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File and Directory Discovery

Warning

This rule has been deprecated as of 2022/08/02.

Enumeration of files and directories using built-in tools. Adversaries may use the information discovered to plan follow-on activity.

Rule type: eql
Rule indices:

  • logs-endpoint.events.*
  • winlogbeat-*
  • logs-windows.*

Rule Severity: low
Risk Score: 21
Runs every:
Searches indices from: now-9m
Maximum alerts per execution: 100
References:

Tags:

  • Elastic
  • Host
  • Windows
  • Threat Detection
  • Discovery

Version: 100
Rule authors:

  • Elastic

Rule license: Elastic License v2

After successfully compromising an environment, attackers may try to gain situational awareness to plan their next steps. This can happen by running commands to enumerate network resources, users, connections, files, and installed security software.

This rule looks for three directory-listing commands in one minute, which can indicate attempts to locate valuable files, specific file types or installed programs.

  • Investigate the process execution chain (parent process tree) for unknown processes. Examine their executable files for prevalence, whether they are located in expected locations, and if they are signed with valid digital signatures.
  • Identify the user account that performed the action and whether it should perform this kind of action.
  • Investigate other alerts associated with the user/host during the past 48 hours.
  • Investigate abnormal behaviors observed using the account, such as commands executed, files created or modified, and network connections.
  • Discovery activities are not inherently malicious if they occur in isolation. As long as the analyst did not identify suspicious activity related to the user or host, such alerts can be dismissed.
  • Initiate the incident response process based on the outcome of the triage.
  • Isolate the involved hosts to prevent further post-compromise behavior.
  • Investigate credential exposure on systems compromised or used by the attacker to ensure all compromised accounts are identified. Reset passwords for these accounts and other potentially compromised credentials, such as email, business systems, and web services.
  • Run a full antimalware scan. This may reveal additional artifacts left in the system, persistence mechanisms, and malware components.
  • Determine the initial vector abused by the attacker and take action to prevent reinfection via the same vector.
  • Using the incident response data, update logging and audit policies to improve the mean time to detect (MTTD) and the mean time to respond (MTTR).
sequence by agent.id, user.name with maxspan=1m
[process where event.type in ("start", "process_started") and
  ((process.name : "cmd.exe" or process.pe.original_file_name == "Cmd.Exe") and process.args : "dir") or
    process.name : "tree.com"]
[process where event.type in ("start", "process_started") and
  ((process.name : "cmd.exe" or process.pe.original_file_name == "Cmd.Exe") and process.args : "dir") or
    process.name : "tree.com"]
[process where event.type in ("start", "process_started") and
  ((process.name : "cmd.exe" or process.pe.original_file_name == "Cmd.Exe") and process.args : "dir") or
    process.name : "tree.com"]

Framework: MITRE ATT&CK