防XSS攻击和SQL注入手段

       XSS攻击全称跨站脚本攻击，是为不和层叠样式表(Cascading Style Sheets, CSS)的缩写混淆，故将跨站脚本攻击缩写为XSS，XSS是一种在web应用中的计算机安全漏洞，它允许恶意web用户将代码植入到提供给其它用户使用的页面中。XSS漏洞和著名的SQL注入漏洞一样，都是利用了Web页面的编写不完善，所以每一个漏洞所利用和针对的弱点都不尽相同。

       这里我采用过滤关键字的方法一定程度上的防御这些攻击。

第一步：在web.xml内配置

第二步：编写类

第一个类：

/*
* 文 件 名: XssFilter.java
* 版 权: 深圳钱眼金融控股有限公司
* 描 述: <描述>
* 修 改 人: suwei
* 修改时间: 2017年9月1日
*/
package com.research.filter;

import java.io.IOException;

import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.http.HttpServletRequest;

/**
* 过滤用户提交的参数，防止XSS攻击
* <功能详细描述>
* 
*/
public class XssFilter implements Filter
{
public void init(FilterConfig config)
throws ServletException
{
}

public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain)
throws IOException, ServletException
{
HttpServletRequest req = (HttpServletRequest)request;
/* Adminuser user = (Adminuser)req.getSession().getAttribute(Constant.ADMINLOGIN_SUCCESS);
if (user != null)
{
//如果是后台请求则不需要经过XSS请求过滤
chain.doFilter(request, response);
}
else
{*/
//构造一个XSS请求装饰器
XssHttpServletRequestWrapper xssRequest = new XssHttpServletRequestWrapper((HttpServletRequest)request);
chain.doFilter(xssRequest, response);
/* }*/
}

public void destroy()
{
}
}

第二个文件：

/*
* 文 件 名: XssHttpServletRequestWrapper.java
* 版 权: 深圳钱眼金融控股有限公司
* 描 述: <描述>
*/
package com.research.filter;

import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;
import java.util.regex.Pattern;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletRequestWrapper;

/**
* XSS请求装饰器，完成具体的请求过滤操作
* <功能详细描述>
* 
* @author sun
* @version [版本号, 2018年2月25日]
*/
public class XssHttpServletRequestWrapper extends HttpServletRequestWrapper
{
HttpServletRequest orgRequest = null;

// SQL关键字
/*public static final String[] SQL_KEYS =
{"%", "select", "insert", "delete", "from", "count\\(", "drop table", "update", "truncate", "asc\\(", "mid\\(",
"char\\(", "xp_cmdshell", "exec", "master", "netlocalgroup administrators", "net user", "or", "and"};*/

public static final String SQL_KEYS =
"exec |execute |insert |select |delete |update |drop |chr |mid |master |truncate |char |declare |sitename |net user |xp_cmdshell|like '|create |drop |table |from |grant |group_concat|column_name|information_schema.columns|table_schema|union |where |or |"
+ "EXEC |EXECUTE |INSERT |SELECT |DELETE |UPDATE |DROP |CHR |MID |MASTER |TRUNCATE |CHAR |DECLARE |SITENAME |NET USER|XP_CMDSHELL|LIKE '|CREATE |DROP |TABLE |FROM |GRANT |GROUP_CONCAT|COLUMN_NAME|INFORMATION_SCHEMA.COLUMNS|TABLE_SCHEMA|UNION |WHERE |COUNT |OR ";

public XssHttpServletRequestWrapper(HttpServletRequest request)
{
super(request);
orgRequest = request;
}

/**
* 覆盖getParameter方法，将参数名和参数值都做xss过滤。<br/>
*/
@Override
public String getParameter(String name)
{
String value = super.getParameter(xssEncode(name));
if (value != null)
{
value = xssEncode(value);
}
return value;
}

@Override
public String[] getParameterValues(String name)
{
// 返回值之前 先进行过滤
String[] values = super.getParameterValues(name);
if (values != null)
{
for (int i = 0; i < values.length; i++)
{
values[i] = xssEncode(values[i]);
}
}
return values;
}

@Override
public Map<String, String[]> getParameterMap()
{
HashMap<String, String[]> paramMap = (HashMap<String, String[]>)super.getParameterMap();
paramMap = (HashMap<String, String[]>)paramMap.clone();

for (Iterator iterator = paramMap.entrySet().iterator(); iterator.hasNext();)
{
Map.Entry<String, String[]> entry = (Map.Entry<String, String[]>)iterator.next();
String[] values = entry.getValue();
for (int i = 0; i < values.length; i++)
{
if (values[i] instanceof String)
{
values[i] = xssEncode(values[i]);
}
}
entry.setValue(values);
}
return paramMap;
}

/**
* 覆盖getHeader方法，将参数名和参数值都做xss过滤。<br/>
* 如果需要获得原始的值，则通过super.getHeaders(name)来获取<br/>
* getHeaderNames 也可能需要覆盖
*/
/* @Override
public String getHeader(String name)
{
String value = super.getHeader(xssEncode(name));
if (value != null)
{
value = xssEncode(value);
}
return value;
}*/

