azure-nsg-cifs-unrestricted: Unrestricted CIFS Access in Azure NSGs

id: azure-nsg-cifs-unrestricted
info:
  name: Unrestricted CIFS Access in Azure NSGs
  author: princechaddha
  severity: high
  description: |
    Ensure that Microsoft Azure network security groups (NSGs) do not allow unrestricted access on TCP port 445, used by Common Internet File System (CIFS), to prevent unauthorized access.
  impact: |
    Unrestricted access on TCP port 445 can expose network resources to risks such as unauthorized data access and data theft.
  remediation: |
    Modify NSG rules to restrict access on TCP port 445. Only allow known IPs, and consider implementing stronger security measures for sensitive file transfers.
  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=='TCP' && (destinationPortRange=='445')]"

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

    extractors:
      - type: dsl
        dsl:
          - 'nsg + " has unrestricted access on TCP port 445"'
# digest: 4a0a0047304502200ff7aed9f297814db0f36856e6bd6d32b2bed920955fd728ea4551af25b775d502210090983432a86c2dd81e3c8b97d6523e922eb9587df5ba286bbae2fa8b0688a515:922c64590222798bb761d5b6d8e72950

# Visit https://trap.biu.life/ to view exploit trends for this vulnerability.