Privilege Escalation: Get Kubernetes CSR with compromised bootstrap credentials

This document describes a threat finding type in Security Command Center. Threat findings are generated by threat detectors when they detect a potential threat in your cloud resources. For a full list of available threat findings, see Threat findings index.

Overview

To escalate privilege, a potentially malicious actor queried for a certificate signing request (CSR), with the kubectl command, using compromised bootstrap credentials.

The following is an example of a command that this rule detects:

kubectl --client-certificate kubelet.crt --client-key kubelet.key --server YOUR_SERVER get csr CSR_NAME

How to respond

To respond to this finding, do the following:

Step 1: Review finding details

  1. Open the Privilege Escalation: Get Kubernetes CSR with compromised bootstrap credentials finding as directed in Reviewing findings. The details panel for the finding opens to the Summary tab.

  2. On the Summary tab, review the information in the following sections:

    • What was detected, especially the following fields:
      • Principal email: the account that made the call.
      • Method name: the method that was called.
    • Under Affected resource:
      • Resource display name: the Kubernetes cluster where the action occurred.
    • Related links, especially the following fields:
      • Cloud Logging URI: link to Logging entries.
      • MITRE ATT&CK method: link to the MITRE ATT&CK documentation.
      • Related findings: links to any related findings.

Step 2: Check logs

If the method name, which you noted in the Method name field in the finding details, is a GET method, do the following:

  1. On the Summary tab of the finding details in the Google Cloud console, go to Logs Explorer by clicking the link in the Cloud Logging URI field.
  2. Check the value in the protoPayload.resourceName field to identify the specific certificate signing request.

Step 3: Research attack and response methods

  1. Review MITRE ATT&CK framework entries for this finding type: Privilege Escalation.
  2. If the specific CSR is available in the log entry, investigate the sensitivity of the certificate and whether the action was warranted.
  3. To develop a response plan, combine your investigation results with MITRE research.

What's next