New

The executive guide to generative AI

Read more

Unusual Network Connection via RunDLL32

edit

Identifies unusual instances of rundll32.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: 10 (version history)

Added (Elastic Stack release): 7.6.0

Last modified (Elastic Stack release): 7.14.0

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 in ("start", "process_started") and process.name :
"rundll32.exe" and process.args_count == 1] [network where
process.name : "rundll32.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 10 (7.14.0 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 :
    "rundll32.exe" and process.args_count == 1] [network where
    process.name : "rundll32.exe" and not cidrmatch(destination.ip,
    "10.0.0.0/8", "172.16.0.0/12", "192.168.0.0/16", "127.0.0.0/8",
    "FE80::/10", "::1/128")]
Version 9 (7.13.0 release)
  • Updated query, changed from:

    sequence by host.id, process.entity_id with maxspan=1m [process
    where event.type in ("start", "process_started", "info") and
    process.name : "rundll32.exe" and process.args_count == 1] [network
    where process.name : "rundll32.exe" and network.protocol != "dns" and
    network.direction == "outgoing" and not cidrmatch(destination.ip,
    "10.0.0.0/8", "172.16.0.0/12", "192.168.0.0/16", "127.0.0.0/8")]
Version 8 (7.12.0 release)
  • Formatting only
Version 7 (7.11.0 release)
  • Updated query, changed from:

    sequence by process.entity_id [process where process.name :
    "rundll32.exe" and event.type == "start"] [network where
    process.name : "rundll32.exe" and not cidrmatch(destination.ip,
    "10.0.0.0/8", "172.16.0.0/12", "192.168.0.0/16", "127.0.0.0/8")]
Version 6 (7.10.0 release)
  • Updated query, changed from:

    event.category:network and event.type:connection and
    process.name:rundll32.exe and not destination.ip:(10.0.0.0/8 or
    172.16.0.0/12 or 192.168.0.0/16 or 127.0.0.0/8)
Version 5 (7.9.1 release)
  • Formatting only
Version 4 (7.9.0 release)
  • Updated query, changed from:

    process.name:rundll32.exe and event.action:"Network connection
    detected (rule: NetworkConnect)" and not destination.ip:(10.0.0.0/8 or
    172.16.0.0/12 or 192.168.0.0/16 or 127.0.0.0/8)
Version 3 (7.8.0 release)
  • Updated query, changed from:

    process.name:rundll32.exe and event.action:"Network connection
    detected (rule: NetworkConnect)" and not destination.ip:(10.0.0.0/8 or
    172.16.0.0/12 or 192.168.0.0/16)
Version 2 (7.7.0 release)
  • Updated query, changed from:

    process.name:rundll32.exe and event.action:"Network connection
    detected (rule: NetworkConnect)" and not destination.ip:10.0.0.0/8 and
    not destination.ip:172.16.0.0/12 and not destination.ip:192.168.0.0/16
Was this helpful?
Feedback