CVE-2020-5426
📋 TL;DR
CVE-2020-5426 allows attackers to intercept UAA client tokens transmitted in plaintext over non-TLS connections, potentially granting admin-level access to the cloud controller. This affects Scheduler for TAS (Tanzu Application Service) deployments with vulnerable configurations. Organizations using affected versions without proper TLS enforcement are at risk.
💻 Affected Systems
- Scheduler for TAS (Tanzu Application Service)
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Full compromise of cloud controller with admin privileges, allowing complete control over application deployments, services, and infrastructure.
Likely Case
Unauthorized access to sensitive cloud controller functions, potentially leading to data exposure, application disruption, or privilege escalation.
If Mitigated
Limited impact with proper network segmentation and TLS enforcement, though risk remains if MySQL cache is compromised.
🎯 Exploit Status
Requires network access to intercept plaintext traffic and knowledge of the system architecture.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 1.4.0
Vendor Advisory: https://tanzu.vmware.com/security/cve-2020-5426
Restart Required: Yes
Instructions:
1. Upgrade Scheduler for TAS to version 1.4.0 or later. 2. Ensure MySQL server is configured to use TLS for connections. 3. Restart affected services.
🔧 Temporary Workarounds
Enforce TLS for all connections
allConfigure Scheduler and MySQL to require TLS encryption for all network traffic
Configure TLS in Scheduler properties: scheduler.tls.enabled=true
Configure MySQL to require SSL: require_secure_transport=ON
Network segmentation
allIsolate Scheduler and MySQL components in a protected network segment
🧯 If You Can't Patch
- Enforce TLS encryption on all network connections between Scheduler and MySQL components
- Implement network monitoring and intrusion detection for plaintext token transmission attempts
🔍 How to Verify
Check if Vulnerable:
Check Scheduler version: if <1.4.0 and MySQL connections are not using TLS, system is vulnerableCheck Version:
Check Scheduler deployment manifest or BOSH deployment for version informationVerify Fix Applied:
Verify Scheduler version is 1.4.0+ and confirm TLS is enforced for all MySQL connections📡 Detection & Monitoring
Log Indicators:
- Plaintext authentication attempts
- Unexpected admin-level access patterns
- MySQL connection attempts without TLS
Network Indicators:
- Plaintext traffic on ports used by Scheduler/MySQL
- Suspicious token interception patterns
SIEM Query:
Search for 'plaintext' OR 'non-TLS' in Scheduler logs combined with authentication events