Detection rules › Kusto
Cisco Umbrella - Empty User Agent Detected
'Rule helps to detect empty and unusual user agent indicating web browsing activity by an unusual process other than a web browser.'
MITRE ATT&CK coverage
| Tactic | Techniques |
|---|---|
| Command & Control | No specific technique |
Rule body
id: 2b328487-162d-4034-b472-59f1d53684a1
name: Cisco Umbrella - Empty User Agent Detected
description: |
'Rule helps to detect empty and unusual user agent indicating web browsing activity by an unusual process other than a web browser.'
severity: Medium
requiredDataConnectors:
- connectorId: CiscoUmbrellaDataConnector
dataTypes:
- Cisco_Umbrella_proxy_CL
queryFrequency: 15m
queryPeriod: 15m
triggerOperator: gt
triggerThreshold: 0
tactics:
- CommandAndControl
query: |
let timeframe = 15m;
Cisco_Umbrella
| where EventType == "proxylogs"
| where TimeGenerated > ago(timeframe)
| where HttpUserAgentOriginal == ''
| extend Message = "Empty User Agent"
| project Message, SrcIpAddr, DstIpAddr, UrlOriginal, TimeGenerated
entityMappings:
- entityType: URL
fieldMappings:
- identifier: Url
columnName: UrlOriginal
- entityType: IP
fieldMappings:
- identifier: Address
columnName: SrcIpAddr
version: 1.1.2
kind: Scheduled
Stages and Predicates
Stage 0: let
let timeframe = 15m;
Stage 1: source
Cisco_Umbrella
Stage 2: where
| where EventType == "proxylogs"
Stage 3: where
| where TimeGenerated > ago(timeframe)
Stage 4: where
| where HttpUserAgentOriginal == ''
Stage 5: extend
| extend Message = "Empty User Agent"
Stage 6: project
| project Message, SrcIpAddr, DstIpAddr, UrlOriginal, TimeGenerated
Indicators
These rows show field, operator, and value matches.
| Field | Kind | Values | Search |
|---|---|---|---|
EventType | eq |
| field:"EventType" kind:eq value:"proxylogs" |
Output fields
These fields are emitted when the rule matches.
| Field | Source |
|---|---|
DstIpAddr | project |
Message | project |
SrcIpAddr | project |
TimeGenerated | project |
UrlOriginal | project |