CVE-2020-23877
📋 TL;DR
CVE-2020-23877 is a critical stack buffer overflow vulnerability in pdf2xml v2.0's getObjectStream component that allows remote attackers to execute arbitrary code or cause denial of service. This affects systems running pdf2xml v2.0 for PDF to XML conversion. Attackers can exploit this by providing a malicious PDF file to the vulnerable software.
💻 Affected Systems
- pdf2xml
📦 What is this software?
Pdf2xml by Science Miner
⚠️ Risk & Real-World Impact
Worst Case
Remote code execution with full system compromise, allowing attackers to install malware, steal data, or pivot to other systems.
Likely Case
Denial of service through application crashes, with potential for remote code execution in targeted attacks.
If Mitigated
Limited impact through proper input validation and memory protections, potentially reduced to denial of service only.
🎯 Exploit Status
Proof of concept code is publicly available, making exploitation straightforward for attackers with basic skills.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Not available
Vendor Advisory: https://github.com/kermitt2/pdf2xml/issues/15
Restart Required: No
Instructions:
No official patch exists. Consider migrating to alternative PDF parsing libraries or implementing the workarounds below.
🔧 Temporary Workarounds
Input Validation and Sanitization
allImplement strict input validation for PDF files before processing with pdf2xml
# Implement custom validation script to check PDF structure before processing
# Example: Use pdfid.py or similar tools to analyze PDF before passing to pdf2xml
Memory Protection Controls
linuxEnable stack protection and address space layout randomization (ASLR)
# Linux: sysctl -w kernel.randomize_va_space=2
# Compile with: -fstack-protector-all -D_FORTIFY_SOURCE=2
🧯 If You Can't Patch
- Isolate pdf2xml systems in network segments with strict egress filtering
- Implement application allowlisting to prevent unauthorized execution of pdf2xml
🔍 How to Verify
Check if Vulnerable:
Check if pdf2xml version 2.0 is installed: 'pdf2xml --version' or check package managerCheck Version:
pdf2xml --version 2>&1 | grep -i versionVerify Fix Applied:
Verify pdf2xml is no longer in use or has been replaced with alternative software📡 Detection & Monitoring
Log Indicators:
- Multiple pdf2xml process crashes
- Large or malformed PDF file processing attempts
- Unusual memory allocation patterns in system logs
Network Indicators:
- Unexpected network connections from pdf2xml processes
- PDF file uploads to systems running pdf2xml
SIEM Query:
process_name="pdf2xml" AND (event_type="crash" OR memory_usage>threshold)