DNS Enumeration Detected via Defend for Containers

process where host.os.type == "linux" and event.type == "start" and event.action == "exec" and
container.id like "*" and 
(
  /* getent hosts is often used without a target arg */
  (process.name == "getent" and process.args == "hosts") or

  /* explicit DNS query tools */
  (
    process.name in ("nslookup", "dig", "host") 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 (
        "nslookup", "/bin/nslookup", "/usr/bin/nslookup", "/usr/local/bin/nslookup",
        "dig", "/bin/dig", "/usr/bin/dig", "/usr/local/bin/dig",
        "host", "/bin/host", "/usr/bin/host", "/usr/local/bin/host"
      ) 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.args like~ (
    "kubernetes.default",
    "kubernetes",
    "*.svc",
    "*.svc.cluster.local",
    "*.cluster.local"
  )
)

False Positives

• ⚠ There is a potential for false positives if the DNS enumeration tools 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.