存储XSS问题与修复

安全漏洞描述

恶意攻击者往Web页面里插入恶意Script代码，当用户浏览该页时，嵌入其中Web里面的Script代码会被执行，进而窃取到管理员用户权限等。

风险等级：高

解决办法

1. 对网页端输入的特殊字符过滤
   建议过滤的关键字为：
   [1]’单引号
   [2]”双引号
   [3]/斜杠
   [4]反斜杠
   [5])括号
   [6];分号
   [7][中括号
   [8]<尖括号
   [9]>尖括号
   比如把<编码为<
2. 在cookie中加入httponly属性可以在一定程度上保护用户的cookie，减少出现XSS时损失。

一段简易的字符过滤程序

function htmlEncode(str){
    var s = "";
    if (str.length == 0) return "";
    s = str.replace(/&/g, "&");
    s = s.replace(//g, ">");
    s = s.replace(/ /g, " ");
    s = s.replace(/\'/g, "'");
    s = s.replace(/\"/g, """);
    return s;
}

3. 在服务端增加filter过滤
   通过自定义filter的方式拦截过滤请求

public class XssFilter implements Filter
{
    /**
     * 排除链接
     */
    public List<String> excludes = new ArrayList<>();

    @Override
    public void init(FilterConfig filterConfig) throws ServletException
    {
        String tempExcludes = filterConfig.getInitParameter("excludes");
        if (StringUtils.isNotEmpty(tempExcludes))
        {
            String[] url = tempExcludes.split(",");
            for (int i = 0; url != null && i < url.length; i++)
            {
                excludes.add(url[i]);
            }
        }
    }

    @Override
    public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain)
            throws IOException, ServletException
    {
        HttpServletRequest req = (HttpServletRequest) request;
        HttpServletResponse resp = (HttpServletResponse) response;
        if (handleExcludeURL(req, resp))
        {
            chain.doFilter(request, response);
            return;
        }
        XssHttpServletRequestWrapper xssRequest = new XssHttpServletRequestWrapper((HttpServletRequest) request);
        chain.doFilter(xssRequest, response);
    }

    private boolean handleExcludeURL(HttpServletRequest request, HttpServletResponse response)
    {
        String url = request.getServletPath();
        String method = request.getMethod();
        // GET DELETE 不过滤
        if (method == null || HttpMethod.GET.matches(method) || HttpMethod.DELETE.matches(method))
        {
            return true;
        }
        return StringUtils.matches(url, excludes);
    }
}

在wrapper里过滤参数

public class XssHttpServletRequestWrapper extends HttpServletRequestWrapper
{
    /**
     * @param request
     */
    public XssHttpServletRequestWrapper(HttpServletRequest request)
    {
        super(request);
    }

    @Override
    public String[] getParameterValues(String name)
    {
        String[] values = super.getParameterValues(name);
        if (values != null)
        {
            int length = values.length;
            String[] escapesValues = new String[length];
            for (int i = 0; i < length; i++)
            {
                // 防xss攻击和过滤前后空格
                escapesValues[i] = EscapeUtil.clean(values[i]).trim();
            }
            return escapesValues;
        }
        return super.getParameterValues(name);
    }

    @Override
    public ServletInputStream getInputStream() throws IOException
    {
        // 非json类型，直接返回
        if (!isJsonRequest())
        {
            return super.getInputStream();
        }

        // 为空，直接返回
        String json = IOUtils.toString(super.getInputStream(), "utf-8");
        if (StringUtils.isEmpty(json))
        {
            return super.getInputStream();
        }

        // xss过滤
        json = EscapeUtil.clean(json).trim();
        byte[] jsonBytes = json.getBytes("utf-8");
        final ByteArrayInputStream bis = new ByteArrayInputStream(jsonBytes);
        return new ServletInputStream()
        {
            @Override
            public boolean isFinished()
            {
                return true;
            }

            @Override
            public boolean isReady()
            {
                return true;
            }

            @Override
            public int available() throws IOException
            {
                return jsonBytes.length;
            }

            @Override
            public void setReadListener(ReadListener readListener)
            {
            }

            @Override
            public int read() throws IOException
            {
                return bis.read();
            }
        };
    }

