前端攻击-xss攻击防御
近期做的一些项目的安全级别比较高一点 ,所以需要去xss攻击进行防御
XSS是一种存在Web应用中,允许黑客以最终用户的身份向Web应用注入恶意脚本,以愚弄其他用户或获取其他用户重要数据和隐私信息为目的的一种攻击形式。XSS可使用的技术有JavaScript、VBScript、 ActiveX、 或 Flash, 且通常通过页面表单提交注入到web应用中并最终在用户的浏览器客户端执行。
危害:XSS可能造成的危害包括:将使用者浏览器导向恶意网站、偷取使用者的cookie、将使用者浏览器导向钓鱼网站,以骗取账号密码等个人资料、安装恶意后门木马、安置web浏览器炸弹等。XSS攻击介于攻击者与使用者之间的攻防战,并不会对server主机有任何威胁,所以才被称为跨站脚本攻击,意思即是:攻击者使用某些语言(脚本)跨过主机对使用者进行攻击。
前台校验
function xssCheck(str,reg){ return str ? str.replace(reg || /[&<">'](?:(amp|lt|quot|gt|#39|nbsp|#\d+);)?/g, function (a, b) { if(b){ return a; }else{ return { '<':'<', '&':'&', '"':'"', '>':'>', "'":''', }[a] } }) : ''; }
后台 java 会被提交到服务端的所有数据进行过滤
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import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletRequestWrapper; import java.util.HashMap; import java.util.Iterator; import java.util.Map; import java.util.regex.Pattern; public class XssUtil extends HttpServletRequestWrapper { private HttpServletRequest request; public XssUtil(HttpServletRequest request) { super(request); this.request = request; } /** * 重写getParameter方法 */ @Override public String getParameter(String name) { String value = super.getParameter(name); if (value == null) { return null; } value = format(value); return value; } /** * 重写getParameterMap */ @Override @SuppressWarnings("unchecked") 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] = format(values[i]); } } entry.setValue(values); } return paramMap; } /** * 重写getParameterValues */ @Override public String[] getParameterValues(String name) { String[] values = super.getParameterValues(name); if (values == null) { return null; } int count = values.length; String[] encodedValues = new String[count]; for (int i = 0; i < count; i++) { encodedValues[i] = format(values[i]); } return encodedValues; } /** * 重写getHeader */ @Override public String getHeader(String name) { // TODO Auto-generated method stub return format(super.getHeader(name)); } public String filter(String message) { if (message == null) return (null); message = format(message); return message; } /** * @desc 统一处理特殊字符的方法,替换掉sql和js的特殊字符 * @param name 要替换的字符 */ private String format(String name) { return xssEncode(name); } /** * 将容易引起xss & sql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(">");// 转义大于号 break; case '<': sb.append("<");// 转义小于号 break; case '\'': sb.append("'");// 转义单引号 break; case '\"': sb.append(""");// 转义双引号 break; case '&': sb.append("&");// 转义& break; case '#': sb.append("#");// 转义# break; default: sb.append(c); break; } } return sb.toString(); } /** * * 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) { // 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("<[\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(""); // 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(""); } return value; } }