com.codedx.burp.security.InvalidCertificateDialogStrategy.java Source code

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Here is the source code for com.codedx.burp.security.InvalidCertificateDialogStrategy.java

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/*
 * Copyright (C) 2016 Code Dx, Inc. - http://www.codedx.com
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.codedx.burp.security;

import java.awt.Font;
import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;
import java.awt.Insets;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import java.security.cert.Certificate;
import java.security.cert.CertificateEncodingException;
import java.security.cert.CertificateException;
import java.security.cert.X509Certificate;
import java.util.Formatter;
import java.util.StringTokenizer;

import javax.net.ssl.HostnameVerifier;
import javax.net.ssl.SSLException;
import javax.swing.JLabel;
import javax.swing.JOptionPane;
import javax.swing.JPanel;

import org.apache.http.conn.ssl.DefaultHostnameVerifier;

import burp.BurpExtender;

/**
 * An InvalidCertificateStrategy implementation that opens a dialog, prompting
 * the user for their choice of action.
 */
public class InvalidCertificateDialogStrategy implements InvalidCertificateStrategy {

    private final HostnameVerifier defaultHostVerifier;
    private final String host;
    private BurpExtender burpExtender;

    private final static String dialogTitle = "Untrusted Digital Certificate";
    private final static String[] dialogButtons = { "Reject", "Accept Temporarily", "Accept Permanently" };

    public InvalidCertificateDialogStrategy(HostnameVerifier defaultHostVerifier, String host, BurpExtender be) {
        this.defaultHostVerifier = defaultHostVerifier;
        this.host = host;
        this.burpExtender = be;
    }

    @Override
    public CertificateAcceptance checkAcceptance(Certificate genericCert, CertificateException certError) {
        if (genericCert instanceof X509Certificate && defaultHostVerifier instanceof DefaultHostnameVerifier) {
            X509Certificate cert = (X509Certificate) genericCert;
            DefaultHostnameVerifier verifier = (DefaultHostnameVerifier) defaultHostVerifier;

            JPanel message = new JPanel(new GridBagLayout());
            GridBagConstraints gbc = new GridBagConstraints();
            gbc.gridwidth = 2;
            gbc.insets = new Insets(0, 0, 10, 0);
            gbc.anchor = GridBagConstraints.WEST;
            message.add(
                    new JLabel("Unable to establish a secure connection because the certificate is not trusted"),
                    gbc);

            gbc = new GridBagConstraints();
            gbc.gridy = 2;
            gbc.insets = new Insets(2, 0, 2, 0);
            gbc.anchor = GridBagConstraints.WEST;

            JLabel issuer = new JLabel("Issuer: ");
            Font defaultFont = issuer.getFont();
            Font bold = new Font(defaultFont.getName(), Font.BOLD, defaultFont.getSize());
            issuer.setFont(bold);

            message.add(issuer, gbc);
            gbc.gridx = 1;
            message.add(new JLabel(cert.getIssuerDN().toString()), gbc);

            try {
                JLabel fingerprint = new JLabel("Thumbprint: ");
                fingerprint.setFont(bold);
                gbc.gridx = 0;
                gbc.gridy += 1;
                message.add(fingerprint, gbc);

                gbc.gridx = 1;
                message.add(new JLabel(toHexString(getSHA1(cert.getEncoded()), " ")), gbc);
            } catch (CertificateEncodingException e) {
                // this shouldn't actually ever happen
            }

            try {
                verifier.verify(host, cert);
            } catch (SSLException e) {
                String cn = getCN(cert);

                JLabel mismatch = new JLabel("Host Mismatch: ");
                mismatch.setFont(bold);
                gbc.gridx = 0;
                gbc.gridy += 1;
                message.add(mismatch, gbc);

                String msg;
                if (cn != null) {
                    msg = String.format("Expected '%s', but the certificate is for '%s'.", host, cn);
                } else {
                    msg = e.getMessage();
                }

                gbc.gridx = 1;
                message.add(new JLabel(msg), gbc);
            }

            // Open the dialog, and return its result
            int choice = JOptionPane.showOptionDialog(burpExtender.getUiComponent(), message, dialogTitle,
                    JOptionPane.YES_NO_CANCEL_OPTION, JOptionPane.PLAIN_MESSAGE, null, dialogButtons, null);
            switch (choice) {
            case (0):
                return CertificateAcceptance.REJECT;
            case (1):
                return CertificateAcceptance.ACCEPT_TEMPORARILY;
            case (2):
                return CertificateAcceptance.ACCEPT_PERMANENTLY;
            }
        }
        return CertificateAcceptance.REJECT;
    }

    public static byte[] getSHA1(byte[] input) {
        try {
            MessageDigest md = MessageDigest.getInstance("SHA-1");
            md.reset();
            return md.digest(input);
        } catch (NoSuchAlgorithmException e) {
            throw new RuntimeException(e);
        }
    }

    public static String toHexString(byte[] bytes, String sep) {
        Formatter f = new Formatter();
        for (int i = 0; i < bytes.length; i++) {
            f.format("%02x", bytes[i]);
            if (i < bytes.length - 1) {
                f.format(sep);
            }
        }
        String result = f.toString();
        f.close();
        return result;
    }

    private static String getCN(X509Certificate cert) {
        String principal = cert.getSubjectX500Principal().toString();
        StringTokenizer tokenizer = new StringTokenizer(principal, ",");
        while (tokenizer.hasMoreTokens()) {
            String token = tokenizer.nextToken();
            int i = token.indexOf("CN=");
            if (i >= 0) {
                return token.substring(i + 3);
            }
        }
        return null;
    }
}