Excessive Amount of Denied Connections from a Single Source

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Id	3d645a88-2724-41a7-adea-db74c439cf79
Rulename	Excessive Amount of Denied Connections from a Single Source
Description	This creates an incident in the event that a single source IP address generates a excessive amount of denied connections.
Severity	Medium
Tactics	Impact
Techniques	T1499
Required data connectors	SophosXGFirewall SyslogAma
Kind	Scheduled
Query frequency	1h
Query period	1h
Trigger threshold	0
Trigger operator	gt
Source Uri	https://github.com/Azure/Azure-Sentinel/blob/master/Solutions/Sophos XG Firewall/Analytic Rules/ExcessiveAmountofDeniedConnectionsfromASingleSource.yaml
Version	1.0.3
Arm template	3d645a88-2724-41a7-adea-db74c439cf79.json

KQL

let threshold = 5000;
SophosXGFirewall
| where Log_Type =~ "Firewall" and Status =~ "Deny"
| summarize count() by Src_IP, bin(TimeGenerated,5m)
| where count_ > threshold

YAML

relevantTechniques:
- T1499
name: Excessive Amount of Denied Connections from a Single Source
requiredDataConnectors:
- dataTypes:
  - Syslog
  connectorId: SophosXGFirewall
- datatypes:
  - Syslog
  connectorId: SyslogAma
entityMappings:
- fieldMappings:
  - identifier: Address
    columnName: Src_IP
  entityType: IP
triggerThreshold: 0
id: 3d645a88-2724-41a7-adea-db74c439cf79
tactics:
- Impact
version: 1.0.3
OriginalUri: https://github.com/Azure/Azure-Sentinel/blob/master/Solutions/Sophos XG Firewall/Analytic Rules/ExcessiveAmountofDeniedConnectionsfromASingleSource.yaml
queryPeriod: 1h
kind: Scheduled
queryFrequency: 1h
severity: Medium
status: Available
description: |
    'This creates an incident in the event that a single source IP address generates a excessive amount of denied connections.'
query: |
  let threshold = 5000;
  SophosXGFirewall
  | where Log_Type =~ "Firewall" and Status =~ "Deny"
  | summarize count() by Src_IP, bin(TimeGenerated,5m)
  | where count_ > threshold  
triggerOperator: gt

ARM

{
  "$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/3d645a88-2724-41a7-adea-db74c439cf79')]",
      "kind": "Scheduled",
      "name": "[concat(parameters('workspace'),'/Microsoft.SecurityInsights/3d645a88-2724-41a7-adea-db74c439cf79')]",
      "properties": {
        "alertRuleTemplateName": "3d645a88-2724-41a7-adea-db74c439cf79",
        "customDetails": null,
        "description": "'This creates an incident in the event that a single source IP address generates a excessive amount of denied connections.'\n",
        "displayName": "Excessive Amount of Denied Connections from a Single Source",
        "enabled": true,
        "entityMappings": [
          {
            "entityType": "IP",
            "fieldMappings": [
              {
                "columnName": "Src_IP",
                "identifier": "Address"
              }
            ]
          }
        ],
        "OriginalUri": "https://github.com/Azure/Azure-Sentinel/blob/master/Solutions/Sophos XG Firewall/Analytic Rules/ExcessiveAmountofDeniedConnectionsfromASingleSource.yaml",
        "query": "let threshold = 5000;\nSophosXGFirewall\n| where Log_Type =~ \"Firewall\" and Status =~ \"Deny\"\n| summarize count() by Src_IP, bin(TimeGenerated,5m)\n| where count_ > threshold\n",
        "queryFrequency": "PT1H",
        "queryPeriod": "PT1H",
        "severity": "Medium",
        "status": "Available",
        "subTechniques": [],
        "suppressionDuration": "PT1H",
        "suppressionEnabled": false,
        "tactics": [
          "Impact"
        ],
        "techniques": [
          "T1499"
        ],
        "templateVersion": "1.0.3",
        "triggerOperator": "GreaterThan",
        "triggerThreshold": 0
      },
      "type": "Microsoft.OperationalInsights/workspaces/providers/alertRules"
    }
  ]
}