Mitigation Strategy: Simulate Content Security Policy (CSP)
Mitigation Strategy: Simulate Content Security Policy (CSP)
* **Description:**
1. **Identify Dangerous Functions:** Determine which JavaScript functions are most likely to be abused in attacks (e.g., `eval`, `setTimeout` with string arguments, `document.write`, `innerHTML`, `Function` constructor).
2. **Create Override Scripts:** Write JavaScript code that overrides these dangerous functions. The overrides should:
* Log any attempts to use the original function.
* Implement safer alternatives, if possible (e.g., use `JSON.parse` instead of `eval` for parsing JSON).
* Throw an error or simply do nothing to prevent the original function from executing.
3. **Inject Override Scripts:** Use PhantomJS's `page.evaluate` function to inject the override scripts *before* any other JavaScript code is executed on the page. This is crucial for preventing race conditions. You can do this within the `onInitialized` callback. Example:
```javascript
page.onInitialized = function() {
page.evaluate(function() {
window.eval = function() {
console.log("eval blocked!");
throw new Error("eval is not allowed.");
};
// Override other functions similarly...
});
};
```
4. **Resource Whitelisting (onResourceRequested):** Use the `onResourceRequested` callback to inspect each resource request made by PhantomJS.
* Check the URL of the requested resource against a whitelist of allowed domains and resource types.
* If the resource is not allowed, use `request.abort()` to block the request. Example:
```javascript
page.onResourceRequested = function(requestData, networkRequest) {
var allowedDomains = ["example.com", "cdn.example.com"];
var url = new URL(requestData.url);
if (allowedDomains.indexOf(url.hostname) === -1) {
console.log("Request blocked: " + requestData.url);
networkRequest.abort();
}
};
```
5. **Combine with URL validation:** Use this strategy with strict URL validation.
* **Threats Mitigated:**
* **Cross-Site Scripting (XSS) (Severity: High):** By overriding potentially dangerous functions and controlling resource loading, you make it harder for attackers to inject and execute malicious JavaScript.
* **Remote Code Execution (RCE) (Severity: Critical):** Limiting the capabilities of JavaScript within PhantomJS reduces the impact of vulnerabilities that rely on JavaScript execution.
* **Impact:**
* **XSS:** Risk reduced. The effectiveness of XSS attacks is limited.
* **RCE:** Risk reduced. The attacker's ability to execute arbitrary code is constrained.
* **Currently Implemented:** Not implemented.
* **Missing Implementation:**
* No override scripts are created or injected.
* The `onResourceRequested` callback is not used for resource whitelisting.
Mitigation Strategy: Set Timeout Limits
Mitigation Strategy: Set Timeout Limits
* **Description:**
1. **Identify Time-Consuming Operations:** Determine which PhantomJS operations are most likely to take a significant amount of time (e.g., page loading, script execution, rendering).
2. **Set `page.settings.resourceTimeout`:** Use this setting to specify a maximum time (in milliseconds) for PhantomJS to wait for a resource to load. If the timeout is exceeded, the resource request is aborted. Example:
```javascript
page.settings.resourceTimeout = 5000; // 5 seconds
```
3. **Set `page.settings.operationTimeout`:** Use this setting to specify the maximum time for the whole operation.
```javascript
page.settings.operationTimeout = 30000; // 30 seconds
```
4. **Implement Script Timeouts (if applicable):** If you're executing custom JavaScript within PhantomJS using `page.evaluate`, implement timeouts within your script logic to prevent long-running or infinite loops. This requires careful coding within the `page.evaluate` block.
5. **Handle Timeouts Gracefully:** In your application code (outside of PhantomJS), handle timeout errors from PhantomJS gracefully. Log the timeout, terminate the PhantomJS process, and potentially retry the operation (with caution). This is handled by the wrapper library or your process management code.
6. **Use wrapper library timeout:** If you are using wrapper library, use its timeout functionality.
* **Threats Mitigated:**
* **Denial of Service (DoS) (Severity: High):** Timeouts prevent PhantomJS from being stuck indefinitely on a slow or malicious page, preventing resource exhaustion.
* **Resource Exhaustion (Severity: High):** Timeouts limit the amount of time PhantomJS can consume resources.
* **Impact:**
* **DoS:** Risk significantly reduced. PhantomJS cannot be used to tie up resources indefinitely.
* **Resource Exhaustion:** Risk reduced. Resource consumption is limited.
* **Currently Implemented:** Partially. `page.settings.resourceTimeout` is set to 5 seconds.
