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java 防止 XSS 攻击的常用方法

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java 防止 XSS 攻击的常用方法

1. 自己写 filter 拦截来实现,但要注意的时,在WEB.XML 中配置 filter 的时候,请将这个 filter 放在第一位.

2. 采用开源的实现 ESAPI library ,参考网址:

3. 可以采用spring 里面提供的工具类来实现.

一, 第一种方法。

web.xml文件Filter配置

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<!-- 配置防SQL注入过滤器 --> <filter> <filter-name>XssFilter</filter-name> <filter-class>新编写XssFilter路径</filter-class> </filter> <filter-mapping> <filter-name>XssFilter</filter-name> <url-pattern>/*</url-pattern> </filter-mapping>

编写Filter过滤器

public class XSSFilter implements Filter { @Override public void init(FilterConfig filterConfig) throws ServletException { } @Override public void destroy() { } @Override public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException { chain.doFilter(new XSSRequestWrapper((HttpServletRequest) request), response); }}

再实现 ServletRequest 的包装类

import java.util.regex.Pattern;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletRequestWrapper;public class XSSRequestWrapper extends HttpServletRequestWrapper { public XSSRequestWrapper(HttpServletRequest servletRequest) { super(servletRequest); } @Override public String[] getParameterValues(String parameter) { String[] values = super.getParameterValues(parameter); if (values == null) { return null; } int count = values.length; String[] encodedValues = new String[count]; for (int i = 0; i < count; i++) { encodedValues[i] = stripXSS(values[i]); } return encodedValues; } @Override public String getParameter(String parameter) { String value = super.getParameter(parameter); return stripXSS(value); } @Override public String getHeader(String name) { String value = super.getHeader(name); return stripXSS(value); } private 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(""); } return value; }}

例子中注释的部分,就是采用 ESAPI library 来防止XSS攻击的,推荐使用.

当然,我还看到这样一种办法,将所有的编程全角字符的解决方式,但个人觉得并没有上面这种用正则表达式替换的好

private static String xssEncode(String s) { if (s == null || s.equals("")) { return 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('\\'); sb.append('\''); sb.append('\\'); sb.append('\''); break; case '\"': sb.append('\\'); 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 ':': sb.append(':');// 全角冒号 break; case '%': sb.append("\\\\%"); break; default: sb.append(c); break; } } return sb.toString(); }

当然,还有如下更简单的方式:

private String cleanXSS(String value) { //You'll need to remove the spaces from the html entities below value = value.replaceAll("<", "& lt;").replaceAll(">", "& gt;"); value = value.replaceAll("\\(", "& #40;").replaceAll("\\)", "& #41;"); value = value.replaceAll("'", "& #39;"); value = value.replaceAll("eval\\((.*)\\)", ""); value = value.replaceAll("[\\\"\\\'][\\s]*javascript:(.*)[\\\"\\\']", "\"\""); value = value.replaceAll("script", ""); return value; }

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在后台或者用spring 如何实现呢:

首先添加一个jar包:commons-lang-2.5.jar ,然后在后台调用这些函数:

StringEscapeUtils.escapeHtml(string); StringEscapeUtils.escapeJavaScript(string); StringEscapeUtils.escapeSql(string);

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