CVE-2020-4759
📋 TL;DR
CVE-2020-4759 is a CSV injection vulnerability in IBM FileNet Content Manager that allows remote attackers to execute arbitrary commands on affected systems. The vulnerability exists due to improper validation of CSV file contents, enabling command injection. This affects IBM FileNet Content Manager versions 5.5.4 and 5.5.5.
💻 Affected Systems
- IBM FileNet Content Manager
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Remote unauthenticated attacker gains full system control, executes arbitrary commands with system privileges, leading to complete compromise of the FileNet server and potentially lateral movement within the network.
Likely Case
Authenticated attacker with file upload privileges executes commands with application service account permissions, potentially accessing sensitive content, modifying configurations, or establishing persistence.
If Mitigated
With proper input validation and file upload restrictions, exploitation would be prevented or limited to the application's security context.
🎯 Exploit Status
Exploitation requires file upload capability, typically through authenticated interfaces. The vulnerability is in CSV parsing logic.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Apply APAR IJ28338 or upgrade to version 5.5.6
Vendor Advisory: https://www.ibm.com/support/pages/node/6336917
Restart Required: Yes
Instructions:
1. Download APAR IJ28338 from IBM Fix Central. 2. Apply the fix according to IBM documentation. 3. Restart the FileNet Content Manager services. 4. Verify the fix by testing CSV file upload functionality.
🔧 Temporary Workarounds
Restrict CSV file uploads
allImplement strict file upload controls to block or sanitize CSV files before processing
Implement input validation
allAdd server-side validation to sanitize CSV content and remove potentially malicious formulas/commands
🧯 If You Can't Patch
- Implement strict access controls to limit who can upload files to the FileNet system
- Deploy network segmentation to isolate FileNet servers from critical systems
🔍 How to Verify
Check if Vulnerable:
Check if running IBM FileNet Content Manager version 5.5.4 or 5.5.5 without APAR IJ28338 appliedCheck Version:
Check FileNet installation directory or administrative console for version informationVerify Fix Applied:
Verify APAR IJ28338 is installed or version is 5.5.6 or higher, then test CSV upload functionality with malicious content📡 Detection & Monitoring
Log Indicators:
- Unusual CSV file uploads
- Unexpected command execution in application logs
- File upload errors containing formula syntax
Network Indicators:
- Unusual outbound connections from FileNet servers
- Suspicious file upload patterns to FileNet endpoints
SIEM Query:
source="filenet" AND (event="file_upload" AND file_extension="csv") OR (event="command_execution" AND process="cmd.exe" OR process="powershell.exe")