Detection rules › Splunk
masscan Execution - Windows (PowerShell)
Masscan is a high-performance, open-source network scanning tool designed to scan large ranges of IP addresses for open ports, offering similar functionality to Nmap but with significantly faster scanning capabilities. Threat actors may use port and vulnerability scanning tools to identify running services and potential exploits on remote hosts and network devices. This use case detects masscan executions.
MITRE ATT&CK coverage
| Tactic | Techniques |
|---|---|
| Discovery | T1046 Network Service Discovery |
References
Event coverage
| Provider | Event | Title |
|---|---|---|
| PowerShell | Event ID 4103 | Payload Context: ContextInfo User Data: UserData. |
| PowerShell | Event ID 4104 | Creating Scriptblock text (MessageNumber of MessageTotal). |
Rule body yaml
id: '36445.64013'
title: masscan Execution - Windows
description: Masscan is a high-performance, open-source network scanning tool designed
to scan large ranges of IP addresses for open ports, offering similar functionality
to Nmap but with significantly faster scanning capabilities. Threat actors may use
port and vulnerability scanning tools to identify running services and potential
exploits on remote hosts and network devices. This use case detects masscan executions.
logic_format: Splunk
logic: '`get_endpoint_data` `get_endpoint_data_powershell` (TERM(EventCode=4103) OR
"<EventID>4103<" OR TERM(EventCode=4104) OR "<EventID>4104<") (TERM(masscan) OR
"masscan.exe") | table _time, host, user, process | bin span=1s | stats values(*)
as * by _time, host '
techniques:
- discovery:network service discovery
technique_id:
- T1046
data_category:
- PowerShell logs
references:
- https://github.com/robertdavidgraham/masscan/tree/master
- https://attack.mitre.org/techniques/T1046/
- https://cybersecurity.att.com/blogs/labs-research/teamtnt-with-new-campaign-aka-chimaera
- https://unit42.paloaltonetworks.com/hildegard-malware-teamtnt/
- https://www.kali.org/tools/masscan/
Stages and Predicates
Stage 1: search
`get_endpoint_data` `get_endpoint_data_powershell` (TERM(EventCode=4103) OR "<EventID>4103<" OR TERM(EventCode=4104) OR "<EventID>4104<") (TERM(masscan) OR "masscan.exe")
Stage 2: table
| table _time, host, user, process
Stage 3: bucket
| bin span=1s
Stage 4: stats
| stats values(*) as * by _time, host
Indicators
Each row is a field, operator, and value that the rule matches. The corpus column counts how many other rules in the catalog look for the same combination: high numbers point to widely-used, community-vetted indicators. Blank or 1 shows that the indicator is specific to this rule.
| Field | Kind | Values |
|---|---|---|
EventCode | eq |
|
Search terms
Bare-string tokens in the SPL search body. Splunk matches each token against _raw (the untyped raw event text) anywhere it appears, not against a specific field. These don't surface in the Indicators table because they aren't predicates on a known field.
| Stage | Term |
|---|---|
| 1 | TERM |
| 1 | "<EventID>4103<" |
| 1 | TERM |
| 1 | "<EventID>4104<" |
| 1 | TERM |
| 1 | masscan |
| 1 | "masscan.exe" |