Unusual Network Connection via DllHost

Identifies unusual instances of dllhost.exe making outbound network connections. This may indicate adversarial Command and Control activity.

Rule type: eql

Rule indices:

winlogbeat-*
logs-endpoint.events.process-*
logs-endpoint.events.network-*
logs-windows.sysmon_operational-*

Severity: medium

Risk score: 47

Runs every: 5m

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

Maximum alerts per execution: 100

References:

Tags:

Domain: Endpoint
OS: Windows
Use Case: Threat Detection
Tactic: Defense Evasion
Data Source: Elastic Defend
Data Source: Sysmon

Version: 207

Rule authors:

Elastic

Rule license: Elastic License v2

Rule query

edit

sequence by host.id, process.entity_id with maxspan=1m
  [process where host.os.type == "windows" and event.type == "start" and process.name : "dllhost.exe" and process.args_count == 1]
  [network where host.os.type == "windows" and process.name : "dllhost.exe" and
   not cidrmatch(destination.ip, "10.0.0.0/8", "127.0.0.0/8", "169.254.0.0/16", "172.16.0.0/12", "192.0.0.0/24",
    "192.0.0.0/29", "192.0.0.8/32", "192.0.0.9/32", "192.0.0.10/32", "192.0.0.170/32", "192.0.0.171/32", "192.0.2.0/24",
    "192.31.196.0/24", "192.52.193.0/24", "192.168.0.0/16", "192.88.99.0/24", "224.0.0.0/4", "100.64.0.0/10",
    "192.175.48.0/24", "198.18.0.0/15", "198.51.100.0/24", "203.0.113.0/24", "240.0.0.0/4", "::1", "FE80::/10",
    "FF00::/8")]

Framework: MITRE ATT&CK^TM

Tactic:
- Name: Defense Evasion
- ID: TA0005
- Reference URL: https://attack.mitre.org/tactics/TA0005/
Technique:
- Name: System Binary Proxy Execution
- ID: T1218
- Reference URL: https://attack.mitre.org/techniques/T1218/

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