AWSCloudTrail - Successful brute force attack on S3 Bucket

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Id	31b9e94b-0df6-4a3d-a297-3457b53c5d86
Rulename	AWSCloudTrail - Successful brute force attack on S3 Bucket
Description	Detects repeated failed GetObject attempts against an S3 bucket followed by a successful access from the same source, which can indicate brute-force-style object discovery or access attempts.
Severity	High
Tactics	CredentialAccess
Techniques	T1110
Required data connectors	AWS
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/Amazon%20Web%20Services/Analytic%20Rules/AWS_S3BruteForce.yaml
Version	1.0.2
Arm template	31b9e94b-0df6-4a3d-a297-3457b53c5d86.json

KQL

let timeframe = 1h;
let failed_attempts = AWSCloudTrail
| where TimeGenerated >= ago(timeframe)
| where EventName == "GetObject" and isnotempty(ErrorMessage) and isnotempty(ErrorCode)
| where UserIdentityAccountId == "ANONYMOUS_PRINCIPAL" or UserIdentityAccessKeyId <> RecipientAccountId
| extend UserIdentityArn = iif(isempty(UserIdentityArn), tostring(parse_json(Resources)[0].ARN), UserIdentityArn)
| extend UserName = tostring(split(UserIdentityArn, '/')[-1])
| extend AccountName = case( UserIdentityPrincipalid == "Anonymous", "Anonymous", isempty(UserIdentityUserName), UserName, UserIdentityUserName)
| extend AccountName = iif(AccountName contains "@", tostring(split(AccountName, '@', 0)[0]), AccountName),
  AccountUPNSuffix = iif(AccountName contains "@", tostring(split(AccountName, '@', 1)[0]), "")
| extend bucketName = tostring(parse_json(RequestParameters).bucketName), keyName = tostring(parse_json(RequestParameters).key)
| summarize time_min_failed=arg_min(TimeGenerated, *), failed_keys = dcount(keyName) by RecipientAccountId, AccountName, AccountUPNSuffix, UserIdentityAccountId, SourceIpAddress, bucketName
| where failed_keys > 20;
let success_attempts = AWSCloudTrail
| where TimeGenerated >= ago(timeframe)
| where EventName == "GetObject" and isempty(ErrorMessage) and isempty(ErrorCode)
| where UserIdentityAccountId == "ANONYMOUS_PRINCIPAL" or UserIdentityAccessKeyId <> RecipientAccountId
| extend UserIdentityArn = iif(isempty(UserIdentityArn), tostring(parse_json(Resources)[0].ARN), UserIdentityArn)
| extend UserName = tostring(split(UserIdentityArn, '/')[-1])
| extend AccountName = case( UserIdentityPrincipalid == "Anonymous", "Anonymous", isempty(UserIdentityUserName), UserName, UserIdentityUserName)
| extend AccountName = iif(AccountName contains "@", tostring(split(AccountName, '@', 0)[0]), AccountName),
  AccountUPNSuffix = iif(AccountName contains "@", tostring(split(AccountName, '@', 1)[0]), "")
| extend bucketName = tostring(parse_json(RequestParameters).bucketName), keyName = tostring(parse_json(RequestParameters).key)
| summarize time_min_success=arg_min(TimeGenerated, *), success_keys = dcount(keyName) by RecipientAccountId, AccountName, AccountUPNSuffix, UserIdentityAccountId, SourceIpAddress, bucketName
| where success_keys >= 1;
failed_attempts
| join kind=inner success_attempts on SourceIpAddress, RecipientAccountId, AccountName, AccountUPNSuffix, UserIdentityAccountId, bucketName
| where time_min_success > time_min_failed
| project-away keyName

