CVE-2020-26062
📋 TL;DR
This vulnerability in Cisco Integrated Management Controller (IMC) allows unauthenticated remote attackers to enumerate valid usernames by analyzing differences in authentication responses. Attackers can identify administrative accounts to use in subsequent attacks. Organizations using vulnerable Cisco IMC versions are affected.
💻 Affected Systems
- Cisco Integrated Management Controller (IMC)
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Attackers identify administrative usernames, then use credential stuffing or brute force attacks to gain administrative access, potentially compromising the entire management infrastructure.
Likely Case
Attackers enumerate valid usernames and use them in targeted phishing or credential stuffing attacks against the identified accounts.
If Mitigated
With proper network segmentation and monitoring, enumeration attempts are detected and blocked before attackers can use the information effectively.
🎯 Exploit Status
The vulnerability involves sending authentication requests and analyzing response differences, which is relatively simple to automate.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Multiple fixed versions depending on specific product - check Cisco advisories
Vendor Advisory: https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-cimc-auth-zWkppJxL
Restart Required: Yes
Instructions:
1. Identify affected Cisco IMC firmware versions. 2. Download and apply appropriate firmware updates from Cisco. 3. Reboot affected systems after patching. 4. Verify the fix by testing authentication response behavior.
🔧 Temporary Workarounds
Network Segmentation
allRestrict access to Cisco IMC interfaces to trusted management networks only
Access Control Lists
allImplement strict firewall rules to limit which IP addresses can access Cisco IMC management interfaces
🧯 If You Can't Patch
- Implement strict network segmentation to isolate Cisco IMC interfaces from untrusted networks
- Enable detailed logging and monitoring for authentication attempts and implement alerting for enumeration patterns
🔍 How to Verify
Check if Vulnerable:
Check Cisco IMC firmware version via web interface or CLI and compare against patched versions in Cisco advisoriesCheck Version:
From Cisco IMC CLI: show version or check via web interface under Administration > Controller ManagementVerify Fix Applied:
Test authentication responses - fixed versions should not leak username validity information through response differences📡 Detection & Monitoring
Log Indicators:
- Multiple failed authentication attempts from single source
- Authentication attempts with non-existent usernames
- Pattern of authentication requests with incremental username variations
Network Indicators:
- Unusual volume of authentication requests to Cisco IMC interfaces
- Authentication traffic from unexpected source IPs
SIEM Query:
source="cimc" AND (event_type="authentication_failure" OR event_type="authentication_attempt") | stats count by src_ip, username | where count > threshold🔗 References
- https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-cimc-auth-zWkppJxL
- https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-cimc-enum-CyheP3B7
- https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-vmanx3-vrZbOqqD
- https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-vsoln-arbfile-gtsEYxns
- https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-webex-teams-xss-zLW9tD3
