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Azure DevOps Build Variable Modified by New User

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Id3b9a44d7-c651-45ed-816c-eae583a6f2f1
RulenameAzure DevOps Build Variable Modified by New User
DescriptionVariables can be configured and used at any stage of the build process in Azure DevOps to inject values. An attacker with the required permissions could modify

or add to these variables to conduct malicious activity such as changing paths or remote endpoints called during the build. As variables are often changed by users,

just detecting these changes would have a high false positive rate. This detection looks for modifications to variable groups where that user has not been observed

modifying them before.
SeverityMedium
TacticsDefenseEvasion
TechniquesT1578
KindScheduled
Query frequency1d
Query period14d
Trigger threshold0
Trigger operatorgt
Source Urihttps://github.com/Azure/Azure-Sentinel/blob/master/Solutions/AzureDevOpsAuditing/Analytic Rules/ADOVariableModifiedByNewUser.yaml
Version1.0.3
Arm template3b9a44d7-c651-45ed-816c-eae583a6f2f1.json
Deploy To Azure
let lookback = 14d;
let timeframe = 1d;
let historical_data =
AzureDevOpsAuditing
| where TimeGenerated > ago(lookback) and TimeGenerated < ago(timeframe)
| where OperationName =~ "Library.VariableGroupModified"
| extend variables = Data.Variables
| extend VariableGroupId = tostring(Data.VariableGroupId)
| extend UserKey = strcat(VariableGroupId, "-", ActorUserId)
| project UserKey;
AzureDevOpsAuditing
| where TimeGenerated > ago(timeframe)
| where OperationName =~ "Library.VariableGroupModified"
| extend VariableGroupName = tostring(Data.VariableGroupName)
| extend VariableGroupId = tostring(Data.VariableGroupId)
| extend UserKey = strcat(VariableGroupId, "-", ActorUserId)
| where UserKey !in (historical_data)
| project-away UserKey
| project-reorder TimeGenerated, VariableGroupName, ActorUPN, IpAddress, UserAgent
| extend timestamp = TimeGenerated
| extend AccountName = tostring(split(ActorUPN, "@")[0]), AccountUPNSuffix = tostring(split(ActorUPN, "@")[1])
name: Azure DevOps Build Variable Modified by New User
triggerOperator: gt
status: Available
relevantTechniques:
- T1578
query: |
  let lookback = 14d;
  let timeframe = 1d;
  let historical_data =
  AzureDevOpsAuditing
  | where TimeGenerated > ago(lookback) and TimeGenerated < ago(timeframe)
  | where OperationName =~ "Library.VariableGroupModified"
  | extend variables = Data.Variables
  | extend VariableGroupId = tostring(Data.VariableGroupId)
  | extend UserKey = strcat(VariableGroupId, "-", ActorUserId)
  | project UserKey;
  AzureDevOpsAuditing
  | where TimeGenerated > ago(timeframe)
  | where OperationName =~ "Library.VariableGroupModified"
  | extend VariableGroupName = tostring(Data.VariableGroupName)
  | extend VariableGroupId = tostring(Data.VariableGroupId)
  | extend UserKey = strcat(VariableGroupId, "-", ActorUserId)
  | where UserKey !in (historical_data)
  | project-away UserKey
  | project-reorder TimeGenerated, VariableGroupName, ActorUPN, IpAddress, UserAgent
  | extend timestamp = TimeGenerated
  | extend AccountName = tostring(split(ActorUPN, "@")[0]), AccountUPNSuffix = tostring(split(ActorUPN, "@")[1])  
OriginalUri: https://github.com/Azure/Azure-Sentinel/blob/master/Solutions/AzureDevOpsAuditing/Analytic Rules/ADOVariableModifiedByNewUser.yaml
description: |
  'Variables can be configured and used at any stage of the build process in Azure DevOps to inject values. An attacker with the required permissions could modify 
  or add to these variables to conduct malicious activity such as changing paths or remote endpoints called during the build. As variables are often changed by users, 
  just detecting these changes would have a high false positive rate. This detection looks for modifications to variable groups where that user has not been observed 
  modifying them before.'  
triggerThreshold: 0
id: 3b9a44d7-c651-45ed-816c-eae583a6f2f1
kind: Scheduled
severity: Medium