    /**
     * 是否是Json请求
     * 
     * @param request
     */
    public boolean isJsonRequest()
    {
        String header = super.getHeader(HttpHeaders.CONTENT_TYPE);
        return StringUtils.startsWithIgnoreCase(header, MediaType.APPLICATION_JSON_VALUE);
    }
}

xssUtil

public class EscapeUtil
{
    public static final String RE_HTML_MARK = "(<[^<]*?>)|(<[\\s]*?/[^<]*?>)|(<[^<]*?/[\\s]*?>)";

    private static final char[][] TEXT = new char[64][];

    static
    {
        for (int i = 0; i < 64; i++)
        {
            TEXT[i] = new char[] { (char) i };
        }

        // special HTML characters
        TEXT['\''] = "&#039;".toCharArray(); // 单引号
        TEXT['"'] = "&#34;".toCharArray(); // 双引号
        TEXT['&'] = "&#38;".toCharArray(); // &符
        TEXT['<'] = "&#60;".toCharArray(); // 小于号
        TEXT['>'] = "&#62;".toCharArray(); // 大于号
    }

    /**
     * 转义文本中的HTML字符为安全的字符
     * 
     * @param text 被转义的文本
     * @return 转义后的文本
     */
    public static String escape(String text)
    {
        return encode(text);
    }

    /**
     * 还原被转义的HTML特殊字符
     * 
     * @param content 包含转义符的HTML内容
     * @return 转换后的字符串
     */
    public static String unescape(String content)
    {
        return decode(content);
    }

    /**
     * 清除所有HTML标签，但是不删除标签内的内容
     * 
     * @param content 文本
     * @return 清除标签后的文本
     */
    public static String clean(String content)
    {
        return new HTMLFilter().filter(content);
    }

    /**
     * Escape编码
     * 
     * @param text 被编码的文本
     * @return 编码后的字符
     */
    private static String encode(String text)
    {
        if (StringUtils.isEmpty(text))
        {
            return StringUtils.EMPTY;
        }

        final StringBuilder tmp = new StringBuilder(text.length() * 6);
        char c;
        for (int i = 0; i < text.length(); i++)
        {
            c = text.charAt(i);
            if (c < 256)
            {
                tmp.append("%");
                if (c < 16)
                {
                    tmp.append("0");
                }
                tmp.append(Integer.toString(c, 16));
            }
            else
            {
                tmp.append("%u");
                if (c <= 0xfff)
                {
                    // issue#I49JU8@Gitee
                    tmp.append("0");
                }
                tmp.append(Integer.toString(c, 16));
            }
        }
        return tmp.toString();
    }

    /**
     * Escape解码
     * 
     * @param content 被转义的内容
     * @return 解码后的字符串
     */
    public static String decode(String content)
    {
        if (StringUtils.isEmpty(content))
        {
            return content;
        }

        StringBuilder tmp = new StringBuilder(content.length());
        int lastPos = 0, pos = 0;
        char ch;
        while (lastPos < content.length())
        {
            pos = content.indexOf("%", lastPos);
            if (pos == lastPos)
            {
                if (content.charAt(pos + 1) == 'u')
                {
                    ch = (char) Integer.parseInt(content.substring(pos + 2, pos + 6), 16);
                    tmp.append(ch);
                    lastPos = pos + 6;
                }
                else
                {
                    ch = (char) Integer.parseInt(content.substring(pos + 1, pos + 3), 16);
                    tmp.append(ch);
                    lastPos = pos + 3;
                }
            }
            else
            {
                if (pos == -1)
                {
                    tmp.append(content.substring(lastPos));
                    lastPos = content.length();
                }
                else
                {
                    tmp.append(content.substring(lastPos, pos));
                    lastPos = pos;
                }
            }
        }
        return tmp.toString();
    }
}


