Microsoft Open Management Infrastructure (OMI) Privilege Escalation and Authentication Bypass (CVE-2021-38648)
Executive & SecOps Summary
SECOPS ASSESSMENTMicrosoft Open Management Infrastructure (OMI) versions prior to 1.6.8-1, commonly deployed in Azure Linux environments
Remote or local attackers can bypass authentication to execute arbitrary commands with root privileges, leading to full system compromise
Immediately upgrade OMI to version 1.6.8-1 or higher, and restrict access to OMI ports (5985, 5986)
Affected Products & Version Scope
Remediation & Live Workaround Commands
PATCH & WORKAROUND1. Official Patch & Version Upgrade Commands
Update the OMI package to the latest secure version (1.6.8-1 or higher) using the system package manager.
# For Debian/Ubuntu-based systems
sudo apt-get update && sudo apt-get install --only-upgrade omi -y
# For RHEL/CentOS-based systems
sudo yum update omi -y2. Temporary Workaround & Hardening Configuration
If patching cannot be applied immediately, restrict network access to the OMI ports (5985, 5986) using host-based firewalls.
# Block OMI ports using iptables
sudo iptables -A INPUT -p tcp --dport 5985 -j DROP
sudo iptables -A INPUT -p tcp --dport 5986 -j DROP
# Block OMI ports using ufw
sudo ufw deny proto tcp from any to any port 5985,5986
sudo ufw reload3. Log Audit & IoC Verification Commands
Verify the installed OMI version and check if the OMI service is listening on external ports.
# Check OMI version
if [ -f /opt/omi/bin/omiserver ]; then
/opt/omi/bin/omiserver -v
else
echo 'OMI is not installed or not in the default path.'
fi
# Check if OMI ports are listening
sudo ss -tulnp | grep -E '5985|5986'Detect Container Escape & Privilege Escalation Across Your Kubernetes Fleet
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Technical Root Cause & Exploitation Mechanics
1. Vulnerability Overview & Root Cause
This vulnerability, widely known as 'OMIGOD', is a critical authentication bypass and elevation of privilege vulnerability in Microsoft's Open Management Infrastructure (OMI). OMI is an open-source CIM management server for Linux systems, frequently pre-installed and automatically deployed in Azure Linux Virtual Machines. The root cause lies in a flaw within the OMI authentication handler: when an HTTP/HTTPS request is received with a missing or empty 'Authorization' header, the server incorrectly defaults to treating the request as pre-authenticated with administrative privileges.
2. Exploitation Mechanics & Attack Scenario
An attacker can exploit this vulnerability by sending a specially crafted SOAP request over HTTP/HTTPS to the OMI listening ports (typically 5985 or 5986). By omitting the 'Authorization' header from the request, the OMI server processes the command under the context of the privileged 'root' user. This allows unauthenticated remote attackers to execute arbitrary code (RCE) if the ports are exposed to the internet, or local users to escalate privileges to root (LPE).
3. Infrastructure & Business Impact
This vulnerability is actively exploited in the wild and is cataloged in CISA's Known Exploited Vulnerabilities (KEV). Given OMI's silent deployment across millions of Azure Linux VMs, the business impact is severe. Successful exploitation allows attackers to gain full administrative control over cloud infrastructure, enabling lateral movement, data exfiltration, ransomware deployment, and unauthorized resource utilization.
Official Vendor Advisories & References
Open Management Infrastructure Elevation of Privilege Vulnerability
Frequently Asked SecOps Questions (CVE-2021-38648)
FAQQ1. How critical is CVE-2021-38648 and is it actively exploited in the wild?
CVE-2021-38648 is rated CVSS 7.8 (HIGH) with a 30-day EPSS exploitation probability of 11.4%. It is listed in the CISA Known Exploited Vulnerabilities (KEV) catalog, requiring immediate emergency remediation.
Q2. Which vendors and products are affected by CVE-2021-38648?
Primary impacted vendors include microsoft across open management infrastructure, omi. Scope summary: Microsoft Open Management Infrastructure (OMI) versions prior to 1.6.8-1
Q3. What temporary mitigations or workarounds exist for CVE-2021-38648 before patching?
[Mitigation] Immediately upgrade OMI to version 1.6.8-1 or higher, and restrict access to OMI ports (5985, 5986) Follow the CLI remediation commands and interactive SecOps checklist on this page to restrict exposure prior to your maintenance window.
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