Lack of SSL Certificate Validation

The Webview class com.insecureshop.util.CustomWebViewClient contains the following code:

public final class CustomWebViewClient extends android.webkit.WebViewClient {
    public void onReceivedSslError(android.webkit.WebView view, android.webkit.SslErrorHandler handler, android.net.http.SslError error) {
        if (handler != null) {
            handler.proceed();
        }
    }
}

The code overrides the SSLError and proceeds with the attacker provided certificate. This makes the app vulnerable to MITM attacks.

This implies any HTTPS website loaded within webview can be intercepted by an attacker on the same network.

The attack scenario works as follows:

The easiest way to check such misconfiguration is to remove Burp CA cert from the mobile device and check if you can still intercept HTTPS traffic? If yes, then the application failed to validate SSL certificate.

You can also use the Nuclei template certificate-validation.yaml on a decompiled Android app to identify this misconfiguration.

echo /output_apktool/ | nuclei -t /file/android/certificate-validation.yaml