detection.wiki

Detection rules › Panther

AWS S3 Unauthenticated Access

Severity
low
Log types
AWS.S3ServerAccess
Tags
AWS, Configuration Required, Security Control, Collection:Data From Cloud Storage Object
Reference
https://docs.aws.amazon.com/AmazonS3/latest/userguide/access-control-auth-workflow-bucket-operation.html
Source
github.com/panther-labs/panther-analysis

Checks for S3 access attempts where the requester is not an authenticated AWS user.

MITRE ATT&CK coverage

TacticTechniques
CollectionT1530 Data from Cloud Storage

Rule body yaml

AnalysisType: rule
Filename: aws_s3_unauthenticated_access.py
RuleID: "AWS.S3.ServerAccess.Unauthenticated"
DisplayName: "AWS S3 Unauthenticated Access"
Enabled: false
LogTypes:
  - AWS.S3ServerAccess
Tags:
  - AWS
  - Configuration Required
  - Security Control
  - Collection:Data From Cloud Storage Object
Reports:
  MITRE ATT&CK:
    - TA0009:T1530
Severity: Low
Description: >
  Checks for S3 access attempts where the requester is not an authenticated AWS user.
Runbook: >
  If unauthenticated S3 access is not expected for this bucket, update its access policies.
Reference: https://docs.aws.amazon.com/AmazonS3/latest/userguide/access-control-auth-workflow-bucket-operation.html
SummaryAttributes:
  - bucket
  - key
  - requester
Tests:
  - Name: Authenticated Access
    ExpectedResult: false
    Log:
      {
        "bucket": "example-bucket",
        "requester": "79a59df900b949e55d96a1e698fbacedfd6e09d98eacf8f8d5218e7cd47ef2be",
      }
  - Name: Unauthenticated Access
    ExpectedResult: true
    Log: { "bucket": "example-bucket" }

Detection logic

Condition

bucket in "example-bucket"
requester is_null

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.

FieldKindValues
bucketin
  • example-bucket
requesteris_null
  • (no value, null check)

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
eventName
eventSource
awsRegion
recipientAccountId
sourceIPAddress
userAgent
userIdentity
bucket