar vulnerabilities.
• Implement a secure coding standard that includes input validation and path sanitization.

Workarounds:

• Disable the /php/script_uploads.php endpoint if not required.
• Restrict access to the endpoint via IP whitelisting or authentication.

Valters IT