JAVA覆写Request过滤XSS跨站脚本攻击

时间：2022-05-01 07:32:24

注：本文非本人原著。

 

demo的地址：链接:http://pan.baidu.com/s/1miEmHMo 密码:k5ca

如何过滤Xss跨站脚本攻击，我想，Xss跨站脚本攻击令人为之头疼。为什么呢。

尤其是有富文本编辑器的产品。xss可能出现在http的head，不说别的，新浪多次出现。

xss可以出现在post数据的正文。图片的url。

于是各种Xss横行，如今Xss跨站脚本漏洞的流行程度甚至超过了当年的sql。

那么对于JAVA语言，如何防御呢。

笔者分享一个思路：所有的web项目，所有的参数都是request获得。

不管是json合适xml又或者post表单数据。甚至图片、文件等等都是如此。

那么，如果对request做个手脚。是不是就可以过滤xss了呢。

正是如此。

如下分享代码。网络上也有类似的过滤器，但不如笔者这份强悍。

  1 
  2 package com.blog.web.base.wrapper;
  3 
  4 import java.io.ByteArrayInputStream;
  5 import java.io.ByteArrayOutputStream;
  6 import java.io.IOException;
  7 import java.io.InputStream;
  8 import java.util.ArrayList;
  9 import java.util.Enumeration;
 10 import java.util.HashMap;
 11 import java.util.List;
 12 import java.util.Map;
 13 import java.util.regex.Pattern;
 14 
 15 import javax.servlet.ServletInputStream;
 16 import javax.servlet.http.HttpServletRequest;
 17 import javax.servlet.http.HttpServletRequestWrapper;
 18 
 19 /**
 20  * 覆写Request方法，过滤XSS恶意脚本
 21  *
 22  * @author WebSOS
 23  * @time 2015-06-09
 24  */
 25 public class XssHttpServletRequestWrapper extends HttpServletRequestWrapper {
 26 
 27 HttpServletRequest orgRequest = null;
 28 
 29 public XssHttpServletRequestWrapper(HttpServletRequest request) {
 30 super(request);
 31 orgRequest = request;
 32 }
 33 
 34 /**
 35  * 覆盖getParameter方法，将参数名和参数值都做xss过滤。
 36  */
 37 @Override
 38 public String getParameter(String name) {
 39 String value = super.getParameter(name);
 40 if (value != null) {
 41 value = xssEncode(value);
 42 }
 43 return value;
 44 }
 45 
 46 /**
 47  * 覆盖getHeader方法，将参数名和参数值都做xss过滤。 避免部分head操作引发的xss
 48  */
 49 @Override
 50 public String getHeader(String name) {
 51 
 52 String value = super.getHeader(name);
 53 if (value != null) {
 54 value = xssEncode(value);
 55 }
 56 return value;
 57 }
 58 
 59 /**
 60  * 覆盖getHeaderNames方法，避免穷举head参数名引发的xss
 61  */
 62 @Override
 63 public Enumeration<String> getHeaderNames() {
 64 
 65 Enumeration<String> headNames = super.getHeaderNames();
 66 String value = null;
 67 List<String> values = new ArrayList<String>();
 68 while (headNames.hasMoreElements()) {
 69 try {
 70 value = (String) headNames.nextElement();
 71 if (value == null) {
 72 continue;
 73 }
 74 value = xssEncode(value);
 75 values.add(value);
 76 } catch (Exception e) {
 77 e.printStackTrace();
 78 }
 79 }
 80 if (values.isEmpty()) {
 81 return null;
 82 }
 83 headNames = new XssEnumerator(0, values.size(), values);
 84 return headNames;
 85 }
 86 
 87 /**
 88  * 覆盖getParameterNames方法，避免穷举参数名引发的xss
 89  */
 90 @Override
 91 public Enumeration<String> getParameterNames() {
 92 Enumeration<String> paraNames = super.getParameterNames();
 93 if (paraNames == null) {
 94 return null;
 95 }
 96 String value = null;
 97 List<String> values = new ArrayList<String>();
 98 while (paraNames.hasMoreElements()) {
 99 try {
100 value = (String) paraNames.nextElement();
101 if (value == null) {
102 continue;
103 }
104 value = xssEncode(value);
105 values.add(value);
106 } catch (Exception e) {
107 e.printStackTrace();
108 }
109 }
110 if (values.isEmpty()) {
111 return null;
112 }
113 paraNames = new XssEnumerator(0, values.size(), values);
114 return paraNames;
115 }
116 
117 /**
118  * 覆盖getParameterMap方法，避免穷举参数名或值引发的xss
119  */
120 @Override
121 public Map<String, String[]> getParameterMap() {
122 Map<String, String[]> map = super.getParameterMap();
123 Map<String, String[]> paraMap = new HashMap<String, String[]>();
124 if (map == null) {
125 return null;
126 }
127 String[] values = null;
128 for (String key : map.keySet()) {
129 try {
130 values = map.get(key);
131 if (values != null) {
132 for (int i = 0; i < values.length; i++) {
133 try {
134 values[i] = xssEncode(values[i]);
135 } catch (Exception e) {
136 e.printStackTrace();
137 }
138 }
139 }
140 paraMap.put(xssEncode(key), values);
141 } catch (Exception e) {
142 e.printStackTrace();
143 }
144 }
145 return paraMap;
146 }
147 
148 /**
149  * 覆盖getInputStream方法，避免上传文件出现的xss或脚本代码
150  */
151 @Override
152 public ServletInputStream getInputStream() throws IOException {
153 XSSServletInputStream xssServletInputStream = new XSSServletInputStream();
154 ServletInputStream inputStream = orgRequest.getInputStream();
155 