YAML

requiredDataConnectors:
- dataTypes:
  - AWSCloudTrail
  connectorId: AWS
OriginalUri: https://github.com/Azure/Azure-Sentinel/blob/master/Solutions/Amazon%20Web%20Services/Analytic%20Rules/AWS_S3BruteForce.yaml
version: 1.0.2
status: Available
alertDetailsOverride:
  alertDescriptionFormat: Detected repeated failed and then successful S3 GetObject access for bucket {{bucketName}} in account {{RecipientAccountId}}.
  alertDisplayNameFormat: AWS S3 brute force pattern detected from {{SourceIpAddress}}
customDetails:
  success_keys: success_keys
  failed_keys: failed_keys
  bucketName: bucketName
  RecipientAccountId: RecipientAccountId
queryFrequency: 1h
query: |
  let timeframe = 1h;
  let failed_attempts = AWSCloudTrail
  | where TimeGenerated >= ago(timeframe)
  | where EventName == "GetObject" and isnotempty(ErrorMessage) and isnotempty(ErrorCode)
  | where UserIdentityAccountId == "ANONYMOUS_PRINCIPAL" or UserIdentityAccessKeyId <> RecipientAccountId
  | extend UserIdentityArn = iif(isempty(UserIdentityArn), tostring(parse_json(Resources)[0].ARN), UserIdentityArn)
  | extend UserName = tostring(split(UserIdentityArn, '/')[-1])
  | extend AccountName = case( UserIdentityPrincipalid == "Anonymous", "Anonymous", isempty(UserIdentityUserName), UserName, UserIdentityUserName)
  | extend AccountName = iif(AccountName contains "@", tostring(split(AccountName, '@', 0)[0]), AccountName),
    AccountUPNSuffix = iif(AccountName contains "@", tostring(split(AccountName, '@', 1)[0]), "")
  | extend bucketName = tostring(parse_json(RequestParameters).bucketName), keyName = tostring(parse_json(RequestParameters).key)
  | summarize time_min_failed=arg_min(TimeGenerated, *), failed_keys = dcount(keyName) by RecipientAccountId, AccountName, AccountUPNSuffix, UserIdentityAccountId, SourceIpAddress, bucketName
  | where failed_keys > 20;
  let success_attempts = AWSCloudTrail
  | where TimeGenerated >= ago(timeframe)
  | where EventName == "GetObject" and isempty(ErrorMessage) and isempty(ErrorCode)
  | where UserIdentityAccountId == "ANONYMOUS_PRINCIPAL" or UserIdentityAccessKeyId <> RecipientAccountId
  | extend UserIdentityArn = iif(isempty(UserIdentityArn), tostring(parse_json(Resources)[0].ARN), UserIdentityArn)
  | extend UserName = tostring(split(UserIdentityArn, '/')[-1])
  | extend AccountName = case( UserIdentityPrincipalid == "Anonymous", "Anonymous", isempty(UserIdentityUserName), UserName, UserIdentityUserName)
  | extend AccountName = iif(AccountName contains "@", tostring(split(AccountName, '@', 0)[0]), AccountName),
    AccountUPNSuffix = iif(AccountName contains "@", tostring(split(AccountName, '@', 1)[0]), "")
  | extend bucketName = tostring(parse_json(RequestParameters).bucketName), keyName = tostring(parse_json(RequestParameters).key)
  | summarize time_min_success=arg_min(TimeGenerated, *), success_keys = dcount(keyName) by RecipientAccountId, AccountName, AccountUPNSuffix, UserIdentityAccountId, SourceIpAddress, bucketName
  | where success_keys >= 1;
  failed_attempts
  | join kind=inner success_attempts on SourceIpAddress, RecipientAccountId, AccountName, AccountUPNSuffix, UserIdentityAccountId, bucketName
  | where time_min_success > time_min_failed
  | project-away keyName
tactics:
- CredentialAccess
relevantTechniques:
- T1110
id: 31b9e94b-0df6-4a3d-a297-3457b53c5d86
triggerThreshold: 0
triggerOperator: gt
name: AWSCloudTrail - Successful brute force attack on S3 Bucket
queryPeriod: 1h
severity: High
entityMappings:
- fieldMappings:
  - columnName: AccountName
    identifier: Name
  - columnName: AccountUPNSuffix
    identifier: UPNSuffix
  - columnName: RecipientAccountId
    identifier: CloudAppAccountId
  entityType: Account
- fieldMappings:
  - columnName: SourceIpAddress
    identifier: Address
  entityType: IP
kind: Scheduled
description: |
  Detects repeated failed GetObject attempts against an S3 bucket followed by a successful access from the
  same source, which can indicate brute-force-style object discovery or access attempts.

