ContentSniffing.java

/*
 *Copyright 2014 Google Inc. All rights reserved.
 *
 * 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.google.testing.security.firingrange.tests.reflected;

import com.google.common.annotations.VisibleForTesting;
import com.google.common.base.Splitter;
import com.google.common.base.Strings;
import com.google.testing.security.firingrange.utils.Responses;
import com.google.testing.security.firingrange.utils.Templates;

import java.io.IOException;

import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

/**
 * Handles reflected XSS on JSON via content sniffing. Note that this method reacts
 * to a callback parameter which is not directly linked from the HTML pages. Scanners
 * should be able to identify it themselves.
 */
public class ContentSniffing extends HttpServlet {
  @VisibleForTesting
  static final String ECHOED_PARAM = "q";

  @Override
  public void doGet(HttpServletRequest request, HttpServletResponse response) throws IOException {
    String echoedParam = Strings.nullToEmpty(request.getParameter(ECHOED_PARAM));
    echoedParam = echoedParam.replace("\"", "\\\"");
    String template = Templates.getTemplate("json.tmpl", getClass());

    String testType = Splitter.on('/').splitToList(request.getPathInfo()).get(1);
    String contentType;
    switch (testType) {
      case "json":
        contentType = "application/json";
        break;
      case "plaintext":
        contentType = "text/plain";
        break;
      default:
        throw new IllegalArgumentException();
    }
    Responses.sendXssed(response, Templates.replacePayload(template, echoedParam), contentType);
  }
}