CVE-2021-27607
📋 TL;DR
CVE-2021-27607 is a denial-of-service vulnerability in SAP NetWeaver ABAP Server and ABAP Platform that allows unauthenticated attackers to crash the system by sending specially crafted network packets. The vulnerability affects multiple kernel versions and renders systems unavailable without allowing data access or modification. Organizations running affected SAP NetWeaver versions are at risk.
💻 Affected Systems
- SAP NetWeaver ABAP Server
- SAP NetWeaver ABAP Platform
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Complete system unavailability causing business disruption, requiring system restart and potential data loss from interrupted transactions.
Likely Case
Service disruption affecting SAP applications and business processes until system restart.
If Mitigated
Minimal impact if systems are patched, network-restricted, or behind proper security controls.
🎯 Exploit Status
The vulnerability requires sending specially crafted packets but doesn't require authentication or specific system knowledge, making exploitation relatively straightforward.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Apply SAP Security Note 3021197
Vendor Advisory: https://launchpad.support.sap.com/#/notes/3021197
Restart Required: Yes
Instructions:
1. Download SAP Note 3021197 from SAP Support Portal. 2. Apply the kernel patch according to SAP's instructions. 3. Restart affected SAP systems. 4. Verify patch application using transaction SM51.
🔧 Temporary Workarounds
Network Segmentation
linuxRestrict network access to SAP Dispatcher ports (typically 3200-3299) to trusted sources only.
firewall-cmd --permanent --add-rich-rule='rule family="ipv4" source address="TRUSTED_NETWORK" port protocol="tcp" port="3200-3299" accept'
firewall-cmd --reload
Windows Firewall Rule
windowsCreate Windows firewall rules to restrict access to SAP Dispatcher ports.
New-NetFirewallRule -DisplayName "SAP Dispatcher Restrict" -Direction Inbound -LocalPort 3200-3299 -Protocol TCP -Action Allow -RemoteAddress TRUSTED_IP_RANGE
🧯 If You Can't Patch
- Implement strict network access controls to limit connections to SAP Dispatcher ports from trusted sources only.
- Deploy intrusion prevention systems (IPS) or web application firewalls (WAF) configured to detect and block exploitation attempts.
🔍 How to Verify
Check if Vulnerable:
Check kernel version using transaction SM51 or command 'disp+work -version'. Compare against affected versions listed in SAP Note 3021197.Check Version:
disp+work -version (on OS level) or check in SAP transaction SM51Verify Fix Applied:
Verify SAP Note 3021197 is applied using transaction SNOTE or by checking kernel patch level in SM51.📡 Detection & Monitoring
Log Indicators:
- Dispatcher crash logs in dev_disp
- System termination messages in SAP system logs
- Abnormal termination of disp+work processes
Network Indicators:
- Unusual traffic patterns to SAP Dispatcher ports (3200-3299)
- Multiple connection attempts from single sources
SIEM Query:
source="sap_logs" AND ("dispatcher crash" OR "disp+work terminated" OR "internal error ThSncIn")