/**
* 将容易引起xss漏洞的半角字符直接替换成全角字符
*
* @param s
* @return
*/
private static String xssEncode(String s)
{
if (s == null || s.isEmpty())
{
return s;
}
else
{
s = stripXSSAndSql(s);
}
StringBuilder sb = new StringBuilder(s.length() + 16);
for (int i = 0; i < s.length(); i++)
{
char c = s.charAt(i);
switch (c)
{
case '>':
sb.append('＞');// 全角大于号
break;
case '<':
sb.append('＜');// 全角小于号
break;
case '\'':
sb.append('‘');// 全角单引号
break;
case '\"':
sb.append('“');// 全角双引号
break;
case '&':
sb.append('＆');// 全角
break;
case '\\':
sb.append('＼');// 全角斜线
break;
case '#':
sb.append('＃');// 全角井号
break;
case '%': // < 字符的 URL 编码形式表示的 ASCII 字符（十六进制格式） 是: %3c
processUrlEncoder(sb, s, i);
break;
default:
sb.append(c);
break;
}
}
return s;
}

public static void processUrlEncoder(StringBuilder sb, String s, int index)
{
if (s.length() >= index + 2)
{
if (s.charAt(index + 1) == '3' && (s.charAt(index + 2) == 'c' || s.charAt(index + 2) == 'C'))
{ // %3c, %3C
sb.append('＜');
return;
}
if (s.charAt(index + 1) == '6' && s.charAt(index + 2) == '0')
{ // %3c (0x3c=60)
sb.append('＜');
return;
}
if (s.charAt(index + 1) == '3' && (s.charAt(index + 2) == 'e' || s.charAt(index + 2) == 'E'))
{ // %3e, %3E
sb.append('＞');
return;
}
if (s.charAt(index + 1) == '6' && s.charAt(index + 2) == '2')
{ // %3e (0x3e=62)
sb.append('＞');
return;
}
}
sb.append(s.charAt(index));
}

/**
* 获取最原始的request
*
* @return
*/
public HttpServletRequest getOrgRequest()
{
return orgRequest;
}

/**
* 获取最原始的request的静态方法
*
* @return
*/
public static HttpServletRequest getOrgRequest(HttpServletRequest req)
{
if (req instanceof XssHttpServletRequestWrapper)
{
return ((XssHttpServletRequestWrapper)req).getOrgRequest();
}
return req;
}

/** 
* 
* 防止xss跨脚本攻击（替换，根据实际情况调整） 
*/
public static String stripXSSAndSql(String value)
{
if (value != null)
{
// Avoid anything between script tags 
Pattern scriptPattern = Pattern.compile(
"<[\r\n| | ]*script[\r\n| | ]*>(.*?)</[\r\n| | ]*script[\r\n| | ]*>", Pattern.CASE_INSENSITIVE);
value = scriptPattern.matcher(value).replaceAll("");

// Avoid anything in a src="http://www.yihaomen.com/article/java/..." type of e-xpression 
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("</[\r\n| | ]*script[\r\n| | ]*>", Pattern.CASE_INSENSITIVE);
value = scriptPattern.matcher(value).replaceAll("");

// Remove any lonesome <script ...> tag 
scriptPattern = Pattern.compile("<[\r\n| | ]*script(.*?)>",
Pattern.CASE_INSENSITIVE | Pattern.MULTILINE | Pattern.DOTALL);
value = scriptPattern.matcher(value).replaceAll("");

// Remove any lonesome <img ...> tag 
scriptPattern =
Pattern.compile("<[\r\n| | ]*img(.*?)>", Pattern.CASE_INSENSITIVE | Pattern.MULTILINE | Pattern.DOTALL);
value = scriptPattern.matcher(value).replaceAll("");

// Remove any lonesome <iframe ...> tag 
scriptPattern = Pattern.compile("<[\r\n| | ]*iframe(.*?)>",
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 e-xpression(...) expressions 
scriptPattern = Pattern.compile("e-xpression\\((.*?)\\)",
Pattern.CASE_INSENSITIVE | Pattern.MULTILINE | Pattern.DOTALL);
value = scriptPattern.matcher(value).replaceAll("");

// Avoid javascript:... expressions 
scriptPattern = Pattern.compile("javascript[\r\n| | ]*:[\r\n| | ]*", Pattern.CASE_INSENSITIVE);
value = scriptPattern.matcher(value).replaceAll("");

// Avoid vbscript:... expressions 
scriptPattern = Pattern.compile("vbscript[\r\n| | ]*:[\r\n| | ]*", 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("");
}

final String[] keys = SQL_KEYS.split("\\|");

//预防SQL盲注
for (int i = 0; i < keys.length; i++)
{
value = value.replace(keys[i].toString(), "");
}

return value;
}

public static void main(String[] args)
{
String value = "<src='null' select=sele onmouseover='alert(1)'>";

System.out.println(xssEncode(value));
}
}

需要使用只需要配置号web.xml并复制这两个类到项目中，并且根据实际情况放开第一个类

/* Adminuser user = (Adminuser)req.getSession().getAttribute(Constant.ADMINLOGIN_SUCCESS);
if (user != null)
{
//如果是后台请求则不需要经过XSS请求过滤
chain.doFilter(request, response);
}
else
{*/

这部分代码即可使用。