Suspicious Process from Conhost

Identifies a suspicious Conhost child process which may be an indication of code injection activity.

Rule type: eql

Rule indices:

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

Severity: high

Risk score: 73

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:

• https://modexp.wordpress.com/2018/09/12/process-injection-user-data/
• https://github.com/sbousseaden/EVTX-ATTACK-SAMPLES/blob/master/Defense%20Evasion/evasion_codeinj_odzhan_conhost_sysmon_10_1.evtx

Tags:

• Elastic
• Host
• Windows
• Threat Detection
• Defense Evasion

Version: 5

Rule authors:

• Elastic

Rule license: Elastic License v2

If enabling an EQL rule on a non-elastic-agent index (such as beats) for versions <8.2, events will not define event.ingested and default fallback for EQL rules was not added until 8.2, so you will need to add a custom pipeline to populate event.ingested to @timestamp for this rule to work.

process where event.type in ("start", "process_started") and
  process.parent.name : "conhost.exe" and
  not process.executable : ("?:\\Windows\\splwow64.exe", "?:\\Windows\\System32\\WerFault.exe", "?:\\Windows\\System32\\conhost.exe")

Framework: MITRE ATT&CKTM

• Tactic:

  • Name: Defense Evasion
  • ID: TA0005
  • Reference URL: https://attack.mitre.org/tactics/TA0005/

• Technique:

  • Name: Process Injection
  • ID: T1055
  • Reference URL: https://attack.mitre.org/techniques/T1055/