Unrestricted ICMP Access in Azure NSGs

ID: azure-nsg-icmp-unrestricted

Severity: high

Author: princechaddha

Tags: cloud,devops,azure,microsoft,nsg,azure-cloud-config

Description

Ensure that Microsoft Azure network security groups (NSGs) do not allow unrestricted inbound access using Internet Control Message Protocol (ICMP) to prevent potential network-related attacks.

YAML Source

id: azure-nsg-icmp-unrestricted
info:
  name: Unrestricted ICMP Access in Azure NSGs
  author: princechaddha
  severity: high
  description: |
    Ensure that Microsoft Azure network security groups (NSGs) do not allow unrestricted inbound access using Internet Control Message Protocol (ICMP) to prevent potential network-related attacks.
  impact: |
    Allowing unrestricted ICMP access can expose the network to various threats, including Denial of Service (DoS) attacks and network mapping.
  remediation: |
    Configure NSG rules to restrict ICMP traffic. Only allow necessary ICMP types and codes and monitor ICMP activity to detect unusual patterns.
  reference:
    - https://docs.microsoft.com/en-us/azure/virtual-network/network-security-groups-overview
  tags: cloud,devops,azure,microsoft,nsg,azure-cloud-config

flow: |
  code(1);
  for (let NsgData of iterate(template.nsgdata)) {
    NsgData = JSON.parse(NsgData)
    set("nsg", NsgData.name)
    set("resourcegroup", NsgData.resourceGroup)
    code(2)
  }

self-contained: true
code:
  - engine:
      - sh
      - bash
    source: |
      az network nsg list --query '[*].{name:name, resourceGroup:resourceGroup}' --output json

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

  - engine:
      - sh
      - bash
    source: |
      az network nsg rule list --nsg-name $nsg --resource-group $resourcegroup --query "[?direction=='Inbound' && access=='Allow' && protocol=='ICMP']"

    matchers:
      - type: word
        words:
          - '"sourceAddressPrefix": "*"'
          - '"sourceAddressPrefix": "internet"'
          - '"sourceAddressPrefix": "any"'

    extractors:
      - type: dsl
        dsl:
          - 'nsg + " has unrestricted access using ICMP"'
# digest: 4a0a0047304502210089b438f4ae1214e14e544ed586d1f4f1a0c9eb9dcd6287fec843530077218d0302202f9fa9ad71a860caa87ce4ed5dc05979444f79a1ce6076a1fb1cb85c2c4b8f7d: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/azure/network/azure-nsg-icmp-unrestricted.yaml"

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