CVE-2021-38599
📋 TL;DR
WAL-G backup tool versions before 1.1 silently ignore encryption keys when using official binary releases, uploading backups in cleartext instead of encrypting them. This affects users who rely on WAL-G for database backups and expect encryption to protect sensitive data. The vulnerability violates the Principle of Least Surprise as users assume encryption is active when configured.
💻 Affected Systems
- WAL-G
📦 What is this software?
Wal G by Wal G Project
⚠️ Risk & Real-World Impact
Worst Case
Sensitive database backups containing PII, financial data, or credentials are uploaded to cloud storage in cleartext, potentially exposing them to unauthorized access or data breaches.
Likely Case
Backups intended to be encrypted are stored unencrypted, creating data exposure risks if storage systems are compromised or accessed by unauthorized parties.
If Mitigated
If proper access controls exist on backup storage and monitoring detects cleartext uploads, impact is limited to potential data exposure rather than direct exploitation.
🎯 Exploit Status
No active exploitation required - vulnerability causes automatic cleartext uploads when encryption is configured but using vulnerable binaries. Attackers would need access to backup storage to benefit.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 1.1 and later
Vendor Advisory: https://github.com/wal-g/wal-g/commit/cadf598e1c2a345915a21a44518c5a4d5401e2e3
Restart Required: No
Instructions:
1. Upgrade WAL-G to version 1.1 or later. 2. Replace existing binary with patched version. 3. Verify encryption is working by testing backup creation and checking encrypted output.
🔧 Temporary Workarounds
Build with libsodium
allCompile WAL-G from source with libsodium support instead of using official binaries
go build -tags libsodium -o wal-g main/pg/main.go
Use external encryption
linuxEncrypt backups before WAL-G upload using external tools like gpg or openssl
tar czf - /data | gpg --encrypt --recipient backup@example.com | wal-g backup-push /dev/stdin
🧯 If You Can't Patch
- Audit all existing backups in storage to identify any cleartext data and secure/delete them
- Implement strict access controls on backup storage systems and enable logging/monitoring for unauthorized access attempts
🔍 How to Verify
Check if Vulnerable:
Check WAL-G version with 'wal-g --version'. If version is below 1.1 and using official binary, system is vulnerable when encryption is configured.Check Version:
wal-g --versionVerify Fix Applied:
Create test backup with encryption configured, then attempt to restore without decryption key. If restoration fails, encryption is working.📡 Detection & Monitoring
Log Indicators:
- Backup operations completing without encryption-related log entries
- Unexpectedly fast backup completion times (encryption adds overhead)
Network Indicators:
- Backup uploads to cloud storage without encrypted traffic patterns
- Cleartext database content in network captures
SIEM Query:
source="wal-g" AND (NOT "encrypt" OR NOT "libsodium") AND action="backup-push"