let lookBack = 14d;
let timeframe = 1d;
let user_agents_list = Cisco_Umbrella
| where EventType == "proxylogs"
| where TimeGenerated > ago(lookBack) and TimeGenerated < ago(timeframe)
| summarize count() by HttpUserAgentOriginal
| summarize make_list(HttpUserAgentOriginal);
Cisco_Umbrella
| where EventType == "proxylogs"
| where TimeGenerated > ago(timeframe)
| where HttpUserAgentOriginal !in (user_agents_list)
| extend Message = "Rare User Agent"
| project Message, SrcIpAddr, DstIpAddr, UrlOriginal, TimeGenerated, HttpUserAgentOriginal
id: 8c8de3fa-6425-4623-9cd9-45de1dd0569a
triggerOperator: gt
OriginalUri: https://github.com/Azure/Azure-Sentinel/blob/master/Detections/CiscoUmbrella/CiscoUmbrellaRareUserAgentDetected.yaml
requiredDataConnectors:
- dataTypes:
- Cisco_Umbrella_proxy_CL
connectorId: CiscoUmbrellaDataConnector
description: |
'Rule helps to detect a rare user-agents indicating web browsing activity by an unusual process other than a web browser.'
severity: Medium
queryPeriod: 14d
kind: Scheduled
tactics:
- CommandAndControl
queryFrequency: 1d
query: |
let lookBack = 14d;
let timeframe = 1d;
let user_agents_list = Cisco_Umbrella
| where EventType == "proxylogs"
| where TimeGenerated > ago(lookBack) and TimeGenerated < ago(timeframe)
| summarize count() by HttpUserAgentOriginal
| summarize make_list(HttpUserAgentOriginal);
Cisco_Umbrella
| where EventType == "proxylogs"
| where TimeGenerated > ago(timeframe)
| where HttpUserAgentOriginal !in (user_agents_list)
| extend Message = "Rare User Agent"
| project Message, SrcIpAddr, DstIpAddr, UrlOriginal, TimeGenerated, HttpUserAgentOriginal
version: 1.1.2
triggerThreshold: 0
entityMappings:
- entityType: URL
fieldMappings:
- columnName: UrlOriginal
identifier: Url
- entityType: IP
fieldMappings:
- columnName: SrcIpAddr
identifier: Address
name: Cisco Umbrella - Rare User Agent Detected
{
"$schema": "https://schema.management.azure.com/schemas/2019-04-01/deploymentTemplate.json#",
"contentVersion": "1.0.0.0",
"parameters": {
"workspace": {
"type": "String"
}
},
"resources": [
{
"apiVersion": "2024-01-01-preview",
"id": "[concat(resourceId('Microsoft.OperationalInsights/workspaces/providers', parameters('workspace'), 'Microsoft.SecurityInsights'),'/alertRules/8c8de3fa-6425-4623-9cd9-45de1dd0569a')]",
"kind": "Scheduled",
"name": "[concat(parameters('workspace'),'/Microsoft.SecurityInsights/8c8de3fa-6425-4623-9cd9-45de1dd0569a')]",
"properties": {
"alertRuleTemplateName": "8c8de3fa-6425-4623-9cd9-45de1dd0569a",
"customDetails": null,
"description": "'Rule helps to detect a rare user-agents indicating web browsing activity by an unusual process other than a web browser.'\n",
"displayName": "Cisco Umbrella - Rare User Agent Detected",
"enabled": true,
"entityMappings": [
{
"entityType": "URL",
"fieldMappings": [
{
"columnName": "UrlOriginal",
"identifier": "Url"
}
]
},
{
"entityType": "IP",
"fieldMappings": [
{
"columnName": "SrcIpAddr",
"identifier": "Address"
}
]
}
],
"OriginalUri": "https://github.com/Azure/Azure-Sentinel/blob/master/Detections/CiscoUmbrella/CiscoUmbrellaRareUserAgentDetected.yaml",
"query": "let lookBack = 14d;\nlet timeframe = 1d;\nlet user_agents_list = Cisco_Umbrella\n| where EventType == \"proxylogs\"\n| where TimeGenerated > ago(lookBack) and TimeGenerated < ago(timeframe)\n| summarize count() by HttpUserAgentOriginal\n| summarize make_list(HttpUserAgentOriginal);\nCisco_Umbrella\n| where EventType == \"proxylogs\"\n| where TimeGenerated > ago(timeframe)\n| where HttpUserAgentOriginal !in (user_agents_list)\n| extend Message = \"Rare User Agent\"\n| project Message, SrcIpAddr, DstIpAddr, UrlOriginal, TimeGenerated, HttpUserAgentOriginal\n",
"queryFrequency": "P1D",
"queryPeriod": "P14D",
"severity": "Medium",
"subTechniques": [],
"suppressionDuration": "PT1H",
"suppressionEnabled": false,
"tactics": [
"CommandAndControl"
],
"templateVersion": "1.1.2",
"triggerOperator": "GreaterThan",
"triggerThreshold": 0
},
"type": "Microsoft.OperationalInsights/workspaces/providers/alertRules"
}
]
}