CVE-2022-27615
📋 TL;DR
This path traversal vulnerability in Synology DNS Server allows authenticated remote attackers to delete arbitrary files on the system. It affects Synology DNS Server versions before 2.2.2-5027. Attackers need valid credentials to exploit this vulnerability.
💻 Affected Systems
- Synology DNS Server
📦 What is this software?
Dns Server by Synology
⚠️ Risk & Real-World Impact
Worst Case
Complete system compromise through deletion of critical system files, leading to service disruption, data loss, or privilege escalation.
Likely Case
Targeted deletion of configuration files, logs, or application data causing service disruption or data loss.
If Mitigated
Limited impact due to proper access controls and file permissions restricting what authenticated users can delete.
🎯 Exploit Status
Exploitation requires authenticated access but path traversal vulnerabilities are typically straightforward to exploit once vectors are identified.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 2.2.2-5027 and later
Vendor Advisory: https://www.synology.com/security/advisory/Synology_SA_20_27
Restart Required: Yes
Instructions:
1. Log into DSM as administrator. 2. Open Package Center. 3. Find Synology DNS Server. 4. Click Update if available. 5. Alternatively, download the latest version from Synology's website and manually install.
🔧 Temporary Workarounds
Restrict DNS Server Access
allLimit access to the DNS Server interface to trusted networks only.
Implement Strong Authentication
allEnforce strong passwords and consider multi-factor authentication for DNS Server administrators.
🧯 If You Can't Patch
- Restrict DNS Server web interface access to specific IP addresses or VLANs only.
- Implement strict file permissions and monitor for unauthorized file deletion attempts.
🔍 How to Verify
Check if Vulnerable:
Check the installed version of Synology DNS Server in Package Center or via command line: synopkg version DNS_ServerCheck Version:
synopkg version DNS_ServerVerify Fix Applied:
Verify the installed version is 2.2.2-5027 or later in Package Center or via command line.📡 Detection & Monitoring
Log Indicators:
- Unusual file deletion events in system logs
- Multiple failed authentication attempts followed by successful login and file operations
Network Indicators:
- Unusual HTTP requests to DNS Server CGI endpoints with path traversal patterns
SIEM Query:
source="synology_dns" AND (event="file_delete" OR uri="*../*")