CVE-2021-45456
📋 TL;DR
Apache Kylin 4.0.0 contains a command injection vulnerability in DiagnosisService where improper validation of project names allows attackers to execute arbitrary shell commands. This vulnerability affects all Apache Kylin 4.0.0 installations and can lead to complete system compromise.
💻 Affected Systems
- Apache Kylin
📦 What is this software?
Kylin by Apache
Kylin by Apache
Kylin by Apache
⚠️ Risk & Real-World Impact
Worst Case
Full remote code execution with root/system privileges, allowing complete takeover of the server, data exfiltration, and lateral movement within the network.
Likely Case
Remote code execution with the privileges of the Kylin service account, enabling data theft, service disruption, and installation of backdoors.
If Mitigated
Limited impact if proper network segmentation, least privilege service accounts, and input validation are implemented.
🎯 Exploit Status
The vulnerability is well-documented with public proof-of-concept available, making exploitation straightforward for attackers.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Apache Kylin 4.0.1 or later
Vendor Advisory: https://lists.apache.org/thread/70fkf9w1swt2cqdcz13rwfjvblw1fcpf
Restart Required: Yes
Instructions:
1. Backup your Kylin configuration and data. 2. Stop the Kylin service. 3. Upgrade to Apache Kylin 4.0.1 or later. 4. Restart the Kylin service. 5. Verify the fix by testing project name validation.
🔧 Temporary Workarounds
Network Isolation
linuxRestrict network access to Kylin instances to only trusted IP addresses
iptables -A INPUT -p tcp --dport 7070 -s trusted_ip -j ACCEPT
iptables -A INPUT -p tcp --dport 7070 -j DROP
Service Account Restriction
linuxRun Kylin with a non-privileged service account with minimal permissions
useradd -r -s /bin/false kylin_user
chown -R kylin_user:kylin_user /opt/kylin
🧯 If You Can't Patch
- Implement strict network segmentation and firewall rules to limit access to Kylin instances
- Deploy web application firewall (WAF) rules to block command injection patterns in project names
🔍 How to Verify
Check if Vulnerable:
Check if running Apache Kylin version 4.0.0 by examining version files or service outputCheck Version:
cat /opt/kylin/version.txt 2>/dev/null || grep -i version /opt/kylin/logs/*.logVerify Fix Applied:
Verify installation of Apache Kylin 4.0.1 or later and test that project names with shell metacharacters are properly rejected📡 Detection & Monitoring
Log Indicators:
- Unusual shell commands in Kylin logs
- Project names containing shell metacharacters like ;, |, &, $
- Failed authentication attempts followed by successful command execution
Network Indicators:
- Unusual outbound connections from Kylin server
- Traffic to unexpected ports from Kylin service
SIEM Query:
source="kylin.logs" AND ("DiagnosisService" OR "project.*[;&|$]")