CVE-2021-23196
📋 TL;DR
This vulnerability allows attackers to bypass authentication and gain unauthorized access to Agilia Link+ web applications by manipulating client-side authentication attributes. It affects all users of Agilia Link+ version 3.0 where the web application is exposed. The flaw stems from insufficient protection of authentication mechanisms implemented exclusively on the client side.
💻 Affected Systems
- Agilia Link+
📦 What is this software?
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⚠️ Risk & Real-World Impact
Worst Case
Complete compromise of the Agilia Link+ system allowing unauthorized access to sensitive medical data, configuration changes, and potential disruption of medical device operations.
Likely Case
Unauthorized access to patient data, system configuration, and potential manipulation of medical device settings or treatment parameters.
If Mitigated
Limited impact with proper network segmentation and access controls, though authentication bypass remains possible.
🎯 Exploit Status
Client-side authentication bypass typically requires minimal technical skill using browser developer tools or proxy manipulation
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Contact vendor for specific patched version
Vendor Advisory: https://www.cisa.gov/uscert/ics/advisories/icsma-21-355-01
Restart Required: Yes
Instructions:
1. Contact Fresenius Kabi (vendor) for patched version
2. Schedule maintenance window for medical device updates
3. Apply vendor-provided patch following medical device update protocols
4. Verify authentication now requires server-side validation
🔧 Temporary Workarounds
Network Segmentation
allIsolate Agilia Link+ systems from untrusted networks
Access Control Lists
allImplement strict firewall rules limiting access to authorized IPs only
🧯 If You Can't Patch
- Implement network segmentation to isolate Agilia Link+ from all untrusted networks
- Deploy web application firewall with authentication bypass detection rules
🔍 How to Verify
Check if Vulnerable:
Test if authentication tokens or session data can be manipulated client-side without server validationCheck Version:
Check device interface or contact vendor for version informationVerify Fix Applied:
Verify that authentication now requires server-side validation and client-side manipulation no longer works📡 Detection & Monitoring
Log Indicators:
- Unauthorized access attempts
- Authentication bypass patterns
- Multiple failed login attempts followed by successful access
Network Indicators:
- Unusual access patterns to Agilia Link+ web interface
- Traffic from unauthorized IP addresses
SIEM Query:
source="agilia-link" AND (event_type="auth_bypass" OR status="200" AND method="POST" AND uri="/login" AND user_agent CONTAINS "curl" OR "python")