GitLab - Abnormal number of repositories deleted

let LearningPeriod = 7d;
let BinTime = 1h;
let RunTime = 1h;
let StartTime = 1h;
let NumberOfStds = 3;
let MinThreshold = 10.0;
let EndRunTime = StartTime - RunTime;
let EndLearningTime = StartTime + LearningPeriod;
let GitLabRepositoryDestroyEvents = (GitLabAudit
| where RemoveAction == "project" or RemoveAction == "repository");
GitLabRepositoryDestroyEvents
| where TimeGenerated between (ago(EndLearningTime) .. ago(StartTime))
| summarize count() by bin(TimeGenerated, BinTime)
| summarize AvgInLearning = avg(count_), StdInLearning = stdev(count_)
| extend LearningThreshold = max_of(AvgInLearning + StdInLearning * NumberOfStds, MinThreshold)
| extend Dummy = 1
| join kind=innerunique (GitLabRepositoryDestroyEvents
| where TimeGenerated between (ago(StartTime) .. ago(EndRunTime))
| summarize CountInRunTime = count() by bin(TimeGenerated, BinTime)
| extend Dummy = 1) on Dummy
| project-away Dummy
| where CountInRunTime > LearningThreshold

id: 3efd09bd-a582-4410-b7ec-5ff21cfad7bd
tactics:
- Impact
queryPeriod: 1d
triggerThreshold: 0
name: GitLab - Abnormal number of repositories deleted
query: |
  let LearningPeriod = 7d;
  let BinTime = 1h;
  let RunTime = 1h;
  let StartTime = 1h;
  let NumberOfStds = 3;
  let MinThreshold = 10.0;
  let EndRunTime = StartTime - RunTime;
  let EndLearningTime = StartTime + LearningPeriod;
  let GitLabRepositoryDestroyEvents = (GitLabAudit
  | where RemoveAction == "project" or RemoveAction == "repository");
  GitLabRepositoryDestroyEvents
  | where TimeGenerated between (ago(EndLearningTime) .. ago(StartTime))
  | summarize count() by bin(TimeGenerated, BinTime)
  | summarize AvgInLearning = avg(count_), StdInLearning = stdev(count_)
  | extend LearningThreshold = max_of(AvgInLearning + StdInLearning * NumberOfStds, MinThreshold)
  | extend Dummy = 1
  | join kind=innerunique (GitLabRepositoryDestroyEvents
  | where TimeGenerated between (ago(StartTime) .. ago(EndRunTime))
  | summarize CountInRunTime = count() by bin(TimeGenerated, BinTime)
  | extend Dummy = 1) on Dummy
  | project-away Dummy
  | where CountInRunTime > LearningThreshold  
severity: Medium
triggerOperator: gt
kind: Scheduled
relevantTechniques:
- T1485
OriginalUri: https://github.com/Azure/Azure-Sentinel/blob/master/Solutions/GitLab/Analytic Rules/GitLab_Repo_Deletion.yaml
queryFrequency: 1h
requiredDataConnectors:
- connectorId: SyslogAma
  dataTypes:
  - Syslog
description: |
    'This hunting queries identify an unusual increase of repo deletion activities adversaries may want to disrupt availability or compromise integrity by deleting business data.'
status: Available
version: 1.0.1
entityMappings:
- fieldMappings:
  - columnName: IPAddress
    identifier: Address
  entityType: IP
- fieldMappings:
  - columnName: AuthorName
    identifier: FullName
  entityType: Account

{
  "$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/3efd09bd-a582-4410-b7ec-5ff21cfad7bd')]",
      "kind": "Scheduled",
      "name": "[concat(parameters('workspace'),'/Microsoft.SecurityInsights/3efd09bd-a582-4410-b7ec-5ff21cfad7bd')]",
      "properties": {
        "alertRuleTemplateName": "3efd09bd-a582-4410-b7ec-5ff21cfad7bd",
        "customDetails": null,
        "description": "'This hunting queries identify an unusual increase of repo deletion activities adversaries may want to disrupt availability or compromise integrity by deleting business data.'\n",
        "displayName": "GitLab - Abnormal number of repositories deleted",
        "enabled": true,
        "entityMappings": [
          {
            "entityType": "IP",
            "fieldMappings": [
              {
                "columnName": "IPAddress",
                "identifier": "Address"
              }
            ]
          },
          {
            "entityType": "Account",
            "fieldMappings": [
              {
                "columnName": "AuthorName",
                "identifier": "FullName"
              }
            ]
          }
        ],
        "OriginalUri": "https://github.com/Azure/Azure-Sentinel/blob/master/Solutions/GitLab/Analytic Rules/GitLab_Repo_Deletion.yaml",
        "query": "let LearningPeriod = 7d;\nlet BinTime = 1h;\nlet RunTime = 1h;\nlet StartTime = 1h;\nlet NumberOfStds = 3;\nlet MinThreshold = 10.0;\nlet EndRunTime = StartTime - RunTime;\nlet EndLearningTime = StartTime + LearningPeriod;\nlet GitLabRepositoryDestroyEvents = (GitLabAudit\n| where RemoveAction == \"project\" or RemoveAction == \"repository\");\nGitLabRepositoryDestroyEvents\n| where TimeGenerated between (ago(EndLearningTime) .. ago(StartTime))\n| summarize count() by bin(TimeGenerated, BinTime)\n| summarize AvgInLearning = avg(count_), StdInLearning = stdev(count_)\n| extend LearningThreshold = max_of(AvgInLearning + StdInLearning * NumberOfStds, MinThreshold)\n| extend Dummy = 1\n| join kind=innerunique (GitLabRepositoryDestroyEvents\n| where TimeGenerated between (ago(StartTime) .. ago(EndRunTime))\n| summarize CountInRunTime = count() by bin(TimeGenerated, BinTime)\n| extend Dummy = 1) on Dummy\n| project-away Dummy\n| where CountInRunTime > LearningThreshold\n",
        "queryFrequency": "PT1H",
        "queryPeriod": "P1D",
        "severity": "Medium",
        "status": "Available",
        "subTechniques": [],
        "suppressionDuration": "PT1H",
        "suppressionEnabled": false,
        "tactics": [
          "Impact"
        ],
        "techniques": [
          "T1485"
        ],
        "templateVersion": "1.0.1",
        "triggerOperator": "GreaterThan",
        "triggerThreshold": 0
      },
      "type": "Microsoft.OperationalInsights/workspaces/providers/alertRules"
    }
  ]
}