Unexpected Child Shell

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

Cloud Run Threat Detection observed a process that unexpectedly spawned a child shell process. This event might indicate that an attacker is trying to abuse shell commands and scripts.

Detection service

Cloud Run Threat Detection

How to respond

To respond to this finding, do the following:

Review finding details

  1. Open the Unexpected Child Shell finding as directed in Reviewing findings. Review the details on the Summary and JSON tabs.

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

    • What was detected, especially the following fields:
      • Parent process: the process that unexpectedly created the child shell process
      • Child process: the child shell process
      • Arguments: the arguments provided to the child shell process binary
      • Environment variables: the environment variables of the child shell process binary
      • Containers: the name of the container
      • Containers URI: the image URI of the container
    • Affected resource, especially the following fields:
      • Resource display name: the name of the affected resource.
      • Resource full name: the full resource name of the affected Cloud Run resource
    • Related links, especially the following field:
      • VirusTotal indicator: link to the VirusTotal analysis page

  3. On the JSON tab, note the following fields:

    • processes: an array containing all processes related to the finding. This array includes the child shell process and the parent process.
    • resource:
      • project_display_name: name of the project that contains the assets.

  4. Look for related findings that occurred at a similar time for the affected container. Such findings might indicate that this activity was malicious, instead of a failure to follow best practices.

  5. Review the settings of the affected container.

  6. Check the logs for the affected container.

Research attack and response methods

  1. Review the MITRE ATT&CK framework entry for this finding type: Command and Scripting Interpreter: Unix Shell.
  2. Check the SHA-256 hash value for the binary flagged as malicious on VirusTotal by clicking the link in VirusTotal indicator. VirusTotal is an Alphabet-owned service that provides context on potentially malicious files, URLs, domains, and IP addresses.
  3. To develop a response plan, combine your investigation results with the MITRE research and VirusTotal analysis.

Implement your response

For response recommendations, see Respond to Cloud Run threat findings.

What's next