Anomaly in SMB TrafficASIM Network Session schema

// Define the threshold for deviation
let threshold = 50;
// Define the time range for the baseline data
let starttime = 14d;
let endtime = 1d;
// Define the SMB ports to monitor
let SMBPorts = dynamic(["139", "445"]);
// Get the baseline data for user network sessions and Filter for the defined time range
let userBaseline = _Im_NetworkSession(starttime=ago(starttime), endtime=ago(endtime))
  | where ipv4_is_private(SrcIpAddr) and tostring(DstPortNumber) has_any (SMBPorts) and SrcIpAddr != DstIpAddr // Filter for private IP addresses and SMB ports
  | summarize Count = count() by SrcIpAddr, DstPortNumber // Group by source IP and destination port
  | summarize AvgCount = avg(Count) by SrcIpAddr, DstPortNumber; // Calculate the average count
// Get the recent user activity data and Filter for recent activity
let recentUserActivity = _Im_NetworkSession(starttime=ago(endtime))
  | where ipv4_is_private(SrcIpAddr) and tostring(DstPortNumber) has_any (SMBPorts) and SrcIpAddr != DstIpAddr // Filter for private IP addresses and SMB ports
  | summarize StartTimeUtc = min(TimeGenerated), EndTimeUtc = max(TimeGenerated), RecentCount = count() by SrcIpAddr, DstPortNumber; // Group by source IP and destination port
// Join the baseline and recent activity data
let UserBehaviorAnalysis = userBaseline
  | join kind=inner (recentUserActivity) on SrcIpAddr, DstPortNumber
  | extend Deviation = abs(RecentCount - AvgCount) / AvgCount; // Calculate the deviation
// Filter for deviations greater than the threshold
UserBehaviorAnalysis
  | where Deviation > threshold
  | project SrcIpAddr, DstPortNumber, Deviation, Count = RecentCount; // Project the required columns

relevantTechniques:
- T1021
- T1021.002
name: Anomaly in SMB Traffic(ASIM Network Session schema)
requiredDataConnectors: []
entityMappings:
- fieldMappings:
  - identifier: Address
    columnName: SrcIpAddr
  entityType: IP
triggerThreshold: 0
id: 8717e498-7b5d-4e23-9e7c-fa4913dbfd79
tactics:
- LateralMovement
version: 1.0.0
queryPeriod: 14d
OriginalUri: https://github.com/Azure/Azure-Sentinel/blob/master/Solutions/Network Session Essentials/Analytic Rules/Anomaly in SMB Traffic(ASIM Network Session schema).yaml
triggerOperator: gt
kind: Scheduled
tags:
- Schema: ASimNetworkSessions
  SchemaVersion: 0.2.4
eventGroupingSettings:
  aggregationKind: AlertPerResult
queryFrequency: 1d
severity: Medium
status: Available
description: |
    'This detection detects abnormal SMB traffic, a file-sharing protocol. By calculating the average deviation of SMB connections over last 14 days, flagging sources exceeding 50 average deviations.'
query: |
  // Define the threshold for deviation
  let threshold = 50;
  // Define the time range for the baseline data
  let starttime = 14d;
  let endtime = 1d;
  // Define the SMB ports to monitor
  let SMBPorts = dynamic(["139", "445"]);
  // Get the baseline data for user network sessions and Filter for the defined time range
  let userBaseline = _Im_NetworkSession(starttime=ago(starttime), endtime=ago(endtime))
    | where ipv4_is_private(SrcIpAddr) and tostring(DstPortNumber) has_any (SMBPorts) and SrcIpAddr != DstIpAddr // Filter for private IP addresses and SMB ports
    | summarize Count = count() by SrcIpAddr, DstPortNumber // Group by source IP and destination port
    | summarize AvgCount = avg(Count) by SrcIpAddr, DstPortNumber; // Calculate the average count
  // Get the recent user activity data and Filter for recent activity
  let recentUserActivity = _Im_NetworkSession(starttime=ago(endtime))
    | where ipv4_is_private(SrcIpAddr) and tostring(DstPortNumber) has_any (SMBPorts) and SrcIpAddr != DstIpAddr // Filter for private IP addresses and SMB ports
    | summarize StartTimeUtc = min(TimeGenerated), EndTimeUtc = max(TimeGenerated), RecentCount = count() by SrcIpAddr, DstPortNumber; // Group by source IP and destination port
  // Join the baseline and recent activity data
  let UserBehaviorAnalysis = userBaseline
    | join kind=inner (recentUserActivity) on SrcIpAddr, DstPortNumber
    | extend Deviation = abs(RecentCount - AvgCount) / AvgCount; // Calculate the deviation
  // Filter for deviations greater than the threshold
  UserBehaviorAnalysis
    | where Deviation > threshold
    | project SrcIpAddr, DstPortNumber, Deviation, Count = RecentCount; // Project the required columns  

