CVE-2021-21505
📋 TL;DR
CVE-2021-21505 is a critical vulnerability in Dell EMC Integrated System for Microsoft Azure Stack Hub where an undocumented default iDRAC account exists with known credentials. Remote unauthenticated attackers can use these credentials to gain root privileges on affected systems. Organizations running Dell EMC Integrated System for Microsoft Azure Stack Hub versions 1906 through 2011 are affected.
💻 Affected Systems
- Dell EMC Integrated System for Microsoft Azure Stack Hub
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Complete system compromise with root access, allowing attackers to install persistent malware, exfiltrate sensitive data, disrupt Azure Stack Hub operations, and pivot to other network resources.
Likely Case
Unauthorized administrative access to iDRAC interface leading to system configuration changes, service disruption, and potential credential harvesting from the compromised system.
If Mitigated
Limited impact with proper network segmentation and access controls preventing external access to iDRAC interfaces.
🎯 Exploit Status
Exploitation requires only knowledge of the default credentials and network access to iDRAC interface. No special tools or advanced skills needed.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Apply Dell EMC Integrated System for Microsoft Azure Stack Hub update as specified in DSA-2021-020
Restart Required: Yes
Instructions:
1. Review Dell advisory DSA-2021-020. 2. Download and apply the security update from Dell support portal. 3. Restart affected systems as required. 4. Verify the undocumented account has been removed.
🔧 Temporary Workarounds
Network Segmentation
allRestrict network access to iDRAC interfaces using firewall rules to only allow connections from trusted management networks.
Change Default Credentials
allIf unable to patch immediately, change iDRAC credentials and disable any default accounts.
🧯 If You Can't Patch
- Implement strict network access controls to isolate iDRAC interfaces from untrusted networks
- Monitor iDRAC access logs for unauthorized login attempts and implement alerting
🔍 How to Verify
Check if Vulnerable:
Check system version against affected range (1906-2011) and attempt to authenticate to iDRAC using known default credentials if authorized for testing.Check Version:
Check Azure Stack Hub version through administrator portal or PowerShell: Get-AzureStackStampInformationVerify Fix Applied:
After patching, verify the undocumented default account no longer exists by attempting authentication with known credentials (if authorized) and checking iDRAC user accounts.📡 Detection & Monitoring
Log Indicators:
- Failed or successful authentication attempts to iDRAC from unexpected sources
- iDRAC configuration changes from unknown users
- Multiple authentication attempts with default credentials
Network Indicators:
- Unexpected connections to iDRAC ports (typically 443, 623, 5900)
- Traffic patterns indicating iDRAC brute force attempts
SIEM Query:
source="idrac" AND (event_type="authentication" OR event_type="login") AND (user="default" OR user="root" OR result="failure")🔗 References
- https://www.dell.com/support/kbdoc/en-us/000186008/dsa-2021-020-dell-emc-integrated-system-for-microsoft-azure-stack-hub-security-update-for-an-idrac-undocumented-account-vulnerability
- https://www.dell.com/support/kbdoc/en-us/000186008/dsa-2021-020-dell-emc-integrated-system-for-microsoft-azure-stack-hub-security-update-for-an-idrac-undocumented-account-vulnerability
