CVE-2020-5024
📋 TL;DR
This vulnerability allows an unauthenticated attacker to cause a denial of service by triggering a hang during SSL handshake responses in IBM DB2. Affected systems include IBM DB2 for Linux, UNIX and Windows (including DB2 Connect Server) versions 9.7 through 11.5.
💻 Affected Systems
- IBM DB2 for Linux, UNIX and Windows
- IBM DB2 Connect Server
📦 What is this software?
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Db2 by Ibm
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Db2 by Ibm
Db2 by Ibm
Db2 by Ibm
Db2 by Ibm
Db2 by Ibm
Db2 by Ibm
Db2 by Ibm
Db2 by Ibm
Db2 by Ibm
Db2 by Ibm
Db2 by Ibm
Db2 by Ibm
Db2 by Ibm
Db2 by Ibm
Db2 by Ibm
Db2 by Ibm
Db2 by Ibm
Db2 by Ibm
Db2 by Ibm
Db2 by Ibm
Db2 by Ibm
⚠️ Risk & Real-World Impact
Worst Case
Complete service outage of DB2 database instances, disrupting all database operations and dependent applications.
Likely Case
Intermittent service disruptions affecting database availability and performance.
If Mitigated
Minimal impact with proper network segmentation and SSL/TLS configuration controls.
🎯 Exploit Status
The vulnerability requires network access to the DB2 SSL port but no authentication.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Apply fixes as specified in IBM advisory APARs
Vendor Advisory: https://www.ibm.com/support/pages/node/6427861
Restart Required: Yes
Instructions:
1. Review IBM advisory for specific APAR fixes for your version. 2. Apply the appropriate fix pack or interim fix. 3. Restart DB2 services to apply changes.
🔧 Temporary Workarounds
Disable SSL/TLS
allTemporarily disable SSL/TLS connections if not required, though this reduces security.
Modify DB2 configuration to use non-SSL ports only
Network Access Control
allRestrict network access to DB2 SSL ports using firewall rules.
iptables -A INPUT -p tcp --dport <db2_ssl_port> -j DROP (Linux)
netsh advfirewall firewall add rule name="Block DB2 SSL" dir=in action=block protocol=TCP localport=<db2_ssl_port> (Windows)
🧯 If You Can't Patch
- Implement strict network segmentation to isolate DB2 instances from untrusted networks
- Deploy intrusion detection/prevention systems to monitor for SSL handshake anomalies
🔍 How to Verify
Check if Vulnerable:
Check DB2 version and compare against affected versions list. Verify SSL/TLS is enabled.Check Version:
db2level (Linux/UNIX) or check DB2 installation details (Windows)Verify Fix Applied:
Verify applied fix pack version matches IBM's remediation guidance and test SSL connections.📡 Detection & Monitoring
Log Indicators:
- Multiple SSL handshake failures
- DB2 process hangs or abnormal termination
- Increased connection timeouts
Network Indicators:
- Abnormal SSL/TLS traffic patterns to DB2 ports
- Repeated connection attempts to DB2 SSL ports
SIEM Query:
source="db2" AND (event="SSL handshake failure" OR event="connection timeout")🔗 References
- https://exchange.xforce.ibmcloud.com/vulnerabilities/193660
- https://security.netapp.com/advisory/ntap-20210409-0003/
- https://www.ibm.com/support/pages/node/6427861
- https://exchange.xforce.ibmcloud.com/vulnerabilities/193660
- https://security.netapp.com/advisory/ntap-20210409-0003/
- https://www.ibm.com/support/pages/node/6427861
