Update: On September 16, 2021, Microsoft released an updated OMS agent (v1.13.40-0) that addresses these vulnerabilities. You can download the updated version from Microsoft's GitHub repo here. In response, our team is updating the pre-built insight in InsightCloudSec to specifically look for versions of the OMS agent that are older than v1.13.40-0.

On September 14, 2021, security researchers disclosed new vulnerabilities in Microsoft Azure's implementation of Open Management Interface (OMI), with one critical unauthorized remote code execution vulnerability ranked 9.8 (CVSS 3.0).

OMI is pre-installed into Azure Linux VM instances as the byproduct of enabling certain logging, reporting, and host management options from the cloud provider’s user interface and APIs. OMI is most commonly used to manage desired-state configuration and is the Linux/Unix equivalent of Windows Management Instrumentation and Remote Management (WMI/WinRM). It normally allows administrators to remotely manage the state of systems including logging and configuration settings.

The specific remote code execution OMI vulnerability, nicknamed “OMIGOD,” could allow an attacker to gain remote access to Linux machines hosted on Azure via TCP ports 1270, 5985, and 5986. Once they have remote access, the attacker could theoretically escalate privileges, move laterally across the environment, and remotely execute code as root, allowing them to locate and exfiltrate sensitive data within the Azure environment.

Notably, while the vulnerability does allow for remote code execution (RCE) in the most severe cases, by default these services are firewalled off. Proof-of-concept exploit code is readily available, and exploitation in the wild is likely. As of publication, Shodan shows nearly 2.5 million hosts with the affected ports open to the public internet and at risk, including hosts in the IP space for most cloud providers.

Four separate CVEs have been identified but have not been submitted to MITRE as of publishing: CVE-2021-38647, CVE-2021-38648, CVE-2021-38645, and CVE-2021-38649. A fix to the vulnerable OMI library was made available (v1.6.8-1) on September 8 and requires end users to patch their Linux instances directly.  

As soon as the vulnerability was announced, our customer success and engineering teams quickly came together to understand how InsightCloudSec which provides continuous monitoring, reporting, and automated remediation of security issues in public cloud environments could help our customers identify signs of this vulnerability in their Azure environments and quickly remediate the potential risk.

Identifying Azure’s OMI vulnerability

This morning, just one day after the disclosure of this vulnerability, InsightCloudSec released an update (version 21.6.4) to all customers that includes a pre-built Insight that automatically identifies any Azure Virtual Machines in a running state that have the aforementioned TCP ports exposed to the public internet along with an associated public IP.

While native Microsoft Azure Firewall services should provide a layer of protection against this vulnerability, we strongly encourage customers to leverage this Insight to identify potential attack vectors and remediate accordingly.

As you can see in the screenshot above, InsightCloudSec is now able to easily identify virtual machines across all of your Azure subscriptions from a single view. You can build notification workflows around the findings that this Insight identifies and take corrective action to close this attack vector.

Remediating Azure’s OMI vulnerability

All of our Insights include the ability to enable remediation workflows. This capability is extremely powerful and provides customers with choices of how to remediate across different areas of their cloud footprint. With a few clicks, an automation workflow can be put in place to not only remediate the current findings but also prevent misconfigurations that could be introduced in the future. It does all of this using our near real-time data collection capabilities.

Leveraging the Create Bot option above allows the user to define the scope and desired remediation steps. For this particular issue we recommend that customers use the following workflow:

  • Flagging the resource as non-compliant
  • Creating a ticket to have the vulnerability addressed (JIRA, ServiceNow, etc.)
  • Sending a notification to the resource owner or technical point of contact that manages the Azure subscription (Slack, MS Teams, Email, etc.)
  • Optional: cleaning up offending security groups by removing the affected ports from their rules

Looking ahead

Misconfigurations and vulnerabilities such as these continue to be one of the most prevalent attack vectors for malicious users to take advantage of. We recently released a Cloud Misconfiguration Report that highlights the risk that cloud misconfigurations pose to organizations.

The rapid innovation of public clouds will continue to require both cloud security vendors and independent security researchers to collaborate and to proactively hunt for security issues and attack vectors across the Cloud Service Provider (CSP) landscape. This won’t be the last issue we see, and it’s a joint effort across all vendors that participate in this exciting space to help our customers consume these public cloud providers with peace of mind.

As these cloud security disclosures continue to increase in frequency, the speed and efficiency at which security teams can remediate the associated vulnerabilities will become absolutely critical to minimizing risk in complex cloud environments. We’re excited that our customers can quickly gain visibility to the parts of their Azure footprint that are susceptible to this vulnerability, and also have the power to continuously remediate the presence of the misconfiguration both now and in the future.

Want to learn more about the findings from our research team's 2021 Cloud Misconfigurations Report? Join our upcoming webinar to hear directly from those team members about the biggest factors that led to cloud breaches last year.

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