Cross-site scripting tool (cross-site scripting), in order not to be confused with the abbreviation of cascading style sheets (CSS), so the cross-site scripting attack is abbreviated as XSS. A malicious attacker inserts malicious scriptScript code into a web page. When a user browses the page, the script code embedded in the web page will be executed, thereby achieving the purpose of maliciously attacking the user. The simple prevention of preventing XSS attacks is to remove some sensitive script commands from some parameters in the Request request.
It was originally intended to be implemented through the HandlerInterceptor mechanism of springMVC. By obtaining the request and then modifying the parameters in the request, although the value has been modified, the value obtained in the Controller has not been modified. No way is to filter to complete. Simply put, it is to create a new httpRequest class XsslHttpServletRequestWrapper, and then rewrite some get methods (XSS judgment and prevention of parameters when getting parameters).
@WebFilter(filterName="xssMyfilter",urlPatterns="/*")
public class MyXssFilter implements Filter{
@Override
public void init(FilterConfig filterConfig) throws ServletException {
}
@Override
public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain)
throws IOException, ServletException {
XsslHttpServletRequestWrapper xssRequest = new XsslHttpServletRequestWrapper((HttpServletRequest)request);
chain.doFilter(xssRequest , response);
}
@Override
public void destroy() {
}
}
The filtering of XSS code is implemented in XsslHttpServletRequestWrapper, mainly by overriding the methods of getParameter, getParameterValues, and getHeader, and then performing XSS processing on the obtained value.
public class XsslHttpServletRequestWrapper extends HttpServletRequestWrapper {
HttpServletRequest xssRequest = null;
public XsslHttpServletRequestWrapper(HttpServletRequest request) {
super(request);
xssRequest = request;
}
@Override
public String getParameter(String name) {
String value = super.getParameter(replaceXSS(name));
if (value != null) {
value = replaceXSS(value);
}
return value;
}
@Override
public String[] getParameterValues(String name) {
String[] values = super.getParameterValues(replaceXSS(name));
if(values != null && values.length > 0){
for(int i =0; i< values.length ;i++){
values[i] = replaceXSS(values[i]);
}
}
return values;
}
@Override
public String getHeader(String name) {
String value = super.getHeader(replaceXSS(name));
if (value != null) {
value = replaceXSS(value);
}
return value;
}
/**
* 去除待带script、src的语句，转义替换后的value值
*/
public static String replaceXSS(String value) {
if (value != null) {
try{
value = value.replace("+","%2B"); //'+' replace to '%2B'
value = URLDecoder.decode(value, "utf-8");
}catch(UnsupportedEncodingException e){
}catch(IllegalArgumentException e){
}
// Avoid null characters
value = value.replaceAll("\0", "");
// Avoid anything between script tags
Pattern scriptPattern = Pattern.compile("<script>(.*?)</script>", Pattern.CASE_INSENSITIVE);
value = scriptPattern.matcher(value).replaceAll("");
// Avoid anything in a src='...' type of expression
scriptPattern = Pattern.compile("src[\r\n]*=[\r\n]*\\\'(.*?)\\\'", Pattern.CASE_INSENSITIVE | Pattern.MULTILINE | Pattern.DOTALL);
value = scriptPattern.matcher(value).replaceAll("");
scriptPattern = Pattern.compile("src[\r\n]*=[\r\n]*\\\"(.*?)\\\"", Pattern.CASE_INSENSITIVE | Pattern.MULTILINE | Pattern.DOTALL);
value = scriptPattern.matcher(value).replaceAll("");
// Remove any lonesome </script> tag
scriptPattern = Pattern.compile("</script>", Pattern.CASE_INSENSITIVE);
value = scriptPattern.matcher(value).replaceAll("");
// Remove any lonesome <script ...> tag
scriptPattern = Pattern.compile("<script(.*?)>", Pattern.CASE_INSENSITIVE | Pattern.MULTILINE | Pattern.DOTALL);
value = scriptPattern.matcher(value).replaceAll("");
// Avoid eval(...) expressions
scriptPattern = Pattern.compile("eval\\((.*?)\\)", Pattern.CASE_INSENSITIVE | Pattern.MULTILINE | Pattern.DOTALL);
value = scriptPattern.matcher(value).replaceAll("");
// Avoid expression(...) expressions
scriptPattern = Pattern.compile("expression\\((.*?)\\)", Pattern.CASE_INSENSITIVE | Pattern.MULTILINE | Pattern.DOTALL);
value = scriptPattern.matcher(value).replaceAll("");
// Avoid javascript:... expressions
scriptPattern = Pattern.compile("javascript:", Pattern.CASE_INSENSITIVE);
value = scriptPattern.matcher(value).replaceAll("");
// Avoid alert:... expressions
scriptPattern = Pattern.compile("alert", Pattern.CASE_INSENSITIVE);
value = scriptPattern.matcher(value).replaceAll("");
// Avoid onload= expressions
scriptPattern = Pattern.compile("onload(.*?)=", Pattern.CASE_INSENSITIVE | Pattern.MULTILINE | Pattern.DOTALL);
value = scriptPattern.matcher(value).replaceAll("");
scriptPattern = Pattern.compile("vbscript[\r\n| | ]*:[\r\n| | ]*", Pattern.CASE_INSENSITIVE);
value = scriptPattern.matcher(value).replaceAll("");
}
return filter(value);
}
/**
* 过滤特殊字符
*/
public static String filter(String value) {
if (value == null) {
return null;
}
StringBuffer result = new StringBuffer(value.length());
for (int i=0; i<value.length(); ++i) {
switch (value.charAt(i)) {
case '<':
result.append("<");
break;
case '>':
result.append(">");
break;
case '"':
result.append(""");
break;
case '\'':
result.append("'");
break;
case '%':
result.append("%");
break;
case ';':
result.append(";");
break;
case '(':
result.append("(");
break;
case ')':
result.append(")");
break;
case '&':
result.append("&");
break;
case '+':
result.append("+");
break;
default:
result.append(value.charAt(i));
break;
}
}
return result.toString();
}
}
Reprinted: https://blog.csdn.net/qq924862077/article/details/62053577