AWS Cloudtrail Region Enabled

Severity: medium
Log types: AWS.CloudTrail
Tags: AWS, CloudTrail, Region
Reference: https://permiso.io/blog/how-threat-actors-leverage-unsupported-cloud-regions
Source: github.com/panther-labs/panther-analysis

Threat actors who successfully compromise a victim's AWS account, whether through stolen credentials, exposed access keys, exploited IAM misconfigurations, vulnerabilities in third-party applications, or the absence of Multi-Factor Authentication (MFA), can exploit unused regions as safe zones for malicious activities. These regions are often overlooked in monitoring and security setups, making them an attractive target for attackers to operate undetected.

MITRE ATT&CK coverage

Tactic	Techniques
Stealth	`T1535` Unused/Unsupported Cloud Regions

Rule body yaml

AnalysisType: rule
DedupPeriodMinutes: 60
DisplayName: AWS Cloudtrail Region Enabled
Enabled: true
Filename: aws_cloudtrail_region_enabled.py
RuleID: "AWS.CloudTrail.EnableRegion"
Severity: Medium
LogTypes:
  - AWS.CloudTrail
Tags:
  - AWS
  - CloudTrail
  - Region
Reports:
    MITRE ATT&CK:
        - TA0005:T1535  # Unused/Unsupported Cloud Regions
Description: >
  Threat actors who successfully compromise a victim's AWS account, whether through stolen credentials, 
  exposed access keys, exploited IAM misconfigurations, vulnerabilities in third-party applications, 
  or the absence of Multi-Factor Authentication (MFA), can exploit unused regions as safe zones 
  for malicious activities. These regions are often overlooked in monitoring and security setups, 
  making them an attractive target for attackers to operate undetected.
Runbook: |
  Validate whether enabling the new region was authorized.  
  Revoke user privileges, review the newly enabled region for malicious activity, and disable the region.
Reference: https://permiso.io/blog/how-threat-actors-leverage-unsupported-cloud-regions
Tests:
  - Name: EnableRegion
    LogType: AWS.CloudTrail
    ExpectedResult: true
    Log:
      {
        "eventVersion": "1.08",
        "userIdentity": {
          "type": "IAMUser",
          "principalId": "EXAMPLE",
          "arn": "arn:aws:iam::123456789012:user/Alice",
          "accountId": "123456789012",
          "accessKeyId": "EXAMPLEKEY",
          "userName": "Alice"
        },
        "eventTime": "2023-10-01T12:34:56Z",
        "eventSource": "cloudtrail.amazonaws.com",
        "eventName": "EnableRegion",
        "awsRegion": "us-east-1",
        "sourceIPAddress": "192.0.2.0",
        "userAgent": "aws-sdk-go/1.15.12 (go1.12.6; linux; amd64)",
        "requestParameters": {
          "RegionName": "us-west-2"
        },
        "responseElements": null,
        "additionalEventData": {
          "SignatureVersion": "SigV4",
          "CipherSuite": "ECDHE-RSA-AES128-GCM-SHA256",
          "bytesTransferredIn": 0,
          "bytesTransferredOut": 0
        },
        "requestID": "EXAMPLE123456789",
        "eventID": "EXAMPLE-1234-5678-9012-EXAMPLE",
        "readOnly": false,
        "resources": [],
        "eventType": "AwsApiCall",
        "managementEvent": false,
        "recipientAccountId": "123456789012",
        "sharedEventID": "EXAMPLE-1234-5678-9012-EXAMPLE",
        "vpcEndpointId": "vpce-1a2b3c4d"
      }
  - Name: Other Event
    LogType: AWS.CloudTrail
    ExpectedResult: false
    Log:
      {
        "eventVersion": "1.08",
        "userIdentity": {
          "type": "IAMUser",
          "principalId": "EXAMPLE",
          "arn": "arn:aws:iam::123456789012:user/Bob",
          "accountId": "123456789012",
          "accessKeyId": "EXAMPLEKEY",
          "userName": "Bob"
        },
        "eventTime": "2023-10-01T12:34:56Z",
        "eventSource": "s3.amazonaws.com",
        "eventName": "ListBucket",
        "awsRegion": "us-east-1",
        "sourceIPAddress": "192.0.2.0",
        "userAgent": "aws-sdk-go/1.15.12 (go1.12.6; linux; amd64)",
        "requestParameters": {
          "bucketName": "example-bucket"
        },
        "responseElements": null,
        "additionalEventData": {
          "SignatureVersion": "SigV4",
          "CipherSuite": "ECDHE-RSA-AES128-GCM-SHA256",
          "bytesTransferredIn": 0,
          "bytesTransferredOut": 0
        },
        "requestID": "EXAMPLE123456789",
        "eventID": "EXAMPLE-1234-5678-9012-EXAMPLE",
        "readOnly": true,
        "resources": [
          {
            "type": "AWS::S3::Bucket",
            "ARN": "arn:aws:s3:::example-bucket"
          }
        ],
        "eventType": "AwsApiCall",
        "managementEvent": false,
        "recipientAccountId": "123456789012",
        "sharedEventID": "EXAMPLE-1234-5678-9012-EXAMPLE",
        "vpcEndpointId": "vpce-1a2b3c4d"
      }