version: 1.0.3
entityMappings:
- fieldMappings:
  - identifier: Name
    columnName: AccountName
  - identifier: UPNSuffix
    columnName: AccountUPNSuffix
  entityType: Account
- fieldMappings:
  - identifier: Address
    columnName: IpAddress
  entityType: IP
queryFrequency: 1d
queryPeriod: 14d
requiredDataConnectors: []
tactics:
- DefenseEvasion
{
  "$schema": "https://schema.management.azure.com/schemas/2019-04-01/deploymentTemplate.json#",
  "contentVersion": "1.0.0.0",
  "parameters": {
    "workspace": {
      "type": "String"
    }
  },
  "resources": [
    {
      "apiVersion": "2023-02-01-preview",
      "id": "[concat(resourceId('Microsoft.OperationalInsights/workspaces/providers', parameters('workspace'), 'Microsoft.SecurityInsights'),'/alertRules/3b9a44d7-c651-45ed-816c-eae583a6f2f1')]",
      "kind": "Scheduled",
      "name": "[concat(parameters('workspace'),'/Microsoft.SecurityInsights/3b9a44d7-c651-45ed-816c-eae583a6f2f1')]",
      "properties": {
        "alertRuleTemplateName": "3b9a44d7-c651-45ed-816c-eae583a6f2f1",
        "customDetails": null,
        "description": "'Variables can be configured and used at any stage of the build process in Azure DevOps to inject values. An attacker with the required permissions could modify \nor add to these variables to conduct malicious activity such as changing paths or remote endpoints called during the build. As variables are often changed by users, \njust detecting these changes would have a high false positive rate. This detection looks for modifications to variable groups where that user has not been observed \nmodifying them before.'\n",
        "displayName": "Azure DevOps Build Variable Modified by New User",
        "enabled": true,
        "entityMappings": [
          {
            "entityType": "Account",
            "fieldMappings": [
              {
                "columnName": "AccountName",
                "identifier": "Name"
              },
              {
                "columnName": "AccountUPNSuffix",
                "identifier": "UPNSuffix"
              }
            ]
          },
          {
            "entityType": "IP",
            "fieldMappings": [
              {
                "columnName": "IpAddress",
                "identifier": "Address"
              }
            ]
          }
        ],
        "OriginalUri": "https://github.com/Azure/Azure-Sentinel/blob/master/Solutions/AzureDevOpsAuditing/Analytic Rules/ADOVariableModifiedByNewUser.yaml",
        "query": "let lookback = 14d;\nlet timeframe = 1d;\nlet historical_data =\nAzureDevOpsAuditing\n| where TimeGenerated > ago(lookback) and TimeGenerated < ago(timeframe)\n| where OperationName =~ \"Library.VariableGroupModified\"\n| extend variables = Data.Variables\n| extend VariableGroupId = tostring(Data.VariableGroupId)\n| extend UserKey = strcat(VariableGroupId, \"-\", ActorUserId)\n| project UserKey;\nAzureDevOpsAuditing\n| where TimeGenerated > ago(timeframe)\n| where OperationName =~ \"Library.VariableGroupModified\"\n| extend VariableGroupName = tostring(Data.VariableGroupName)\n| extend VariableGroupId = tostring(Data.VariableGroupId)\n| extend UserKey = strcat(VariableGroupId, \"-\", ActorUserId)\n| where UserKey !in (historical_data)\n| project-away UserKey\n| project-reorder TimeGenerated, VariableGroupName, ActorUPN, IpAddress, UserAgent\n| extend timestamp = TimeGenerated\n| extend AccountName = tostring(split(ActorUPN, \"@\")[0]), AccountUPNSuffix = tostring(split(ActorUPN, \"@\")[1])\n",
        "queryFrequency": "P1D",
        "queryPeriod": "P14D",
        "severity": "Medium",
        "status": "Available",
        "suppressionDuration": "PT1H",
        "suppressionEnabled": false,
        "tactics": [
          "DefenseEvasion"
        ],
        "techniques": [
          "T1578"
        ],
        "templateVersion": "1.0.3",
        "triggerOperator": "GreaterThan",
        "triggerThreshold": 0
      },
      "type": "Microsoft.OperationalInsights/workspaces/providers/alertRules"
    }
  ]
}