S3 Bucket with Public WRITE Access

ID: s3-public-write

Severity: critical

Author: princechaddha

Tags: cloud,devops,aws,amazon,s3,aws-cloud-config

Description

Checks if Amazon S3 buckets are secured against public WRITE access, preventing unauthorized modifications to access control permissions.

YAML Source

id: s3-public-write
info:
  name: S3 Bucket with Public WRITE Access
  author: princechaddha
  severity: critical
  description: |
    Checks if Amazon S3 buckets are secured against public WRITE access, preventing unauthorized modifications to access control permissions.
  reference:
    - https://docs.aws.amazon.com/cli/latest/reference/s3api/get-bucket-acl.html
  metadata:
    max-request: 2
  tags: cloud,devops,aws,amazon,s3,aws-cloud-config

flow: |
  code(1)
  for(let bucketName of iterate(template.buckets)){
    set("bucket", bucketName)
    code(2)
  }

self-contained: true
code:
  - engine:
      - sh
      - bash
    source: |
      aws s3api list-buckets --query 'Buckets[*].Name'

    extractors:
      - type: json # type of the extractor
        internal: true
        name: buckets
        json:
          - '.[]'

  - engine:
      - sh
      - bash
    source: |
        aws s3api get-bucket-acl --bucket $bucket --query 'Grants[?(Grantee.URI==`http://acs.amazonaws.com/groups/global/AllUsers`)]'

    matchers:
      - type: word
        words:
          - '"Permission": "WRITE"'

    extractors:
      - type: dsl
        dsl:
          - '"The S3 bucket " + bucket +" have public WRITE access"'
# digest: 4b0a00483046022100d99877590e07d7434dce5334e556640c79137c44c1364159f577d1cb4e7ea6c60221009aaa5f2b574545b10e528d89cc49c9d1c7b6ebbfe35467b3d948ec9a7a36b935:922c64590222798bb761d5b6d8e72950

Guide to check the vulnerabilities

This template is used to detect vulnerabilities in web applications. It can be used with the Nuclei tool to scan for specific patterns or behaviors.

$ nuclei -u "URL" -t "cloud/aws/s3/s3-public-write.yaml"

View on Github