156 ByteArrayOutputStream byteStream = new ByteArrayOutputStream();
157 try {
158 int ch;
159 while ((ch = inputStream.read()) != -1) {
160 byteStream.write(ch);
161 }
162 } finally {
163 inputStream.close();
164 }
165 xssServletInputStream.stream = new ByteArrayInputStream(xssEncode(
166 new String(byteStream.toByteArray(), "iso-8859-1")).getBytes(
167 "iso-8859-1"));
168 return xssServletInputStream;
169 }
170 
171 /**
172  * 将容易引起xss漏洞的字符清理掉
173  *
174  * @param s
175  * @return
176  */
177 private static String xssEncode(String value) {
178 if (value != null) {
179 /*
180  * value = value.replace("<", "&lt;"); value = value.replace(">",
181  * "&gt;");
182  */
183 // 如需开启富文本请撤销以下注释
184 
185 Pattern scriptPattern = Pattern.compile("<script>(.*?)</script>",
186 Pattern.CASE_INSENSITIVE);
187 value = scriptPattern.matcher(value).replaceAll("");
188 
189 scriptPattern = Pattern.compile("</script>",
190 Pattern.CASE_INSENSITIVE);
191 value = scriptPattern.matcher(value).replaceAll("");
192 
193 scriptPattern = Pattern.compile("<img.*?on.*?=.*?>",
194 Pattern.CASE_INSENSITIVE);
195 value = scriptPattern.matcher(value).replaceAll("");
196 
197 scriptPattern = Pattern.compile("<script(.*?)>",
198 Pattern.CASE_INSENSITIVE | Pattern.MULTILINE
199 | Pattern.DOTALL);
200 value = scriptPattern.matcher(value).replaceAll("");
201 
202 scriptPattern = Pattern.compile("eval\\((.*?)\\)",
203 Pattern.CASE_INSENSITIVE | Pattern.MULTILINE
204 | Pattern.DOTALL);
205 value = scriptPattern.matcher(value).replaceAll("");
206 
207 scriptPattern = Pattern.compile("e­xpression\\((.*?)\\)",
208 Pattern.CASE_INSENSITIVE | Pattern.MULTILINE
209 | Pattern.DOTALL);
210 value = scriptPattern.matcher(value).replaceAll("");
211 
212 scriptPattern = Pattern.compile("expression\\((.*?)\\)",
213 Pattern.CASE_INSENSITIVE | Pattern.MULTILINE
214 | Pattern.DOTALL);
215 value = scriptPattern.matcher(value).replaceAll("");
216 
217 scriptPattern = Pattern.compile("javascript:",
218 Pattern.CASE_INSENSITIVE);
219 value = scriptPattern.matcher(value).replaceAll("");
220 
221 scriptPattern = Pattern.compile("vbscript:",
222 Pattern.CASE_INSENSITIVE);
223 value = scriptPattern.matcher(value).replaceAll("");
224 
225 scriptPattern = Pattern.compile("onload(.*?)=",
226 Pattern.CASE_INSENSITIVE | Pattern.MULTILINE
227 | Pattern.DOTALL);
228 value = scriptPattern.matcher(value).replaceAll("");
229 
230 scriptPattern = Pattern.compile("<%.*?java.*?%>", Pattern.CASE_INSENSITIVE
231 | Pattern.MULTILINE | Pattern.DOTALL);
232 value = scriptPattern.matcher(value).replaceAll("");
233 
234 scriptPattern = Pattern.compile("<jsp:.*?>.*?</jsp:.*?>",
235 Pattern.CASE_INSENSITIVE | Pattern.MULTILINE
236 | Pattern.DOTALL);
237 value = scriptPattern.matcher(value).replaceAll("");
238 
239 scriptPattern = Pattern.compile("<meta.*?>",
240 Pattern.CASE_INSENSITIVE | Pattern.MULTILINE
241 | Pattern.DOTALL);
242 value = scriptPattern.matcher(value).replaceAll("");
243 
244 }
245 return value;
246 }
247 
248 /**
249  * 获取最原始的request
250  *
251  * @return
252  */
253 public HttpServletRequest getOrgRequest() {
254 
255 return orgRequest;
256 }
257 
258 /**
259  * 获取最原始的request的静态方法
260  *
261  * @return
262  */
263 public static HttpServletRequest getOrgRequest(HttpServletRequest req) {
264 if (req instanceof XssHttpServletRequestWrapper) {
265 return ((XssHttpServletRequestWrapper) req).getOrgRequest();
266 }
267 
268 return req;
269 }
270 
271 private class XSSServletInputStream extends ServletInputStream {
272 private InputStream stream;
273 
274 @Override
275 public int read() throws IOException {
276 return stream.read();
277 }
278 }
279 
280 private class XssEnumerator implements Enumeration<String> {
281 int count; // 计数器
282 int length; // 存储的数组的长度
283 List<String> dataArray; // 存储数据数组的引用
284 
285 XssEnumerator(int count, int length, List<String> dataArray) {
286 this.count = count;
287 this.length = length;
288 this.dataArray = dataArray;
289 
290 }
291 
292 public boolean hasMoreElements() {
293 return (count < length);
294 }
295 
296 public String nextElement() {
297 return dataArray.get(count++);
298 }
299 }
300 
301 public static void main(String[] args) {
302 Enumeration<String> paraNames = (Enumeration<String>) new ArrayList();
303 }
304 }
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