LOLBAS Network Connection On Uncommon Port
SPLUNK detection rule by Steven Dick, Nasreddine Bencherchali, Splunk · Apache-2.0
The following analytic identifies Living Off the Land Binaries and Scripts (LOLBAS) that can legitimately initiate public network connections but are communicating over uncommon destination ports.
It leverages the Network Traffic data model and applies per-binary common-port exclusions to reduce false positives while preserving suspicious non-standard communication.
This behavior may indicate payload download, command-and-control, proxy execution, or attempts to blend malicious traffic into trusted Windows binaries.
Join this detection with the Process Execution events to provide context and avoid false positives.
name: LOLBAS Network Connection On Uncommon Port
id: a6628e6d-be28-4278-b17d-6b5a32968eea
version: 1
creation_date: '2026-08-24'
modification_date: '2026-08-24'
author: Steven Dick, Nasreddine Bencherchali, Splunk
status: production
type: Anomaly
description: |
The following analytic identifies Living Off the Land Binaries and Scripts (LOLBAS) that can legitimately initiate public network connections but are communicating over uncommon destination ports.
It leverages the Network Traffic data model and applies per-binary common-port exclusions to reduce false positives while preserving suspicious non-standard communication.
This behavior may indicate payload download, command-and-control, proxy execution, or attempts to blend malicious traffic into trusted Windows binaries.
Join this detection with the Process Execution events to provide context and avoid false positives.
data_source:
- Sysmon EventID 3
search: |
| tstats `security_content_summariesonly`
count min(_time) as firstTime
max(_time) as lastTime
from datamodel=Network_Traffic.All_Traffic where
All_Traffic.app IN (
"*\\bitsadmin.exe",
"*\\certutil.exe",
"*\\cmstp.exe",
"*\\cscript.exe",
"*\\ftp.exe",
"*\\hh.exe",
"*\\ie4uinit.exe",
"*\\ieexec.exe",
"*\\msbuild.exe",
"*\\msdt.exe",
"*\\mshta.exe",
"*\\msiexec.exe",
"*\\presentationhost.exe",
"*\\settingsynchost.exe",
"*\\syncappvpublishingserver.exe",
"*\\workfolders.exe",
"*\\wscript.exe",
"*\\wuauclt.exe"
)
NOT All_Traffic.dest_ip IN (
"10.0.0.0/8", "172.16.0.0/12", "192.168.0.0/16",
"100.64.0.0/10", "127.0.0.0/8", "169.254.0.0/16",
"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", "192.88.99.0/24", "224.0.0.0/4",
"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"
)
NOT (
(
All_Traffic.app IN (
"*\\cscript.exe",
"*\\wscript.exe"
)
All_Traffic.dest_port IN ("80", "443", "3128")
)
OR
(
All_Traffic.app="*\\ftp.exe"
All_Traffic.dest_port IN ("20", "21", "989", "990")
)
OR
(
All_Traffic.app IN (
"*\\bitsadmin.exe",
"*\\certutil.exe",
"*\\cmstp.exe",
"*\\hh.exe",
"*\\ieexec.exe",
"*\\msbuild.exe",
"*\\msdt.exe",
"*\\mshta.exe",
"*\\msiexec.exe",
"*\\presentationhost.exe",
"*\\settingsynchost.exe",
"*\\syncappvpublishingserver.exe",
"*\\workfolders.exe",
"*\\wuauclt.exe"
)
All_Traffic.dest_port IN ("80", "443")
)
OR
(
All_Traffic.app IN (
"*\\certutil.exe",
"*\\ie4uinit.exe"
)
All_Traffic.dest_port IN ("389")
)
)
by All_Traffic.action All_Traffic.app All_Traffic.dest
All_Traffic.dest_ip All_Traffic.dest_port
All_Traffic.direction All_Traffic.dvc All_Traffic.protocol
All_Traffic.protocol_version All_Traffic.src
All_Traffic.src_ip All_Traffic.src_port
All_Traffic.transport All_Traffic.user
All_Traffic.vendor_product
| `drop_dm_object_name(All_Traffic)`
| `security_content_ctime(firstTime)`
| `security_content_ctime(lastTime)`
| `lolbas_network_connection_on_uncommon_port_filter`
how_to_implement: |-
To successfully implement this detection you must ingest events into the Network Traffic data model that contain the source, destination, destination port, and communicating process name in the app field.
Sysmon EventID 3 is a common source for this data when normalized into the Network Traffic data model.
known_false_positives: |-
Legitimate software installation, support tooling, scripting, synchronization, or update workflows may still use uncommon ports in some environments.
Tune approved destinations, ports, and process paths with the analytic filter macro.
references:
- https://lolbas-project.github.io/#
- https://www.sans.org/presentations/lolbin-detection-methods-seven-common-attacks-revealed/
drilldown_searches:
- name: View the detection results for - "$src$"
search: '%original_detection_search% | search src = "$src$"'
earliest_offset: $info_min_time$
latest_offset: $info_max_time$
- name: View risk events for the last 7 days for - "$src$"
search: '| from datamodel Risk.All_Risk | search normalized_risk_object IN ("$src$") | stats count min(_time) as firstTime max(_time) as lastTime values(search_name) as "Search Name" values(risk_message) as "Risk Message" values(analyticstories) as "Analytic Stories" values(annotations._all) as "Annotations" values(annotations.mitre_attack.mitre_tactic) as "ATT&CK Tactics" by normalized_risk_object | `security_content_ctime(firstTime)` | `security_content_ctime(lastTime)`'
earliest_offset: 7d
latest_offset: "0"
intermediate_findings:
entities:
- field: dest
type: system
score: 20
message: LOLBAS process [$app$] on [$src$] connected to public destination [$dest_ip$] over uncommon port [$dest_port$].
threat_objects:
- field: app
type: process_name
- field: dest_ip
type: ip_address
analytic_story:
- Fake CAPTCHA Campaigns
- Living Off The Land
- Malicious Inno Setup Loader
- Water Gamayun
- APT37 Rustonotto and FadeStealer
- GhostRedirector IIS Module and Rungan Backdoor
- Hellcat Ransomware
- NetSupport RMM Tool Abuse
asset_type: Endpoint
mitre_attack_id:
- T1105
- T1567
- T1218
product:
- Splunk Enterprise
- Splunk Enterprise Security
- Splunk Cloud
category: endpoint
security_domain: network
tests:
- name: Common Port Suppression Test
attack_data:
- data: https://media.githubusercontent.com/media/splunk/attack_data/master/datasets/attack_techniques/T1218/lolbas_with_network_traffic/lolbas_with_network_traffic.log
source: XmlWinEventLog:Microsoft-Windows-Sysmon/Operational
sourcetype: XmlWinEventLog
expected_results: 0
test_type: unit
CIRCL