CVE-2021-28805
📋 TL;DR
This vulnerability involves sensitive information exposure in QNAP switch firmware source code, allowing attackers to read application data. It affects QNAP QSS firmware on specific switch models before certain versions. Attackers could potentially access confidential information if they can exploit this flaw.
💻 Affected Systems
- QSW-M2108-2C
- QSW-M2108-2S
- QSW-M2108R-2C
- QSW-M408
📦 What is this software?
Qss by Qnap
Qss by Qnap
⚠️ Risk & Real-World Impact
Worst Case
Attackers gain access to sensitive application data, potentially including credentials, configuration details, or other confidential information stored in the source code.
Likely Case
Information disclosure allowing attackers to gather intelligence about the system configuration and potentially find additional attack vectors.
If Mitigated
Limited impact with proper network segmentation and access controls preventing external attackers from reaching vulnerable systems.
🎯 Exploit Status
Information disclosure vulnerabilities typically have low exploitation complexity once the attack vector is identified.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: QSS 1.0.3 build 20210505 for QSW-M2108-2C, QSW-M2108-2S, QSW-M2108R-2C; QSS 1.0.12 build 20210506 for QSW-M408
Vendor Advisory: https://www.qnap.com/zh-tw/security-advisory/qsa-21-24
Restart Required: Yes
Instructions:
1. Log into QNAP switch management interface. 2. Navigate to System > Firmware Update. 3. Check for updates and install the latest firmware version. 4. Reboot the switch after installation completes.
🔧 Temporary Workarounds
Network Segmentation
allIsolate affected switches from untrusted networks and limit access to management interfaces.
🧯 If You Can't Patch
- Implement strict network access controls to limit who can reach the switch management interfaces
- Monitor network traffic to/from affected switches for unusual access patterns
🔍 How to Verify
Check if Vulnerable:
Check the firmware version in the QNAP switch web interface under System > Firmware UpdateCheck Version:
No CLI command available; check via web interface at System > Firmware UpdateVerify Fix Applied:
Verify firmware version matches or exceeds the patched versions listed in the advisory📡 Detection & Monitoring
Log Indicators:
- Unusual access to source code files or application data
- Multiple failed attempts to access sensitive paths
Network Indicators:
- Unusual HTTP requests to switch management interface
- Traffic patterns indicating source code scraping
SIEM Query:
source_ip accessing switch_management_interface AND (uri contains ".php" OR uri contains ".js" OR uri contains source_code_patterns)