public final class HTMLFilter
{
   /**
    * regex flag union representing /si modifiers in php
    **/
   private static final int REGEX_FLAGS_SI = Pattern.CASE_INSENSITIVE | Pattern.DOTALL;
   private static final Pattern P_COMMENTS = Pattern.compile("<!--(.*?)-->", Pattern.DOTALL);
   private static final Pattern P_COMMENT = Pattern.compile("^!--(.*)--$", REGEX_FLAGS_SI);
   private static final Pattern P_TAGS = Pattern.compile("<(.*?)>", Pattern.DOTALL);
   private static final Pattern P_END_TAG = Pattern.compile("^/([a-z0-9]+)", REGEX_FLAGS_SI);
   private static final Pattern P_START_TAG = Pattern.compile("^([a-z0-9]+)(.*?)(/?)$", REGEX_FLAGS_SI);
   private static final Pattern P_QUOTED_ATTRIBUTES = Pattern.compile("([a-z0-9]+)=([\"'])(.*?)\\2", REGEX_FLAGS_SI);
   private static final Pattern P_UNQUOTED_ATTRIBUTES = Pattern.compile("([a-z0-9]+)(=)([^\"\\s']+)", REGEX_FLAGS_SI);
   private static final Pattern P_PROTOCOL = Pattern.compile("^([^:]+):", REGEX_FLAGS_SI);
   private static final Pattern P_ENTITY = Pattern.compile("&#(\\d+);?");
   private static final Pattern P_ENTITY_UNICODE = Pattern.compile("&#x([0-9a-f]+);?");
   private static final Pattern P_ENCODE = Pattern.compile("%([0-9a-f]{2});?");
   private static final Pattern P_VALID_ENTITIES = Pattern.compile("&([^&;]*)(?=(;|&|$))");
   private static final Pattern P_VALID_QUOTES = Pattern.compile("(>|^)([^<]+?)(<|$)", Pattern.DOTALL);
   private static final Pattern P_END_ARROW = Pattern.compile("^>");
   private static final Pattern P_BODY_TO_END = Pattern.compile("<([^>]*?)(?=<|$)");
   private static final Pattern P_XML_CONTENT = Pattern.compile("(^|>)([^<]*?)(?=>)");
   private static final Pattern P_STRAY_LEFT_ARROW = Pattern.compile("<([^>]*?)(?=<|$)");
   private static final Pattern P_STRAY_RIGHT_ARROW = Pattern.compile("(^|>)([^<]*?)(?=>)");
   private static final Pattern P_AMP = Pattern.compile("&");
   private static final Pattern P_QUOTE = Pattern.compile("\"");
   private static final Pattern P_LEFT_ARROW = Pattern.compile("<");
   private static final Pattern P_RIGHT_ARROW = Pattern.compile(">");
   private static final Pattern P_BOTH_ARROWS = Pattern.compile("<>");

   // @xxx could grow large... maybe use sesat's ReferenceMap
   private static final ConcurrentMap<String, Pattern> P_REMOVE_PAIR_BLANKS = new ConcurrentHashMap<>();
   private static final ConcurrentMap<String, Pattern> P_REMOVE_SELF_BLANKS = new ConcurrentHashMap<>();

   /**
    * set of allowed html elements, along with allowed attributes for each element
    **/
   private final Map<String, List<String>> vAllowed;
   /**
    * counts of open tags for each (allowable) html element
    **/
   private final Map<String, Integer> vTagCounts = new HashMap<>();

   /**
    * html elements which must always be self-closing (e.g. "<img />")
    **/
   private final String[] vSelfClosingTags;
   /**
    * html elements which must always have separate opening and closing tags (e.g. "<b></b>")
    **/
   private final String[] vNeedClosingTags;
   /**
    * set of disallowed html elements
    **/
   private final String[] vDisallowed;
   /**
    * attributes which should be checked for valid protocols
    **/
   private final String[] vProtocolAtts;
   /**
    * allowed protocols
    **/
   private final String[] vAllowedProtocols;
   /**
    * tags which should be removed if they contain no content (e.g. "<b></b>" or "<b />")
    **/
   private final String[] vRemoveBlanks;
   /**
    * entities allowed within html markup
    **/
   private final String[] vAllowedEntities;
   /**
    * flag determining whether comments are allowed in input String.
    */
   private final boolean stripComment;
   private final boolean encodeQuotes;
   /**
    * flag determining whether to try to make tags when presented with "unbalanced" angle brackets (e.g. "<b text </b>"
    * becomes "<b> text </b>"). If set to false, unbalanced angle brackets will be html escaped.
    */
   private final boolean alwaysMakeTags;

   /**
    * Default constructor.
    */
   public HTMLFilter()
   {
      vAllowed = new HashMap<>();

      final ArrayList<String> a_atts = new ArrayList<>();
      a_atts.add("href");
      a_atts.add("target");
      vAllowed.put("a", a_atts);

      final ArrayList<String> img_atts = new ArrayList<>();
      img_atts.add("src");
      img_atts.add("width");
      img_atts.add("height");
      img_atts.add("alt");
      vAllowed.put("img", img_atts);

      final ArrayList<String> no_atts = new ArrayList<>();
      vAllowed.put("b", no_atts);
      vAllowed.put("strong", no_atts);
      vAllowed.put("i", no_atts);
      vAllowed.put("em", no_atts);

      vSelfClosingTags = new String[] { "img" };
      vNeedClosingTags = new String[] { "a", "b", "strong", "i", "em" };
      vDisallowed = new String[] {};
      vAllowedProtocols = new String[] { "http", "mailto", "https" }; // no ftp.
      vProtocolAtts = new String[] { "src", "href" };
      vRemoveBlanks = new String[] { "a", "b", "strong", "i", "em" };
      vAllowedEntities = new String[] { "amp", "gt", "lt", "quot" };
      stripComment = true;
      encodeQuotes = true;
      alwaysMakeTags = false;
   }

