CVE-2020-25842
📋 TL;DR
This vulnerability in NHIServiSignAdapter allows remote attackers to access arbitrary files without proper authentication due to insufficient path validation in the encryption function. Systems using vulnerable versions of NHIServiSignAdapter are affected, potentially exposing sensitive data.
💻 Affected Systems
- NHIServiSignAdapter
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Complete system compromise through sensitive file disclosure (configuration files, credentials, private keys) leading to lateral movement and data exfiltration.
Likely Case
Unauthorized access to sensitive files containing configuration data, user information, or system details that could facilitate further attacks.
If Mitigated
Limited impact with proper network segmentation and file system permissions preventing access to critical system files.
🎯 Exploit Status
The vulnerability involves path traversal without authentication, making exploitation straightforward for attackers with network access to the service.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Not specified in provided references - check vendor advisory
Vendor Advisory: https://www.twcert.org.tw/tw/cp-132-4270-72392-1.html
Restart Required: Yes
Instructions:
1. Contact NHIServiSignAdapter vendor for security patches. 2. Apply the patch following vendor instructions. 3. Restart the NHIServiSignAdapter service. 4. Verify the fix prevents arbitrary file access.
🔧 Temporary Workarounds
Network Isolation
allRestrict network access to NHIServiSignAdapter service to only trusted systems
Use firewall rules to block external access to NHIServiSignAdapter ports
File System Permissions
windowsLimit file system access for NHIServiSignAdapter service account
Set restrictive permissions on sensitive directories using OS-specific ACL commands
🧯 If You Can't Patch
- Implement strict network segmentation to isolate NHIServiSignAdapter from untrusted networks
- Apply principle of least privilege to NHIServiSignAdapter service account file system access
🔍 How to Verify
Check if Vulnerable:
Test if NHIServiSignAdapter service allows file path traversal by attempting to access files outside intended directories via the encryption functionCheck Version:
Check NHIServiSignAdapter version through service properties or vendor documentationVerify Fix Applied:
Verify that path traversal attempts are blocked and only validated file paths are processed📡 Detection & Monitoring
Log Indicators:
- Unusual file access patterns in NHIServiSignAdapter logs
- Multiple failed path validation attempts
- Access to system files via NHIServiSignAdapter service
Network Indicators:
- Unexpected connections to NHIServiSignAdapter ports from untrusted sources
- Traffic patterns indicating file enumeration
SIEM Query:
source="NHIServiSignAdapter" AND (event_type="file_access" OR event_type="encryption_request") AND file_path CONTAINS ".."