LoFP LoFP / there is a potential for false positives if the \"env\" or \"printenv\" commands are used for legitimate purposes, such as debugging or troubleshooting. it is important to investigate any alerts generated by this rule to determine if they are indicative of malicious activity or part of legitimate container activity.

Techniques

Sample rules

Environment Variable Enumeration Detected via Defend for Containers

Description

This rule detects the execution of the “env” or “printenv” commands inside a container. The “env” command is used to display all the environment variables for the current shell, and the “printenv” command is used to print the values of environment variables. These commands are used to enumerate the environment variables of the container, which can be used by an adversary to gain information about the container and the services running inside it.

Detection logic

process where host.os.type == "linux" and event.type == "start" and event.action == "exec" and (
  process.name in ("env", "printenv") or
  (
    /* Account for tools that execute utilities as a subprocess, in this case the target utility name will appear as a process arg */
    process.name in ("bash", "dash", "sh", "tcsh", "csh", "zsh", "ksh", "fish", "busybox") and
    process.args in (
      "env", "/bin/env", "/usr/bin/env", "/usr/local/bin/env",
      "printenv", "/bin/printenv", "/usr/bin/printenv", "/usr/local/bin/printenv"
    ) and
    /* default exclusion list to not FP on default multi-process commands */
    not process.args in (
      "which", "/bin/which", "/usr/bin/which", "/usr/local/bin/which",
      "man", "/bin/man", "/usr/bin/man", "/usr/local/bin/man",
      "chmod", "/bin/chmod", "/usr/bin/chmod", "/usr/local/bin/chmod",
      "chown", "/bin/chown", "/usr/bin/chown", "/usr/local/bin/chown"
    )
  )
) and
process.interactive == true and container.id like "*"