CVE-2021-27632
📋 TL;DR
CVE-2021-27632 is a denial-of-service vulnerability in SAP NetWeaver ABAP Server and ABAP Platform's Enqueue Server. An unauthenticated attacker can send a specially crafted network packet to trigger an internal error, causing the system to crash and become unavailable. This affects organizations running vulnerable SAP NetWeaver versions.
💻 Affected Systems
- SAP NetWeaver ABAP Server
- SAP NetWeaver ABAP Platform
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Complete system unavailability affecting business operations, requiring system restart and potentially causing data loss or service disruption.
Likely Case
Service disruption and downtime requiring manual intervention to restart affected SAP systems.
If Mitigated
No impact if patched or network controls prevent access to vulnerable services.
🎯 Exploit Status
The vulnerability requires sending a specially crafted packet to the Enqueue Server port (typically 3200-3299). No authentication or special knowledge needed.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Apply SAP Security Note 3020104
Vendor Advisory: https://launchpad.support.sap.com/#/notes/3020104
Restart Required: Yes
Instructions:
1. Download SAP Note 3020104 from SAP Support Portal. 2. Apply the kernel patch according to SAP standard procedures. 3. Restart the affected SAP systems. 4. Verify the patch is applied correctly.
🔧 Temporary Workarounds
Network Segmentation
linuxRestrict network access to Enqueue Server ports (typically 3200-3299) to only trusted systems.
firewall-cmd --permanent --add-rich-rule='rule family="ipv4" source address="TRUSTED_IP_RANGE" port protocol="tcp" port="3200-3299" accept'
firewall-cmd --reload
Windows Firewall Rule
windowsBlock external access to Enqueue Server ports on Windows systems.
New-NetFirewallRule -DisplayName "Block SAP Enqueue Ports" -Direction Inbound -LocalPort 3200-3299 -Protocol TCP -Action Block
🧯 If You Can't Patch
- Implement strict network controls to limit access to Enqueue Server ports (3200-3299) to only necessary systems.
- Monitor for unusual traffic patterns or connection attempts to Enqueue Server ports and implement rate limiting if possible.
🔍 How to Verify
Check if Vulnerable:
Check SAP kernel version using SAP transaction SM51 or OS command 'disp+work' and compare against affected versions listed in SAP Note 3020104.Check Version:
On SAP server: disp+work -version or check in SAP GUI: System -> StatusVerify Fix Applied:
Verify SAP Note 3020104 is applied using SAP transaction SNOTE or check kernel patch level in SM51.📡 Detection & Monitoring
Log Indicators:
- System crash logs in SAP work directory
- Abnormal termination of enqueue server process
- Dev_w* trace files showing access violations
Network Indicators:
- Unusual traffic to Enqueue Server ports (3200-3299)
- Multiple connection attempts from single sources
SIEM Query:
source="sap_logs" AND ("enqueue server crash" OR "access violation" OR "kernel panic") OR dest_port IN (3200, 3201, 3202, ..., 3299) AND protocol="tcp" AND NOT src_ip IN (trusted_ip_list)