   /**
    * Map-parameter configurable constructor.
    *
    * @param conf map containing configuration. keys match field names.
    */
   @SuppressWarnings("unchecked")
   public HTMLFilter(final Map<String, Object> conf)
   {

      assert conf.containsKey("vAllowed") : "configuration requires vAllowed";
      assert conf.containsKey("vSelfClosingTags") : "configuration requires vSelfClosingTags";
      assert conf.containsKey("vNeedClosingTags") : "configuration requires vNeedClosingTags";
      assert conf.containsKey("vDisallowed") : "configuration requires vDisallowed";
      assert conf.containsKey("vAllowedProtocols") : "configuration requires vAllowedProtocols";
      assert conf.containsKey("vProtocolAtts") : "configuration requires vProtocolAtts";
      assert conf.containsKey("vRemoveBlanks") : "configuration requires vRemoveBlanks";
      assert conf.containsKey("vAllowedEntities") : "configuration requires vAllowedEntities";

      vAllowed = Collections.unmodifiableMap((HashMap<String, List<String>>) conf.get("vAllowed"));
      vSelfClosingTags = (String[]) conf.get("vSelfClosingTags");
      vNeedClosingTags = (String[]) conf.get("vNeedClosingTags");
      vDisallowed = (String[]) conf.get("vDisallowed");
      vAllowedProtocols = (String[]) conf.get("vAllowedProtocols");
      vProtocolAtts = (String[]) conf.get("vProtocolAtts");
      vRemoveBlanks = (String[]) conf.get("vRemoveBlanks");
      vAllowedEntities = (String[]) conf.get("vAllowedEntities");
      stripComment = conf.containsKey("stripComment") ? (Boolean) conf.get("stripComment") : true;
      encodeQuotes = conf.containsKey("encodeQuotes") ? (Boolean) conf.get("encodeQuotes") : true;
      alwaysMakeTags = conf.containsKey("alwaysMakeTags") ? (Boolean) conf.get("alwaysMakeTags") : true;
   }

   private void reset()
   {
      vTagCounts.clear();
   }

   // ---------------------------------------------------------------
   // my versions of some PHP library functions
   public static String chr(final int decimal)
   {
      return String.valueOf((char) decimal);
   }

   public static String htmlSpecialChars(final String s)
   {
      String result = s;
      result = regexReplace(P_AMP, "&amp;", result);
      result = regexReplace(P_QUOTE, "&quot;", result);
      result = regexReplace(P_LEFT_ARROW, "&lt;", result);
      result = regexReplace(P_RIGHT_ARROW, "&gt;", result);
      return result;
   }

   // ---------------------------------------------------------------

   /**
    * given a user submitted input String, filter out any invalid or restricted html.
    *
    * @param input text (i.e. submitted by a user) than may contain html
    * @return "clean" version of input, with only valid, whitelisted html elements allowed
    */
   public String filter(final String input)
   {
      reset();
      String s = input;

      s = escapeComments(s);

      s = balanceHTML(s);

      s = checkTags(s);

      s = processRemoveBlanks(s);

      // s = validateEntities(s);

      return s;
   }

   public boolean isAlwaysMakeTags()
   {
      return alwaysMakeTags;
   }

   public boolean isStripComments()
   {
      return stripComment;
   }

   private String escapeComments(final String s)
   {
      final Matcher m = P_COMMENTS.matcher(s);
      final StringBuffer buf = new StringBuffer();
      if (m.find())
      {
         final String match = m.group(1); // (.*?)
         m.appendReplacement(buf, Matcher.quoteReplacement("<!--" + htmlSpecialChars(match) + "-->"));
      }
      m.appendTail(buf);

      return buf.toString();
   }

   private String balanceHTML(String s)
   {
      if (alwaysMakeTags)
      {
         //
         // try and form html
         //
         s = regexReplace(P_END_ARROW, "", s);
         // 不追加结束标签
         s = regexReplace(P_BODY_TO_END, "<$1>", s);
         s = regexReplace(P_XML_CONTENT, "$1<$2", s);

