CVE-2021-36320
📋 TL;DR
Dell Networking X-Series switches with firmware versions before 3.0.1.8 contain an authentication bypass vulnerability. Remote attackers can forge session IDs to hijack web management sessions without credentials. This affects all organizations using vulnerable Dell X-Series networking equipment.
💻 Affected Systems
- Dell Networking X-Series switches
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Complete compromise of network infrastructure, allowing attacker to reconfigure switches, intercept traffic, create backdoors, and disrupt network operations.
Likely Case
Unauthorized access to switch management interface, enabling configuration changes, traffic monitoring, and potential lateral movement to other systems.
If Mitigated
Limited impact if switches are isolated from untrusted networks and have additional authentication layers, though risk remains if web interface is accessible.
🎯 Exploit Status
Authentication bypass vulnerabilities are typically easy to exploit once the technique is understood. No public exploit code is known, but the vulnerability is straightforward.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 3.0.1.8 or later
Vendor Advisory: https://www.dell.com/support/kbdoc/en-us/000193230/dsa-2021-191-dell-networking-x-series-security-update-for-multiple-security-vulnerabilities
Restart Required: Yes
Instructions:
1. Download firmware 3.0.1.8 or later from Dell support site. 2. Backup current configuration. 3. Upload new firmware via web interface or CLI. 4. Reboot switch to apply update. 5. Verify firmware version after reboot.
🔧 Temporary Workarounds
Disable web management interface
allDisable the vulnerable web server and use CLI (SSH/Telnet) for management instead
no ip http server
no ip http secure-server
Restrict web interface access
allLimit web management access to trusted management networks only using ACLs
ip http access-class <ACL-NUMBER>
ip http secure-server access-class <ACL-NUMBER>
🧯 If You Can't Patch
- Isolate switches from untrusted networks using VLANs and firewall rules
- Implement network segmentation to limit lateral movement if switches are compromised
🔍 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 3.0.1.8 or higher using 'show version' command📡 Detection & Monitoring
Log Indicators:
- Multiple failed login attempts followed by successful login from same IP
- Administrative configuration changes from unexpected IP addresses
- Web server access from unusual source IPs
Network Indicators:
- HTTP/HTTPS traffic to switch management interfaces from unauthorized networks
- Unusual configuration changes via web interface protocols
SIEM Query:
source_ip IN (switch_management_ips) AND (event_type='login_success' OR event_type='configuration_change') AND user_agent CONTAINS 'web_browser'