CVE-2021-27408
📋 TL;DR
This vulnerability allows attackers to read memory beyond intended boundaries in Welch Allyn medical device management tools, potentially leaking sensitive information. If chained with an out-of-bounds write vulnerability, it could lead to arbitrary code execution. Affected systems include Welch Allyn medical devices and management software across multiple product lines.
💻 Affected Systems
- Welch Allyn Service Tool
- Welch Allyn Connex Device Integration Suite - Network Connectivity Engine (NCE)
- Welch Allyn Software Development Kit (SDK)
- Welch Allyn Connex Central Station (CS)
- Welch Allyn Service Monitor
- Welch Allyn Connex Vital Signs Monitor (CVSM)
- Welch Allyn Connex Integrated Wall System (CIWS)
- Welch Allyn Connex Spot Monitor (CSM)
- Welch Allyn Spot Vital Signs 4400 Device
- Welch Allyn Spot 4400 Vital Signs Extended Care Device
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Arbitrary code execution leading to complete system compromise, patient data theft, or disruption of medical device functionality.
Likely Case
Information disclosure exposing sensitive medical data or system information that could facilitate further attacks.
If Mitigated
Limited impact with proper network segmentation and access controls preventing exploitation attempts.
🎯 Exploit Status
Requires chaining with another vulnerability for code execution. Medical device vulnerabilities often have limited public exploit development due to specialized nature.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Welch Allyn Service Tool: v1.10+, Welch Allyn Connex NCE: v5.3+, Welch Allyn SDK: v3.2+, Welch Allyn CS: v1.8.6+, Welch Allyn Service Monitor: v1.7.0.0+, Welch Allyn CVSM: v2.43.02+, Welch Allyn CIWS: v2.43.02+, Welch Allyn CSM: v1.52+, Welch Allyn Spot 4400: v1.11.00+
Vendor Advisory: https://us-cert.cisa.gov/ics/advisories/icsma-21-152-01
Restart Required: Yes
Instructions:
1. Contact Welch Allyn for updated firmware/software. 2. Apply patches according to vendor instructions. 3. Restart affected devices. 4. Verify patch installation.
🔧 Temporary Workarounds
Network Segmentation
allIsolate medical devices on separate network segments with strict access controls.
Access Control Restrictions
allImplement strict authentication and authorization controls for medical device management interfaces.
🧯 If You Can't Patch
- Implement strict network segmentation to isolate medical devices from general network traffic
- Deploy intrusion detection systems monitoring for anomalous access to medical device management interfaces
🔍 How to Verify
Check if Vulnerable:
Check device/software version against affected versions list. Contact Welch Allyn support for vulnerability assessment tools.Check Version:
Device/software specific - consult Welch Allyn documentation for version checking procedures.Verify Fix Applied:
Verify installed version matches or exceeds patched versions listed in vendor advisory.📡 Detection & Monitoring
Log Indicators:
- Unusual access patterns to medical device management interfaces
- Multiple failed authentication attempts
- Unexpected device reboots or configuration changes
Network Indicators:
- Anomalous network traffic to/from medical device management ports
- Unexpected protocol usage on medical device interfaces
SIEM Query:
source_ip IN (medical_device_subnets) AND (event_type='authentication_failure' OR event_type='configuration_change')