OpenCanary - NMAP NULL Scan

Status: experimental
Severity: high
Log source: category application, product opencanary
Author: Marco Pedrinazzi (@pedrinazziM)
Source: github.com/SigmaHQ/sigma

Detects instances where an OpenCanary node has been targeted by a NMAP NULL Scan

Known false positives

Unlikely

MITRE ATT&CK coverage

Tactic	Techniques
Discovery	`T1046` Network Service Discovery

Rule body

title: OpenCanary - NMAP NULL Scan
id: 68b8547b-107f-43f3-97fb-900a7d63c190
status: experimental
description: Detects instances where an OpenCanary node has been targeted by a NMAP NULL Scan
references:
    - https://opencanary.readthedocs.io/en/latest/starting/configuration.html#services-configuration
    - https://github.com/thinkst/opencanary/blob/a0896adfcaf0328cfd5829fe10d2878c7445138e/opencanary/logger.py#L52
author: Marco Pedrinazzi (@pedrinazziM)
date: 2026-01-06
tags:
    - attack.discovery
    - attack.t1046
logsource:
    category: application
    product: opencanary
detection:
    selection:
        logtype: 5003
    condition: selection
falsepositives:
    - Unlikely
level: high

Stages and Predicates

Stage 0: `condition`

selection

Stage 1: `selection`

selection:
    logtype: 5003

Indicators

These rows show field, operator, and value matches.

Field	Kind	Values	Search
`logtype`	eq	`5003`	`field:"logtype" kind:eq value:"5003"`

OpenCanary - NMAP NULL Scan

Known false positives

MITRE ATT&CK coverage

Rule body

Stages and Predicates

Stage 0: condition

Stage 1: selection

Indicators

Stage 0: `condition`

Stage 1: `selection`