cookie过滤注入脚本攻击与cookie设置加密的类的编写2017年8月17日

cookie（储存在用户本地终端上的数据）

我经常用于比如    1，验证码的校验

                             2，用户信息校验。

                             3，限制登陆次数校验。

cookie的脚本注入攻击

通过修改cookie里的值注入恶意代码，破解网站

如下面的案例:

新建一个web网页

1,书写一个设置cookie函数与读取cookie函数

2,写入一个用户名cookie 值为aaa 

3,读取cookie

 public partial class WebForm1 : System.Web.UI.Page
    {
        protected void Page_Load(object sender, EventArgs e)
        {
            
             Response.Write( getCookie("用户名").Value);
        }
        public static HttpCookie getCookie(string cookieName)
        {
            HttpRequest request = HttpContext.Current.Request;
            if (request != null)
                return request.Cookies[cookieName];
            return null;
        }
        public static void SetCookie(string cookieName, string value, DateTime? expires)
        {
            HttpResponse response = HttpContext.Current.Response;
            if (response != null)
            {
                HttpCookie cookie = response.Cookies[cookieName];
                if (cookie != null)
                {
                    cookie.Value = HttpUtility.UrlEncode(value);
                    if (expires != null)
                        cookie.Expires = expires.Value;
                    response.SetCookie(cookie);
                }
            }
        }
    }

　　　　//按下按钮设置cookie

 protected void Button1_Click(object sender, EventArgs e)
        {
            SetCookie("name", "aaa", DateTime.Now.AddHours(5));
        }

结果如下图所示：（浏览器采用欧鹏）

接着修改cookie

有入侵的<script>文件从cookie中注入 ，（欧鹏浏览器把有注入信息的cookie过滤），如果用http工具完全可以执行，这里就不演示了，讲讲解决方法

 

解决方法1：特殊字符的过滤：

 value = Regex.Replace(value, "[ \[ \] \^ \-_*×――(^)$%~!@#$…&%￥—+=<>《》!！??？:：•`·、。，；,.;"‘’“”-]", "").ToUpper();

将这些特殊的字符通过正则过滤掉

解决方法二加密：Base64加密

value = Base64.Encrypt(value);
Base64.Decrypt(HttpUtility.UrlDecode(request.Cookies[cookieName].Value.ToString()));
  public static string Encrypt(string text)
        {
            Rijndael crypt = Rijndael.Create();
            byte[] key = new byte[32] { 0X12, 0X70, 0X41, 0X8F, 0X33, 0X02, 0XE5, 0X45, 0X85, 0X05, 0X76, 0XAA, 0X7A, 0XAE, 0X79, 0X98, 0XA7, 0X33, 0X49, 0XFF, 0XE6, 0XAE, 0XBF, 0X8D, 0X8D, 0X20, 0X8A, 0X49, 0X31, 0X3A, 0X12, 0X40 };
            byte[] iv = new byte[16] { 0X38, 0X81, 0X41, 0X4B, 0XAA, 0X25, 0X9A, 0X34, 0XB3, 0X46, 0X78, 0X56, 0X03, 0X42, 0XF6, 0X69  };
            crypt.Key = key;
            crypt.IV = iv;
            MemoryStream ms = new MemoryStream();
            ICryptoTransform transtormEncode = new ToBase64Transform();
            //Base64编码
            CryptoStream csEncode = new CryptoStream(ms, transtormEncode, CryptoStreamMode.Write);
            CryptoStream csEncrypt = new CryptoStream(csEncode, crypt.CreateEncryptor(), CryptoStreamMode.Write);
            System.Text.UTF8Encoding enc = new System.Text.UTF8Encoding();
            byte[] rawData = enc.GetBytes(text);
            csEncrypt.Write(rawData, 0, rawData.Length);
            csEncrypt.FlushFinalBlock();
            byte[] encryptedData = new byte[ms.Length];
            ms.Position = 0;
            ms.Read(encryptedData, 0, (int)ms.Length);
            return enc.GetString(encryptedData);
        }
        /************************************************************************
        解密函数：*/
        public static string Decrypt(string text)
        {
            Rijndael crypt = Rijndael.Create();
            byte[] key = new byte[32] { 0X12, 0X70, 0X41, 0X8F, 0X33, 0X02, 0XE5, 0X45, 0X85, 0X05, 0X76, 0XAA, 0X7A, 0XAE, 0X79, 0X98, 0XA7, 0X33, 0X49, 0XFF, 0XE6, 0XAE, 0XBF, 0X8D, 0X8D, 0X20, 0X8A, 0X49, 0X31, 0X3A, 0X12, 0X40  };
            byte[] iv = new byte[16] { 0X38, 0X81, 0X41, 0X4B, 0XAA, 0X25, 0X9A, 0X34, 0XB3, 0X46, 0X78, 0X56, 0X03, 0X42, 0XF6, 0X69 };
            crypt.Key = key;
            crypt.IV = iv;
            MemoryStream ms = new MemoryStream();
            CryptoStream csDecrypt = new CryptoStream(ms, crypt.CreateDecryptor(), CryptoStreamMode.Write);
            ICryptoTransform transformDecode = new FromBase64Transform();
            CryptoStream csDecode = new CryptoStream(csDecrypt, transformDecode, CryptoStreamMode.Write);
            System.Text.UTF8Encoding enc = new System.Text.UTF8Encoding();
            byte[] rawData = enc.GetBytes(text);
            csDecode.Write(rawData, 0, rawData.Length);
            csDecode.FlushFinalBlock();
            byte[] decryptedData = new byte[ms.Length];
            ms.Position = 0;
            ms.Read(decryptedData, 0, (int)ms.Length);
            return (enc.GetString(decryptedData));
        }

当然也可以两种都加先过滤在加密