TL;DR
This guide shows you how to authenticate with OWASP ZAP using a script, allowing it to scan protected areas of your web application. We’ll cover setting up the script and testing it.
Setting Up Authentication in ZAP
Open Your Script: In ZAP, go to Tools > Options.
Navigate to Scripts: Select the ‘Scripts’ tab.
Add a New Script: Click ‘Add’. Give your script a meaningful name (e.g., ‘MyAuthenticationScript’). Choose a suitable language (JavaScript is common).
Writing the Authentication Script
The core of authentication lies in the script itself. Here’s an example using JavaScript to handle basic HTTP authentication:
function scan(helper, ctx) {
var request = helper.request;
// Check if the request needs authentication (e.g., by URL)
if (request.getURL().toString().startsWith(“https://your-protected-app/admin/”)) {
// Add Authentication Header
request.addHeader(“Authorization”, “Basic ” + helper.getAuthenticationToken());
}
}
Explanation:
scan(helper, ctx): This function is called for each request ZAP intercepts.
helper.request: Provides access to the current HTTP request object.
request.getURL().toString(): Gets the URL of the request as a string.
startsWith(“https://your-protected-app/admin/”): Checks if the URL starts with your protected application’s admin path. Replace this with your actual URL!
request.addHeader(“Authorization”, “Basic ” + helper.getAuthenticationToken()): Adds an ‘Authorization’ header to the request, including a basic authentication token. The helper.getAuthenticationToken() function is crucial; we’ll define this next.
Getting the Authentication Token
You need a way for ZAP to obtain the authentication token (username/password). Here’s how you can implement that:
function getAuthenticationToken() {
// Prompt user for credentials if not already cached.
var username = ctx.getOption(“authentication.username”);
var password = ctx.getOption(“authentication.password”);
if (!username || !password) {
var dialog = new Dialog();
dialog.setTitle(“Authentication Required”);
dialog.setPromptText(“Username:”, username);
dialog.setPromptText(“Password:”, password);
dialog.showDialog();
username = dialog.getValue(“Username”);
password = dialog.getValue(“Password”);
ctx.setOption(“authentication.username”, username);
ctx.setOption(“authentication.password”, password);
}
// Encode the credentials in Base64.
var encodedCredentials = btoa(username + ‘:’ + password);
return encodedCredentials;
}
Explanation:
ctx.getOption(“authentication.username”) and ctx.getOption(“authentication.password”): Attempts to retrieve cached credentials from ZAP’s options.
The if (!username || !password) block prompts the user for credentials if they aren’t already stored.
btoa(username + ‘:’ + password): Encodes the username and password in Base64, which is required for Basic Authentication.
Adding the Token Function to Your Script
Add the getAuthenticationToken() function to your script *before* the scan() function.
Testing the Script
Save Your Script: Save the changes to your authentication script.
Enable the Script: In ZAP, ensure the script is enabled (checkbox ticked in the Scripts tab).
Browse Your Application: Start browsing your protected application. ZAP will intercept requests and apply the authentication header if it matches your URL condition.
Check the History Tab: Verify that the ‘Authorization’ header is being added to requests targeting your protected areas in ZAP’s History tab. Select a request, then look at the ‘Request’ tab. You should see the header present.
Troubleshooting
Incorrect URL: Double-check that the URL condition in your script (startsWith()) is correct.
Base64 Encoding: Ensure the username and password are correctly encoded in Base64.
Authentication Type: This example uses Basic Authentication. Adjust the script if your application uses a different authentication method (e.g., API keys, OAuth).
The post ZAP Script Authentication: A Step-by-Step Guide appeared first on Blog | G5 Cyber Security.
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