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Remote System Discovery Commands

Elastic Stack Serverless Security

Discovery of remote system information using built-in commands, which may be used to move laterally.

Rule type: eql

Rule indices:

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

Severity: low

Risk score: 21

Runs every: 5m

Searches indices from: now-9m (https://www.elastic.co/guide/en/elasticsearch/reference/current/common-options.html#date-math[Date Math format], see also Additional look-back time)

Maximum alerts per execution: 100

References: None

Tags:

  • Elastic
  • Host
  • Windows
  • Threat Detection
  • Discovery
  • has_guide

Version: 101

Rule authors:

  • Elastic

Rule license: Elastic License v2

Investigation guide

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 the execution of the arp or nbstat utilities to enumerate remote systems in the environment,
which is useful for attackers to identify lateral movement targets.

  • 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 any abnormal account behavior, such as command executions, file creations or modifications, 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 through 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).

Rule query

process where event.type == "start" and
  ((process.name : "nbtstat.exe" and process.args : ("-n", "-s")) or
  (process.name : "arp.exe" and process.args : "-a"))

Framework: MITRE ATT&CKTM