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/31b9e94b-0df6-4a3d-a297-3457b53c5d86')]",
      "kind": "Scheduled",
      "name": "[concat(parameters('workspace'),'/Microsoft.SecurityInsights/31b9e94b-0df6-4a3d-a297-3457b53c5d86')]",
      "properties": {
        "alertDetailsOverride": {
          "alertDescriptionFormat": "Detected repeated failed and then successful S3 GetObject access for bucket {{bucketName}} in account {{RecipientAccountId}}.",
          "alertDisplayNameFormat": "AWS S3 brute force pattern detected from {{SourceIpAddress}}"
        },
        "alertRuleTemplateName": "31b9e94b-0df6-4a3d-a297-3457b53c5d86",
        "customDetails": {
          "bucketName": "bucketName",
          "failed_keys": "failed_keys",
          "RecipientAccountId": "RecipientAccountId",
          "success_keys": "success_keys"
        },
        "description": "Detects repeated failed GetObject attempts against an S3 bucket followed by a successful access from the\nsame source, which can indicate brute-force-style object discovery or access attempts.\n",
        "displayName": "AWSCloudTrail - Successful brute force attack on S3 Bucket",
        "enabled": true,
        "entityMappings": [
          {
            "entityType": "Account",
            "fieldMappings": [
              {
                "columnName": "AccountName",
                "identifier": "Name"
              },
              {
                "columnName": "AccountUPNSuffix",
                "identifier": "UPNSuffix"
              },
              {
                "columnName": "RecipientAccountId",
                "identifier": "CloudAppAccountId"
              }
            ]
          },
          {
            "entityType": "IP",
            "fieldMappings": [
              {
                "columnName": "SourceIpAddress",
                "identifier": "Address"
              }
            ]
          }
        ],
        "OriginalUri": "https://github.com/Azure/Azure-Sentinel/blob/master/Solutions/Amazon%20Web%20Services/Analytic%20Rules/AWS_S3BruteForce.yaml",
        "query": "let timeframe = 1h;\nlet failed_attempts = AWSCloudTrail\n| where TimeGenerated >= ago(timeframe)\n| where EventName == \"GetObject\" and isnotempty(ErrorMessage) and isnotempty(ErrorCode)\n| where UserIdentityAccountId == \"ANONYMOUS_PRINCIPAL\" or UserIdentityAccessKeyId <> RecipientAccountId\n| extend UserIdentityArn = iif(isempty(UserIdentityArn), tostring(parse_json(Resources)[0].ARN), UserIdentityArn)\n| extend UserName = tostring(split(UserIdentityArn, '/')[-1])\n| extend AccountName = case( UserIdentityPrincipalid == \"Anonymous\", \"Anonymous\", isempty(UserIdentityUserName), UserName, UserIdentityUserName)\n| extend AccountName = iif(AccountName contains \"@\", tostring(split(AccountName, '@', 0)[0]), AccountName),\n  AccountUPNSuffix = iif(AccountName contains \"@\", tostring(split(AccountName, '@', 1)[0]), \"\")\n| extend bucketName = tostring(parse_json(RequestParameters).bucketName), keyName = tostring(parse_json(RequestParameters).key)\n| summarize time_min_failed=arg_min(TimeGenerated, *), failed_keys = dcount(keyName) by RecipientAccountId, AccountName, AccountUPNSuffix, UserIdentityAccountId, SourceIpAddress, bucketName\n| where failed_keys > 20;\nlet success_attempts = AWSCloudTrail\n| where TimeGenerated >= ago(timeframe)\n| where EventName == \"GetObject\" and isempty(ErrorMessage) and isempty(ErrorCode)\n| where UserIdentityAccountId == \"ANONYMOUS_PRINCIPAL\" or UserIdentityAccessKeyId <> RecipientAccountId\n| extend UserIdentityArn = iif(isempty(UserIdentityArn), tostring(parse_json(Resources)[0].ARN), UserIdentityArn)\n| extend UserName = tostring(split(UserIdentityArn, '/')[-1])\n| extend AccountName = case( UserIdentityPrincipalid == \"Anonymous\", \"Anonymous\", isempty(UserIdentityUserName), UserName, UserIdentityUserName)\n| extend AccountName = iif(AccountName contains \"@\", tostring(split(AccountName, '@', 0)[0]), AccountName),\n  AccountUPNSuffix = iif(AccountName contains \"@\", tostring(split(AccountName, '@', 1)[0]), \"\")\n| extend bucketName = tostring(parse_json(RequestParameters).bucketName), keyName = tostring(parse_json(RequestParameters).key)\n| summarize time_min_success=arg_min(TimeGenerated, *), success_keys = dcount(keyName) by RecipientAccountId, AccountName, AccountUPNSuffix, UserIdentityAccountId, SourceIpAddress, bucketName\n| where success_keys >= 1;\nfailed_attempts\n| join kind=inner success_attempts on SourceIpAddress, RecipientAccountId, AccountName, AccountUPNSuffix, UserIdentityAccountId, bucketName\n| where time_min_success > time_min_failed\n| project-away keyName\n",
        "queryFrequency": "PT1H",
        "queryPeriod": "PT1H",
        "severity": "High",
        "status": "Available",
        "subTechniques": [],
        "suppressionDuration": "PT1H",
        "suppressionEnabled": false,
        "tactics": [
          "CredentialAccess"
        ],
        "techniques": [
          "T1110"
        ],
        "templateVersion": "1.0.2",
        "triggerOperator": "GreaterThan",
        "triggerThreshold": 0
      },
      "type": "Microsoft.OperationalInsights/workspaces/providers/alertRules"
    }
  ]
}