CVE-2021-21446
📋 TL;DR
CVE-2021-21446 is a denial-of-service vulnerability in SAP NetWeaver AS ABAP that allows unauthenticated attackers to crash or flood the service, preventing legitimate users from accessing it. This affects SAP NetWeaver AS ABAP versions 740 through 755. Organizations running these versions without patches are vulnerable to service disruption.
💻 Affected Systems
- SAP NetWeaver Application Server ABAP
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Complete service outage of SAP NetWeaver AS ABAP, disrupting critical business operations dependent on SAP applications.
Likely Case
Service degradation or temporary unavailability affecting user productivity and business processes.
If Mitigated
Minimal impact with proper network segmentation and patching, though some resource consumption may still occur.
🎯 Exploit Status
The vulnerability description indicates unauthenticated exploitation is possible, suggesting relatively simple attack vectors.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Apply SAP Security Note 3000306
Vendor Advisory: https://launchpad.support.sap.com/#/notes/3000306
Restart Required: Yes
Instructions:
1. Download SAP Note 3000306 from SAP Support Portal. 2. Apply the note using SAP Note Assistant or manual implementation. 3. Restart the affected SAP NetWeaver AS ABAP instances. 4. Verify the patch is applied correctly.
🔧 Temporary Workarounds
Network Access Control
allRestrict network access to SAP NetWeaver AS ABAP services to trusted IP addresses only.
Use firewall rules to limit access to SAP ports (e.g., 3200, 3300, 3600) to authorized networks
Load Balancer Rate Limiting
allImplement rate limiting on network devices or load balancers to prevent flooding attacks.
Configure rate limiting rules on your network infrastructure for SAP service ports
🧯 If You Can't Patch
- Implement strict network segmentation to isolate SAP systems from untrusted networks
- Deploy intrusion prevention systems (IPS) with DoS protection capabilities in front of SAP services
🔍 How to Verify
Check if Vulnerable:
Check SAP system version via transaction SM51 or SM50 and compare against affected versions list.Check Version:
In SAP GUI, execute transaction SM51 or run 'disp+work' command at OS level.Verify Fix Applied:
Verify SAP Note 3000306 is applied using transaction SNOTE or by checking system patch status.📡 Detection & Monitoring
Log Indicators:
- Unusual connection patterns to SAP services
- Service restart events in system logs
- High resource consumption alerts
Network Indicators:
- Abnormal traffic spikes to SAP ports
- Connection attempts from unexpected sources
SIEM Query:
source="sap_logs" AND (event_type="service_restart" OR connection_count > threshold)