【JAVA】跨站脚本攻击(XSS攻击)
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一 跨网站脚本

跨网站脚本(Cross-site scripting,通常简称为XSS或跨站脚本或跨站脚本攻击)是一种网站应用程序的安全漏洞攻击,是代码注入的一种。它允许恶意用户将代码注入到网页上,其他用户在观看网页时就会受到影响。这类攻击通常包含了HTML以及用户端脚本语言。 

XSS攻击通常指的是通过利用网页开发时留下的漏洞,通过巧妙的方法注入恶意指令代码到网页,使用户加载并执行攻击者恶意制造的网页程序。这些恶意网页程序通常是JavaScript,但实际上也可以包括Java, VBScript, ActiveX, Flash 或者甚至是普通的HTML。攻击成功后,攻击者可能得到包括但不限于更高的权限(如执行一些操作)、私密网页内容、会话和cookie等各种内容。 
二 常用的XSS攻击手段和目的 
  盗用 cookie ,获取敏感信息。 
利用植入 Flash ,通过 crossdomain 权限设置进一步获取更高权限;或者利用Java等得到类似的操作。 
利用 iframe、frame、XMLHttpRequest或上述Flash等方式,以(被攻击)用户的身份执行一些管理动作,或执行一些一般的如发微博、加好友、发私信等操作。 
  利用可被攻击的域受到其他域信任的特点,以受信任来源的身份请求一些平时不允许的操作,如进行不当的投票活动。 
  在访问量极大的一些页面上的XSS可以攻击一些小型网站,实现DDoS攻击的效果。 
三 漏洞的防御和利用 
避免XSS的方法之一主要是将用户所提供的内容进行过滤,许多语言都有提供对HTML的过滤: 

    PHP的htmlentities()或是htmlspecialchars()。 
    Python的cgi.escape()。 
    ASP的Server.HTMLEncode()。 
    ASP.NET的Server.HtmlEncode()或功能更强的Microsoft Anti-Cross Site Scripting Library 
    Java的xssprotect(Open Source Library)。 
    Node.js的node-validator。 

四 解决方案

我碰到的问题解决方案主要是对request请求的parameter 参数做过滤与字符转义

<web-app version="2.4" xmlns="http://java.sun.com/xml/ns/j2ee"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee http://java.sun.com/xml/ns/j2ee/web-app_2_4.xsd">

<filter>
<filter-name>XssSqlFilter</filter-name>
<filter-class>framework.corenew.XssFilter</filter-class>
</filter>
<filter-mapping>
<filter-name>XssSqlFilter</filter-name>
<url-pattern>/*</url-pattern>
<dispatcher>REQUEST</dispatcher>
</filter-mapping>

</web-app>

XssFilter: 

import java.io.IOException;
import java.util.Enumeration;
import java.util.regex.Pattern;

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;

/**
* <code>{@link CharLimitFilter}</code>
*
* 拦截防止注入漏洞
*
* @author Administrator
*/
public class XssFilter implements Filter {

FilterConfig filterConfig = null;

public void init(FilterConfig filterConfig) throws ServletException {
this.filterConfig = filterConfig;
}

public void destroy() {
this.filterConfig = null;
}

public void doFilter(ServletRequest request, ServletResponse response,
FilterChain chain) throws IOException, ServletException {


chain.doFilter(new XssHttpServletRequestWrapperNew(
(HttpServletRequest) request), response);


}

}

XssHttpServletRequestWrapperNew: 

import java.text.CharacterIterator;
import java.text.StringCharacterIterator;
import java.util.regex.Pattern;

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

public class XssHttpServletRequestWrapperNew extends HttpServletRequestWrapper {

HttpServletRequest orgRequest = null;

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

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

/**
* 对一些特殊字符进行转义
*
*
*/
public static String HTMLEncode(String aText) {
final StringBuilder result = new StringBuilder();
final StringCharacterIterator iterator = new StringCharacterIterator(
aText);
char character = iterator.current();
while (character != CharacterIterator.DONE) {
if (character == '<') {
result.append("<");
} else if (character == '>') {
result.append(">");
} else if (character == '&') {
result.append("&");
} else if (character == '\"') {
result.append("\"");
} else {
// the char is not a special one
// add it to the result as is
result.append(character);
}
character = iterator.next();
}
return result.toString();
}
/**
* 覆盖getHeader方法,将参数名和参数值都做xss过滤。 如果需要获得原始的值,则通过super.getHeaders(name)来获取
* 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
* 目前xssProject对注入代码要求是必须开始标签和结束标签(如<script></script>)正确匹配才能解析,否则报错;因此只能替换调xssProject换为自定义实现
* @param s
* @return
*/
private static String xssEncode(String s) {
//
// if (s == null || s.isEmpty()) {
// return s;
// }
//
// StringReader reader = new StringReader(s);
// StringWriter writer = new StringWriter();
// try {
// HTMLParser.process(reader, writer, new XSSFilter(), true);
//
// String result = writer.toString();
//
// System.out.println("xssEncode-------------------------" + s + " = "
// + result);
//
// return result;
// } catch (NullPointerException e) {
// return s;
// } catch (Exception ex) {
// ex.printStackTrace();
// }
//
// return null;
if (s == null || s.isEmpty()) {
return s;
}
String result = stripXSS(s);
if (null != result) {
result = escape(result);
}
return result;
}
public static String escape(String 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('\');// 全角斜线
break;
case '%':
sb.append('%'); // 全角冒号
break;
default:
sb.append(c);
break;
}
}
return sb.toString();
}
private static String stripXSS(String value) {
if (value != null) {
// NOTE: It's highly recommended to use the ESAPI library and
// uncomment the following line to
// avoid encoded attacks.
// value = ESAPI.encoder().canonicalize(value);
// Avoid null characters
value = value.replaceAll("", "");
// 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 vbscript:... expressions
scriptPattern = Pattern.compile("vbscript:",
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("<iframe>(.*?)</iframe>",
Pattern.CASE_INSENSITIVE);
value = scriptPattern.matcher(value).replaceAll("");
scriptPattern = Pattern.compile("</iframe>",
Pattern.CASE_INSENSITIVE);
value = scriptPattern.matcher(value).replaceAll("");
// Remove any lonesome <script ...> tag
scriptPattern = Pattern.compile("<iframe(.*?)>",
Pattern.CASE_INSENSITIVE | Pattern.MULTILINE
| Pattern.DOTALL);
value = scriptPattern.matcher(value).replaceAll("");
}
return value;
}
/**
* 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 XssHttpServletRequestWrapperNew) {
return ((XssHttpServletRequestWrapperNew) req).getOrgRequest();
}
return req;
}
}


转:https://blog.csdn.net/a364726306/article/details/51917204

 

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