{
  "$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/8717e498-7b5d-4e23-9e7c-fa4913dbfd79')]",
      "kind": "Scheduled",
      "name": "[concat(parameters('workspace'),'/Microsoft.SecurityInsights/8717e498-7b5d-4e23-9e7c-fa4913dbfd79')]",
      "properties": {
        "alertRuleTemplateName": "8717e498-7b5d-4e23-9e7c-fa4913dbfd79",
        "customDetails": null,
        "description": "'This detection detects abnormal SMB traffic, a file-sharing protocol. By calculating the average deviation of SMB connections over last 14 days, flagging sources exceeding 50 average deviations.'\n",
        "displayName": "Anomaly in SMB Traffic(ASIM Network Session schema)",
        "enabled": true,
        "entityMappings": [
          {
            "entityType": "IP",
            "fieldMappings": [
              {
                "columnName": "SrcIpAddr",
                "identifier": "Address"
              }
            ]
          }
        ],
        "eventGroupingSettings": {
          "aggregationKind": "AlertPerResult"
        },
        "OriginalUri": "https://github.com/Azure/Azure-Sentinel/blob/master/Solutions/Network Session Essentials/Analytic Rules/Anomaly in SMB Traffic(ASIM Network Session schema).yaml",
        "query": "// Define the threshold for deviation\nlet threshold = 50;\n// Define the time range for the baseline data\nlet starttime = 14d;\nlet endtime = 1d;\n// Define the SMB ports to monitor\nlet SMBPorts = dynamic([\"139\", \"445\"]);\n// Get the baseline data for user network sessions and Filter for the defined time range\nlet userBaseline = _Im_NetworkSession(starttime=ago(starttime), endtime=ago(endtime))\n  | where ipv4_is_private(SrcIpAddr) and tostring(DstPortNumber) has_any (SMBPorts) and SrcIpAddr != DstIpAddr // Filter for private IP addresses and SMB ports\n  | summarize Count = count() by SrcIpAddr, DstPortNumber // Group by source IP and destination port\n  | summarize AvgCount = avg(Count) by SrcIpAddr, DstPortNumber; // Calculate the average count\n// Get the recent user activity data and Filter for recent activity\nlet recentUserActivity = _Im_NetworkSession(starttime=ago(endtime))\n  | where ipv4_is_private(SrcIpAddr) and tostring(DstPortNumber) has_any (SMBPorts) and SrcIpAddr != DstIpAddr // Filter for private IP addresses and SMB ports\n  | summarize StartTimeUtc = min(TimeGenerated), EndTimeUtc = max(TimeGenerated), RecentCount = count() by SrcIpAddr, DstPortNumber; // Group by source IP and destination port\n// Join the baseline and recent activity data\nlet UserBehaviorAnalysis = userBaseline\n  | join kind=inner (recentUserActivity) on SrcIpAddr, DstPortNumber\n  | extend Deviation = abs(RecentCount - AvgCount) / AvgCount; // Calculate the deviation\n// Filter for deviations greater than the threshold\nUserBehaviorAnalysis\n  | where Deviation > threshold\n  | project SrcIpAddr, DstPortNumber, Deviation, Count = RecentCount; // Project the required columns\n",
        "queryFrequency": "P1D",
        "queryPeriod": "P14D",
        "severity": "Medium",
        "status": "Available",
        "subTechniques": [
          "T1021.002"
        ],
        "suppressionDuration": "PT1H",
        "suppressionEnabled": false,
        "tactics": [
          "LateralMovement"
        ],
        "tags": [
          {
            "Schema": "ASimNetworkSessions",
            "SchemaVersion": "0.2.4"
          }
        ],
        "techniques": [
          "T1021"
        ],
        "templateVersion": "1.0.0",
        "triggerOperator": "GreaterThan",
        "triggerThreshold": 0
      },
      "type": "Microsoft.OperationalInsights/workspaces/providers/alertRules"
    }
  ]
}