OCI - Unexpected user agent

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

'Detects unexpected user agent strings.'

MITRE ATT&CK coverage

Tactic	Techniques
Initial Access	`T1190` Exploit Public-Facing Application

Rule body

id: a0b9a7ca-3e6d-4996-ae35-759df1d67a54
name: OCI - Unexpected user agent
description: |
  'Detects unexpected user agent strings.'
severity: Medium
status: Available
requiredDataConnectors:
  - connectorId: OracleCloudInfrastructureLogsConnector
    dataTypes:
      - OCILogs
  - connectorId: OracleCloudInfraConnector
    dataTypes:
      - OCI_LogsV2_CL
queryFrequency: 1h
queryPeriod: 1h
triggerOperator: gt
triggerThreshold: 0
tactics:
  - InitialAccess
relevantTechniques:
  - T1190
query: |
  OCILogs
  | where isnotempty(HttpUserAgentOriginal)
  | where strlen(HttpUserAgentOriginal) <= 10
  | extend IPCustomEntity = SrcIpAddr
entityMappings:
  - entityType: IP
    fieldMappings:
      - identifier: Address
        columnName: IPCustomEntity
version: 1.0.1
kind: Scheduled

Stages and Predicates

Stage 1: `source`

OCILogs

Stage 2: `where`

| where isnotempty(HttpUserAgentOriginal)

Stage 3: `where`

| where strlen(HttpUserAgentOriginal) <= 10

Stage 4: `extend`

| extend IPCustomEntity = SrcIpAddr

Indicators

These rows show field, operator, and value matches.

Field	Kind	Values	Search
`HttpUserAgentOriginal`	is_not_null	(no value, null check)	`field:"HttpUserAgentOriginal" kind:is_not_null`
`HttpUserAgentOriginal`	le	`10` transforms: `strlen`	`field:"HttpUserAgentOriginal" kind:le value:"10"`

Output fields

These fields are emitted when the rule matches.

Field	Source
`IPCustomEntity`	`extend`

OCI - Unexpected user agent

MITRE ATT&CK coverage

Rule body

Stages and Predicates

Stage 1: source

Stage 2: where

Stage 3: where

Stage 4: extend

Indicators

Output fields

Stage 1: `source`

Stage 2: `where`

Stage 3: `where`

Stage 4: `extend`