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Elastic Docs ›Elastic Security Solution [8.5] ›Detections and alerts ›Prebuilt rule reference

Windows Network Enumeration

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Windows Network Enumeration

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Identifies attempts to enumerate hosts in a network using the built-in Windows net.exe tool.

Rule type: eql

Rule indices:

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

Severity: medium

Risk score: 47

Runs every: 5 minutes

Searches indices from: now-9m (Date Math format, see also Additional look-back time)

Maximum alerts per execution: 100

Tags:

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

Version: 101 (version history)

Added (Elastic Stack release): 7.11.0

Last modified (Elastic Stack release): 8.5.0

Rule authors: Elastic

Rule license: Elastic License v2

Investigation guide

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## Triage and analysis

### Investigating Windows Network Enumeration

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 `net` utility to enumerate servers in the environment that hosts shared drives
or printers. This information is useful to attackers as they can identify targets for lateral movements and search for
valuable shared data.

#### Possible investigation steps

- 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.

### False positive analysis

- 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.

### Response and remediation

- 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

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process where event.type == "start" and ((process.name : "net.exe"
or process.pe.original_file_name == "net.exe") or ((process.name :
"net1.exe" or process.pe.original_file_name == "net1.exe") and
not process.parent.name : "net.exe")) and (process.args : "view" or
(process.args : "time" and process.args : "\\\\*")) /* expand when
ancestry is available and not descendant of [process where
event.type == "start" and process.name : "cmd.exe" and
((process.parent.name : "userinit.exe") or
(process.parent.name : "gpscript.exe") or
(process.parent.name : "explorer.exe" and
process.args : "C:\\*\\Start Menu\\Programs\\Startup\\*.bat*"))] */

Threat mapping

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Framework: MITRE ATT&CKTM

Rule version history

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Version 101 (8.5.0 release)

  • Updated query, changed from:

    process where event.type in ("start", "process_started") and
((process.name : "net.exe" or process.pe.original_file_name ==
"net.exe") or ((process.name : "net1.exe" or
process.pe.original_file_name == "net1.exe") and not
process.parent.name : "net.exe")) and (process.args : "view" or
(process.args : "time" and process.args : "\\\\*")) /* expand when
ancestry is available and not descendant of [process where
event.type == ("start", "process_started") and process.name :
"cmd.exe" and ((process.parent.name :
"userinit.exe") or (process.parent.name :
"gpscript.exe") or (process.parent.name :
"explorer.exe" and process.args :
"C:\\*\\Start Menu\\Programs\\Startup\\*.bat*"))] */
Version 8 (8.4.0 release)
  • Formatting only
Version 6 (8.3.0 release)
  • Formatting only
Version 5 (8.2.0 release)
  • Formatting only
Version 4 (7.15.0 release)

  • Updated query, changed from:

    process where event.type in ("start", "process_started") and
((process.name : "net.exe" or process.pe.original_file_name ==
"net.exe") or ((process.name : "net1.exe" or
process.pe.original_file_name == "net1.exe") and not
process.parent.name : "net.exe")) and (process.args : "view" or
(process.args : "time" and process.args : "\\\\*")) /* expand when
ancestory is available and not descendant of [process where
event.type == ("start", "process_started") and process.name :
"cmd.exe" and ((process.parent.name :
"userinit.exe") or (process.parent.name :
"gpscript.exe") or (process.parent.name :
"explorer.exe" and process.args :
"C:\\*\\Start Menu\\Programs\\Startup\\*.bat*"))] */
Version 3 (7.12.0 release)
  • Formatting only
Version 2 (7.11.2 release)
  • Formatting only
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