Unusual Network Connection via DllHost

edit

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.*
  • 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

References:

Tags:

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

Version: 101 (version history)

Added (Elastic Stack release): 7.14.0

Last modified (Elastic Stack release): 8.5.0

Rule authors: Elastic

Rule license: Elastic License v2

Rule query

edit
sequence by host.id, process.entity_id with maxspan=1m [process
where event.type == "start" and process.name : "dllhost.exe" and
process.args_count == 1] [network where 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")]

Threat mapping

edit

Framework: MITRE ATT&CKTM

Rule version history

edit
Version 101 (8.5.0 release)
  • Updated query, changed from:

    sequence by host.id, process.entity_id with maxspan=1m [process
    where event.type in ("start", "process_started") and process.name :
    "dllhost.exe" and process.args_count == 1] [network where
    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")]
Version 4 (8.4.0 release)
  • Formatting only
Version 2 (8.2.0 release)
  • Formatting only