Detection logic

Condition

eventName eq "EnableRegion"

Indicators

Each row is a field, operator, and value that the rule matches. The corpus column counts how many other rules in the catalog look for the same combination: high numbers point to widely-used, community-vetted indicators. Blank or 1 shows that the indicator is specific to this rule.

Field	Kind	Values
`eventName`	eq	`EnableRegion`

Output fields

Fields the rule emits when it matches. Chronicle authors list these in the outcome block; they appear on the detection and $risk_score drives alerting. Sentinel / Defender XDR rules build them up through project / summarize / extend stages. Sentinel maps these into alert fields via entityMappings and customDetails; Defender XDR custom detections surface them as alert fields directly.

Field	Source
`eventName`
`eventSource`
`awsRegion`
`recipientAccountId`
`sourceIPAddress`
`userAgent`
`userIdentity`
`RegionName`	`requestParameters.RegionName`
`actor_user`

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`type:`	`events` / `rules` / `providers`
`vendor:`	`sigma` / `elastic` / `splunk` / `kusto` / `chronicle` (vendor name alone also works: `sigma:`, `kql:`, `secops:`…)
`tactic:`	TA-id, slug, or name: `credential_access`, `TA0006`
`technique:`	technique or sub-technique ID: `T1003`, `T1003.001` (alias `tech:`)
`severity:`	`critical` / `high` / `medium` / `low` / `informational` (alias `sev:`)
`risk_score`	Numeric comparison on the Elastic risk score (0 to 100): `risk_score>50`, `risk_score<=20`, `risk_score=99` (alias `risk`; Elastic rules only)
`stages:`	Rules with exactly N pipeline stages
`correlation:`	`single_event` / `sequence` / `alternatives` / `alternatives_cross_log` / `all_required` / `correlated`
`with:`	Co-occurrence event-id; stacks (`with:4624 with:4769`) to require all, while a comma list in one occurrence (`with:4624,4769`) is an either-or group. Implies multi-event
`like:`	Structural neighbors of a rule slug (equivalents + subsumption stricter / broader): `like:comsvcs_lsass_memory_dump-splunk-sysmon`
`groupby:`	Entity-grouping substring match against `group_by_keys`: `groupby:user`, `groupby:host`
`uses:`	Rules whose predicate tree touches the field (any kind, any value): `uses:CommandLine`
`excludes:`	Rules with top-level `not()` clauses on the field (FP whitelists): `excludes:ParentImage`
`field:` / `value:`	Predicate search; narrows rule cards to those with a matching leaf and drives the indicator tier. Unquoted = substring, wildcards allowed (`value:mimikatz`)
`indicator:`	Shorthand for `field:F value:V`: `indicator:Image=*\powershell.exe`
`kind:`	Filter by predicate kind. Narrows rule cards to those carrying a matching predicate leaf (`vendor:elastic kind:cidr_match`) and drives the indicator tier: `contains` / `starts_with` / `ends_with` / `regex` / `cidr` / `eq` / `in` … (operator aliases `op:`/`match:`)
`has:` / `no:`	`sample`, `field`, `notes`, `refs`, `trace`, `thirdparty`, `rule`, `pattern`, `timewindow`, `threshold`, `newterms`, `sigma`/`elastic`/`splunk`/`kusto`/`chronicle`
`-op:val`	Exclude matches; works on most operators but not `type:`/`like:`/`has:`/`no:` (use `no:<flag>` to exclude a rule flag): `tactic:execution -vendor:splunk`. Standalone `-kind:`/`-field:`/`-value:` drop every rule carrying a matching predicate leaf (`type:rules -kind:is_null`)
`field:"…"` / `value:"…"`	Quoted value = anchored exact match (also allows spaces): `value:"net user"`
`a,b`	Comma = OR inside one operator (`vendor:sigma,elastic`, `severity:high,critical`); repeating a facet merges the same way. `field:`/`value:` never split (literal commas)
`vendors:` / `stage:`	Singular and plural spellings fold to the canonical operator and value: `tactics:` = `tactic:`, `type:event` = `type:events`, `correlation:sequences` = `correlation:sequence`, `has:thresholds` = `has:threshold`
`"quoted phrase"`	Exact-match a multi-word phrase (free text)