User-Assigned Managed Identities for Azure Functions

ID: azure-functionapp-user-assigned-id-missing

Severity: medium

Author: princechaddha

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

Description

Ensure that functions managed with Azure Function App are using user-assigned managed identities for fine-grained control over access permissions.

YAML Source

id: azure-functionapp-user-assigned-id-missing
info:
  name: User-Assigned Managed Identities for Azure Functions
  author: princechaddha
  severity: medium
  description: |
    Ensure that functions managed with Azure Function App are using user-assigned managed identities for fine-grained control over access permissions.
  impact: |
    Using default or system-assigned identities can limit the granularity of access control, potentially allowing broader than necessary access to resources.
  remediation: |
    Configure user-assigned managed identities for your Azure Function Apps to gain more granular control over permissions and reduce potential security risks.
  reference:
    - https://docs.microsoft.com/en-us/azure/app-service/overview-managed-identity
  tags: cloud,devops,azure,microsoft,functionapp,azure-cloud-config

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

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

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

  - engine:
      - sh
      - bash
    source: |
      az functionapp show --name $name --resource-group $resourceGroup --query 'identity.type' --output json

    matchers:
      - type: word
        words:
          - "SystemAssigned"
          - ""

    extractors:
      - type: dsl
        dsl:
          - 'name + " does not use user-assigned managed identity"'
# digest: 4b0a0048304602210085a1797351e11b25bb80977ade24a774f0fd6b2015ab8177c9d7c321a326709a022100ca38ed41d8ef5d584b0a171a9e715917b323113933aab88a067c7ee58773f73b: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/functions/azure-functionapp-user-assigned-id-missing.yaml"

View on Github