Azure Function App Exploitation
Discover vulnerabilities in Azure Function Apps and learn how to exploit them.
Lab Objectives
- Understand Azure Function App security features and potential vulnerabilities
- Learn techniques to enumerate and identify vulnerable Function Apps
- Exploit common misconfigurations in Function Apps
- Implement security best practices for Azure Function Apps
Prerequisites
- Advanced understanding of Azure Functions and serverless concepts
- Familiarity with Azure CLI, PowerShell, and Azure SDKs
- Basic knowledge of web application security
- Access to an Azure test environment with Function Apps deployed
Lab Steps
Step 1: Enumerating Azure Function Apps
In this step, we'll use various techniques to enumerate Azure Function Apps in the target environment. 1. Using Azure CLI to list Function Apps: ```bash az functionapp list --query "[].{Name:name, ResourceGroup:resourceGroup, DefaultHostName:defaultHostName}" -o table ``` 2. Enumerate Function App settings: ```bash az functionapp config appsettings list --name <function-app-name> --resource-group <resource-group> --query "[].{Name:name, Value:value}" -o table ``` 3. List Function App functions: ```bash az functionapp function list --name <function-app-name> --resource-group <resource-group> --query "[].{Name:name, Language:language}" -o table ``` 4. Use Azure PowerShell to get Function App details: ```powershell Get-AzFunctionApp -Name <function-app-name> -ResourceGroupName <resource-group> | Format-List ``` Analyze the output to identify potential vulnerabilities and misconfigurations in the Function App setup.
Step 2: Exploiting Function App Misconfigurations
Now that we've identified potential vulnerabilities, let's exploit common misconfigurations in Azure Function Apps. 1. Exploiting insecure authentication: - Identify Function Apps with anonymous access enabled - Attempt to access sensitive functions without authentication: ```bash curl https://<function-app-name>.azurewebsites.net/api/<function-name> ``` 2. Leveraging overly permissive CORS settings: - Identify Function Apps with permissive CORS policies - Create a simple web page to demonstrate cross-origin access: ```html <!DOCTYPE html> <html> <body> <script> fetch('https://<function-app-name>.azurewebsites.net/api/<function-name>', { method: 'GET', mode: 'cors' }) .then(response => response.text()) .then(data => console.log(data)) .catch(error => console.error('Error:', error)); </script> </body> </html> ``` 3. Exploiting environment variable leakage: - Check for sensitive information in environment variables - Use the Azure CLI to list app settings: ```bash az functionapp config appsettings list --name <function-app-name> --resource-group <resource-group> --query "[?name=='WEBSITE_LOAD_CERTIFICATES']" ``` 4. Leveraging function runtime vulnerabilities: - Identify outdated function runtime versions - Research known vulnerabilities for the specific version and attempt to exploit them 5. Exploiting insecure dependencies: - Analyze the function's dependencies for known vulnerabilities - Use tools like OWASP Dependency-Check to scan for vulnerable components Remember to document all findings and potential vulnerabilities discovered during the exploitation phase.
Step 3: Implementing Security Best Practices
To secure Azure Function Apps, implement the following best practices: ... (rest of the content) 8. Implement input validation and output encoding in your functions: ```javascript module.exports = async function (context, req) { const name = context.bindingData.name; // Input validation if (!/^[a-zA-Z0-9]+$/.test(name)) { context.res = { status: 400, body: "Invalid input: name must be alphanumeric" }; return; } // Output encoding const encodedName = encodeURIComponent(name); context.res = { body: `Hello, ${encodedName}!` }; }; ``` ... (rest of the content)