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Nuclei Templates

Unrestricted SMTP Access in EC2

ID: ec2-unrestricted-smtp

Severity: critical

Author: princechaddha

Tags: cloud,devops,aws,amazon,ec2,aws-cloud-config

Description

Section titled “Description”

Identifies unrestricted inbound access on TCP port 25 for EC2 security groups, which increases the risk of SMTP-related attacks.

YAML Source

Section titled “YAML Source”
id: ec2-unrestricted-smtp
info:
  name: Unrestricted SMTP Access in EC2
  author: princechaddha
  severity: critical
  description: |
    Identifies unrestricted inbound access on TCP port 25 for EC2 security groups, which increases the risk of SMTP-related attacks.
  impact: |
    Allowing unrestricted SMTP access can lead to spamming, mail relay abuse, and potentially compromise mail servers.
  remediation: |
    Restrict TCP port 25 access to known, necessary IP addresses only. Avoid using 0.0.0.0/0 or ::/0 in security group rules.
  reference:
    - https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/authorizing-access-to-an-instance.html
  tags: cloud,devops,aws,amazon,ec2,aws-cloud-config


variables:
  region: "us-east-1"


self-contained: true
code:
  - engine:
      - sh
      - bash
    source: |
      aws ec2 describe-security-groups --region $region --filters Name=ip-permission.from-port,Values=25 Name=ip-permission.to-port,Values=25 Name=ip-permission.cidr,Values='0.0.0.0/0' --output json --query 'SecurityGroups[*].GroupId'


    extractors:
      - type: json
        name: securitygroup
        internal: true
        json:
          - '.[]'


      - type: dsl
        dsl:
          - 'securitygroup + " security group(s) alows unrestricted access (0.0.0.0/0 or ::/0) on TCP port 25"'
# digest: 490a0046304402203bfae3cd9ef508cefed1bc32dd02dfc1175acd449fd1ba9bf16d82338cc2f3110220134c0b49bd49e77281b4011b48739cc645fc2223c80eace3af80ea52fe36f24e:922c64590222798bb761d5b6d8e72950

Guide to check the vulnerabilities

Section titled “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.

Terminal window
$ nuclei -u "URL" -t "cloud/aws/ec2/ec2-unrestricted-smtp.yaml"

View on Github