Detection rules › Kusto

Cloudflare - Empty user agent

Status
available
Severity
medium
Time window
1h
Source
github.com/Azure/Azure-Sentinel

'Detects requests where user agent is empty.'

MITRE ATT&CK coverage

Rule body kusto

id: 729c6d21-fad9-4a6a-9c7f-482393c95958
name: Cloudflare - Empty user agent
description: |
  'Detects requests where user agent is empty.'
severity: Medium
status: Available
requiredDataConnectors:
  - connectorId: CloudflareDataConnector
    dataTypes:
      - Cloudflare
queryFrequency: 1h
queryPeriod: 1h
triggerOperator: gt
triggerThreshold: 0
tactics:
  - InitialAccess
relevantTechniques:
  - T1190
  - T1133
query: |
  Cloudflare
  | where isempty(HttpUserAgentOriginal)
entityMappings:
  - entityType: IP
    fieldMappings:
      - identifier: Address
        columnName: SrcIpAddr
version: 1.0.1
kind: Scheduled

Stages and Predicates

Stage 1: source

Cloudflare

Stage 2: where

| where isempty(HttpUserAgentOriginal)

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.

FieldKindValues
HttpUserAgentOriginalis_null
  • (no value, null check)