CVE-2021-31671
📋 TL;DR
CVE-2021-31671 is an information disclosure vulnerability in pgsync that can expose sensitive database connection parameters. When using --schema-first or --schema-only options, SSL/TLS connection parameters may be lost, potentially transmitting data unencrypted. This affects all users of pgsync versions before 0.6.7 who sync PostgreSQL databases with sensitive data.
💻 Affected Systems
- pgsync
📦 What is this software?
Pgsync by Pgsync Project
⚠️ Risk & Real-World Impact
Worst Case
Database credentials and sensitive data transmitted in cleartext over network, leading to full database compromise and data breach.
Likely Case
Database synchronization occurs without SSL/TLS encryption, exposing data to network sniffing and man-in-the-middle attacks.
If Mitigated
If network segmentation and encryption are properly implemented, risk is limited to potential credential exposure.
🎯 Exploit Status
Exploitation requires network access to intercept traffic between pgsync and PostgreSQL database. No authentication bypass needed as it's a configuration mishandling issue.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 0.6.7 and later
Vendor Advisory: https://github.com/ankane/pgsync/issues/121
Restart Required: No
Instructions:
1. Update pgsync to version 0.6.7 or later using 'gem update pgsync'. 2. Verify the update with 'pgsync --version'. 3. Test synchronization with --schema-first or --schema-only options to ensure SSL/TLS is maintained.
🔧 Temporary Workarounds
Avoid vulnerable options
allDo not use --schema-first or --schema-only options until patched
# Use standard sync without vulnerable options
pgsync --from production --to staging
Force SSL in PostgreSQL connection
linuxConfigure PostgreSQL to require SSL connections regardless of client settings
# In postgresql.conf:
ssl = on
ssl_cert_file = 'server.crt'
ssl_key_file = 'server.key'
# In pg_hba.conf:
hostssl all all 0.0.0.0/0 md5
🧯 If You Can't Patch
- Use VPN or encrypted tunnel for all database synchronization traffic
- Implement network segmentation and monitor for unencrypted database traffic
🔍 How to Verify
Check if Vulnerable:
Run 'pgsync --version' and check if version is below 0.6.7. Also check if you use --schema-first or --schema-only options in your sync commands.Check Version:
pgsync --versionVerify Fix Applied:
After updating, run 'pgsync --version' to confirm version 0.6.7+. Test a sync with --schema-first option while monitoring network traffic to ensure SSL/TLS is used.📡 Detection & Monitoring
Log Indicators:
- Database connection attempts without SSL/TLS
- pgsync errors related to SSL configuration
- Unencrypted PostgreSQL protocol traffic in logs
Network Indicators:
- PostgreSQL traffic on port 5432 without TLS encryption
- Cleartext database credentials in network captures
SIEM Query:
source="pgsync" AND ("--schema-first" OR "--schema-only") AND version<"0.6.7"