* **Missing Implementation:**
* `page.settings.operationTimeout` is not set.
* Script-level timeouts are not implemented within `page.evaluate` calls.
Mitigation Strategy: Disable JavaScript (If Possible)
Mitigation Strategy: Disable JavaScript (If Possible)
* **Description:**
1. **Assess JavaScript Dependency:** Carefully analyze your application's use of PhantomJS. Determine if JavaScript execution is *absolutely essential*. If you're only using PhantomJS for taking screenshots of static content or extracting basic HTML structure, JavaScript might not be needed.
2. **Use Command-Line Option:** When launching PhantomJS, use the `--load-images=false --ignore-ssl-errors=true --ssl-protocol=any --web-security=false` command-line option to disable JavaScript execution. This is a *command-line argument*, not a setting within the PhantomJS script.
3. **Test Thoroughly:** After disabling JavaScript, thoroughly test your application to ensure that it still functions correctly. Many websites rely heavily on JavaScript, so this option may not be viable in many cases.
* **Threats Mitigated:**
* **Cross-Site Scripting (XSS) (Severity: High):** Disabling JavaScript completely eliminates the risk of XSS attacks.
* **Remote Code Execution (RCE) (Severity: Critical):** Many RCE vulnerabilities in PhantomJS rely on exploiting JavaScript engine bugs. Disabling JavaScript significantly reduces the attack surface.
* **Impact:**
* **XSS:** Risk eliminated (if JavaScript is truly not needed).
* **RCE:** Risk significantly reduced.
* **Currently Implemented:** Not implemented. The application requires JavaScript for rendering dynamic content.
* **Missing Implementation:** JavaScript is currently enabled. The feasibility of disabling it needs to be re-evaluated, as the application's requirements may have changed.
Mitigation Strategy: Disable Plugins
Mitigation Strategy: Disable Plugins
* **Description:**
1. **Assess Plugin Dependency:** Determine if your PhantomJS usage requires any plugins (e.g., Flash). In most modern web scenarios, plugins are unnecessary.
2. **Use Command-Line Option:** When launching PhantomJS, use the `--load-plugins=false` command-line option to disable plugin loading. This is a *command-line argument*.
3. **Test Thoroughly:** After disabling plugins, thoroughly test to ensure no required functionality is broken.
* **Threats Mitigated:**
* **Vulnerabilities in Plugins (Severity: Variable, potentially High):** Plugins, especially outdated ones, can have their own security vulnerabilities. Disabling them removes this attack vector.
* **Impact:**
* **Plugin Vulnerabilities:** Risk eliminated (if plugins are not needed).
* **Currently Implemented:** Implemented. PhantomJS is launched with `--load-plugins=false`.
* **Missing Implementation:** None.
Mitigation Strategy: Control Web Security Settings (with caveats)
Mitigation Strategy: Control Web Security Settings (with caveats)
* **Description:**
1. **`--web-security=true` (Default, but Verify):** Ensure that web security is enabled. This is usually the default, but it's good practice to explicitly include it in the command-line arguments: `--web-security=true`. This enables the Same-Origin Policy and other basic web security features. *However*, remember that PhantomJS's implementation is based on an old WebKit version, so it's not a perfect defense.
2. **`--ignore-ssl-errors=true` (AVOID):** *Do not* use this unless absolutely necessary. If you *must* use it (e.g., for testing with self-signed certificates), understand that it disables SSL/TLS certificate validation, making PhantomJS vulnerable to man-in-the-middle attacks. If used, ensure the network environment is tightly controlled.
3. **`--ssl-protocol=any` (AVOID):** It is better to specify secure protocol. If you *must* use it, understand the risks.
* **Threats Mitigated:**
* **Cross-Origin Attacks (Severity: Medium):** `--web-security=true` helps enforce the Same-Origin Policy, preventing some cross-origin attacks.
* **Man-in-the-Middle (MitM) Attacks (Severity: High):** *Avoiding* `--ignore-ssl-errors=true` is crucial for preventing MitM attacks.
* **Impact:**
* **Cross-Origin Attacks:** Risk reduced (but not eliminated, due to the outdated WebKit engine).
* **MitM Attacks:** Risk significantly reduced by *not* disabling SSL/TLS validation.
* **Currently Implemented:** Partially. `--web-security=true` is used. `--ignore-ssl-errors=true` is *not* used.
* **Missing Implementation:** None, regarding the recommended settings. The use of `--ssl-protocol=any` should be reviewed and, if possible, replaced with a more specific and secure protocol (e.g., `tlsv1.2` or `tlsv1.3`).