      }
      else
      {
         //
         // escape stray brackets
         //
         s = regexReplace(P_STRAY_LEFT_ARROW, "&lt;$1", s);
         s = regexReplace(P_STRAY_RIGHT_ARROW, "$1$2&gt;<", s);

         //
         // the last regexp causes '<>' entities to appear
         // (we need to do a lookahead assertion so that the last bracket can
         // be used in the next pass of the regexp)
         //
         s = regexReplace(P_BOTH_ARROWS, "", s);
      }

      return s;
   }

   private String checkTags(String s)
   {
      Matcher m = P_TAGS.matcher(s);

      final StringBuffer buf = new StringBuffer();
      while (m.find())
      {
         String replaceStr = m.group(1);
         replaceStr = processTag(replaceStr);
         m.appendReplacement(buf, Matcher.quoteReplacement(replaceStr));
      }
      m.appendTail(buf);

      // these get tallied in processTag
      // (remember to reset before subsequent calls to filter method)
      final StringBuilder sBuilder = new StringBuilder(buf.toString());
      for (String key : vTagCounts.keySet())
      {
         for (int ii = 0; ii < vTagCounts.get(key); ii++)
         {
            sBuilder.append("</").append(key).append(">");
         }
      }
      s = sBuilder.toString();

      return s;
   }

   private String processRemoveBlanks(final String s)
   {
      String result = s;
      for (String tag : vRemoveBlanks)
      {
         if (!P_REMOVE_PAIR_BLANKS.containsKey(tag))
         {
            P_REMOVE_PAIR_BLANKS.putIfAbsent(tag, Pattern.compile("<" + tag + "(\\s[^>]*)?></" + tag + ">"));
         }
         result = regexReplace(P_REMOVE_PAIR_BLANKS.get(tag), "", result);
         if (!P_REMOVE_SELF_BLANKS.containsKey(tag))
         {
            P_REMOVE_SELF_BLANKS.putIfAbsent(tag, Pattern.compile("<" + tag + "(\\s[^>]*)?/>"));
         }
         result = regexReplace(P_REMOVE_SELF_BLANKS.get(tag), "", result);
      }

      return result;
   }

   private static String regexReplace(final Pattern regex_pattern, final String replacement, final String s)
   {
      Matcher m = regex_pattern.matcher(s);
      return m.replaceAll(replacement);
   }

   private String processTag(final String s)
   {
      // ending tags
      Matcher m = P_END_TAG.matcher(s);
      if (m.find())
      {
         final String name = m.group(1).toLowerCase();
         if (allowed(name))
         {
            if (!inArray(name, vSelfClosingTags))
            {
               if (vTagCounts.containsKey(name))
               {
                  vTagCounts.put(name, vTagCounts.get(name) - 1);
                  return "</" + name + ">";
               }
            }
         }
      }

      // starting tags
      m = P_START_TAG.matcher(s);
      if (m.find())
      {
         final String name = m.group(1).toLowerCase();
         final String body = m.group(2);
         String ending = m.group(3);

         // debug( "in a starting tag, name='" + name + "'; body='" + body + "'; ending='" + ending + "'" );
         if (allowed(name))
         {
            final StringBuilder params = new StringBuilder();

            final Matcher m2 = P_QUOTED_ATTRIBUTES.matcher(body);
            final Matcher m3 = P_UNQUOTED_ATTRIBUTES.matcher(body);
            final List<String> paramNames = new ArrayList<>();
            final List<String> paramValues = new ArrayList<>();
            while (m2.find())
            {
               paramNames.add(m2.group(1)); // ([a-z0-9]+)
               paramValues.add(m2.group(3)); // (.*?)
            }
            while (m3.find())
            {
               paramNames.add(m3.group(1)); // ([a-z0-9]+)
               paramValues.add(m3.group(3)); // ([^\"\\s']+)
            }

            String paramName, paramValue;
            for (int ii = 0; ii < paramNames.size(); ii++)
            {
               paramName = paramNames.get(ii).toLowerCase();
               paramValue = paramValues.get(ii);

