CVE-2021-1571
📋 TL;DR
This CVE describes multiple vulnerabilities in Cisco Small Business 220 Series Smart Switches web management interface that could allow attackers to hijack user sessions, execute arbitrary commands as root, conduct XSS attacks, and perform HTML injection. Affected organizations are those using these switches with web management enabled. The vulnerabilities stem from improper authentication mechanisms.
💻 Affected Systems
- Cisco Small Business 220 Series Smart Switches
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Complete compromise of network switch allowing attacker to execute arbitrary commands as root, reconfigure network, intercept traffic, and pivot to other systems.
Likely Case
Session hijacking leading to unauthorized configuration changes, XSS attacks compromising admin credentials, and potential network disruption.
If Mitigated
Limited impact if web interface is disabled or properly segmented, though underlying vulnerabilities remain.
🎯 Exploit Status
Exploitation requires network access to web interface but no authentication. Multiple attack vectors increase likelihood of successful exploitation.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 1.2.0.6 or later
Vendor Advisory: https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-ciscosb-multivulns-Wwyb7s5E
Restart Required: Yes
Instructions:
1. Download firmware 1.2.0.6 or later from Cisco website. 2. Backup current configuration. 3. Upload new firmware via web interface or CLI. 4. Reboot switch. 5. Verify firmware version.
🔧 Temporary Workarounds
Disable web management interface
allDisable HTTP/HTTPS web interface and use only SSH or console for management
no ip http server
no ip http secure-server
Network segmentation
allRestrict access to management interface using ACLs or firewall rules
access-list 10 permit 192.168.1.0 0.0.0.255
ip http access-class 10
🧯 If You Can't Patch
- Disable web management interface completely and use SSH/console only
- Implement strict network segmentation and firewall rules to limit access to management interface
🔍 How to Verify
Check if Vulnerable:
Check firmware version via CLI: 'show version' or web interface: System > AboutCheck Version:
show version | include VersionVerify Fix Applied:
Verify firmware version is 1.2.0.6 or later using 'show version' command📡 Detection & Monitoring
Log Indicators:
- Multiple failed authentication attempts
- Unusual configuration changes
- Unexpected reboots
- New admin users
Network Indicators:
- Unusual traffic to/from switch management interface
- HTTP requests with suspicious parameters
- Traffic patterns indicating command execution
SIEM Query:
source="switch_logs" AND (event_type="config_change" OR event_type="auth_failure")