               // debug( "paramName='" + paramName + "'" );
               // debug( "paramValue='" + paramValue + "'" );
               // debug( "allowed? " + vAllowed.get( name ).contains( paramName ) );

               if (allowedAttribute(name, paramName))
               {
                  if (inArray(paramName, vProtocolAtts))
                  {
                     paramValue = processParamProtocol(paramValue);
                  }
                  params.append(' ').append(paramName).append("=\\\"").append(paramValue).append("\\\"");
               }
            }

            if (inArray(name, vSelfClosingTags))
            {
               ending = " /";
            }

            if (inArray(name, vNeedClosingTags))
            {
               ending = "";
            }

            if (ending == null || ending.length() < 1)
            {
               if (vTagCounts.containsKey(name))
               {
                  vTagCounts.put(name, vTagCounts.get(name) + 1);
               }
               else
               {
                  vTagCounts.put(name, 1);
               }
            }
            else
            {
               ending = " /";
            }
            return "<" + name + params + ending + ">";
         }
         else
         {
            return "";
         }
      }

      // comments
      m = P_COMMENT.matcher(s);
      if (!stripComment && m.find())
      {
         return "<" + m.group() + ">";
      }

      return "";
   }

   private String processParamProtocol(String s)
   {
      s = decodeEntities(s);
      final Matcher m = P_PROTOCOL.matcher(s);
      if (m.find())
      {
         final String protocol = m.group(1);
         if (!inArray(protocol, vAllowedProtocols))
         {
            // bad protocol, turn into local anchor link instead
            s = "#" + s.substring(protocol.length() + 1);
            if (s.startsWith("#//"))
            {
               s = "#" + s.substring(3);
            }
         }
      }

      return s;
   }

   private String decodeEntities(String s)
   {
      StringBuffer buf = new StringBuffer();

      Matcher m = P_ENTITY.matcher(s);
      while (m.find())
      {
         final String match = m.group(1);
         final int decimal = Integer.decode(match).intValue();
         m.appendReplacement(buf, Matcher.quoteReplacement(chr(decimal)));
      }
      m.appendTail(buf);
      s = buf.toString();

      buf = new StringBuffer();
      m = P_ENTITY_UNICODE.matcher(s);
      while (m.find())
      {
         final String match = m.group(1);
         final int decimal = Integer.valueOf(match, 16).intValue();
         m.appendReplacement(buf, Matcher.quoteReplacement(chr(decimal)));
      }
      m.appendTail(buf);
      s = buf.toString();

      buf = new StringBuffer();
      m = P_ENCODE.matcher(s);
      while (m.find())
      {
         final String match = m.group(1);
         final int decimal = Integer.valueOf(match, 16).intValue();
         m.appendReplacement(buf, Matcher.quoteReplacement(chr(decimal)));
      }
      m.appendTail(buf);
      s = buf.toString();

      s = validateEntities(s);
      return s;
   }

   private String validateEntities(final String s)
   {
      StringBuffer buf = new StringBuffer();

      // validate entities throughout the string
      Matcher m = P_VALID_ENTITIES.matcher(s);
      while (m.find())
      {
         final String one = m.group(1); // ([^&;]*)
         final String two = m.group(2); // (?=(;|&|$))
         m.appendReplacement(buf, Matcher.quoteReplacement(checkEntity(one, two)));
      }
      m.appendTail(buf);

      return encodeQuotes(buf.toString());
   }

   private String encodeQuotes(final String s)
   {
      if (encodeQuotes)
      {
         StringBuffer buf = new StringBuffer();
         Matcher m = P_VALID_QUOTES.matcher(s);
         while (m.find())
         {
            final String one = m.group(1); // (>|^)
            final String two = m.group(2); // ([^<]+?)
            final String three = m.group(3); // (<|$)
            // 不替换双引号为&quot;，防止json格式无效 regexReplace(P_QUOTE, "&quot;", two)
            m.appendReplacement(buf, Matcher.quoteReplacement(one + two + three));
         }
         m.appendTail(buf);
         return buf.toString();
      }
      else
      {
         return s;
      }
   }

   private String checkEntity(final String preamble, final String term)
   {

      return ";".equals(term) && isValidEntity(preamble) ? '&' + preamble : "&amp;" + preamble;
   }

   private boolean isValidEntity(final String entity)
   {
      return inArray(entity, vAllowedEntities);
   }

   private static boolean inArray(final String s, final String[] array)
   {
      for (String item : array)
      {
         if (item != null && item.equals(s))
         {
            return true;
         }
      }
      return false;
   }

   private boolean allowed(final String name)
   {
      return (vAllowed.isEmpty() || vAllowed.containsKey(name)) && !inArray(name, vDisallowed);
   }

   private boolean allowedAttribute(final String name, final String paramName)
   {
      return allowed(name) && (vAllowed.isEmpty() || vAllowed.get(name).contains(paramName));
   }
}

前后端组合使用，可解决xss问题

安全无小事！！！

存储型XSS漏洞解决方案