问题背景：由于公司需要整改的老系统的漏洞检查，而系统就是没有使用参数化SQL即拼接查询语句开发的程序，导致漏洞扫描出现大量SQL注入问题。

解决方法：最好的办法就是不写拼接SQL，改用参数化SQL，推荐新项目使用，老项目改起来比较麻烦，花费的时间也多，最后选择用全局SQL过滤器过滤前端发送的请求内容。

代码：

/// <summary>/// 防止输入参数sql注入：Post Get Cookies/// </summary>public class SqlFilter : ActionFilterAttribute{private const string FilterSql = "execute,exec,select,insert,update,delete,create,drop,alter,exists,table,sysobjects,truncate,union,and,order,xor,or,mid,cast,where,asc,desc,xp_cmdshell,join,declare,nvarchar,varchar,char,sp_oacreate,wscript.shell,xp_regwrite,',%,;,--";public override void OnActionExecuting(ActionExecutingContext filterContext){// -----------------------防 Post 注入-----------------------if (filterContext.HttpContext.Request.Form != null){var isReadonly = typeof(System.Collections.Specialized.NameValueCollection).GetProperty("IsReadOnly", BindingFlags.Instance | BindingFlags.NonPublic);//把 Form 属性改为可读写isReadonly?.SetValue(filterContext.HttpContext.Request.Form, false, null);for (var k = 0; k < filterContext.HttpContext.Request.Form.Count; k++){var inputKey = filterContext.HttpContext.Request.Form.Keys[k];var inputValue = filterContext.HttpContext.Request.Form[inputKey];var filters = FilterSql.Split(',');inputValue = filters.Aggregate(inputValue, (current, filterSql) => Regex.Replace(current, filterSql, "", RegexOptions.IgnoreCase));filterContext.HttpContext.Request.Form[inputKey] = inputValue;}}// -----------------------防 GET 注入-----------------------if (filterContext.HttpContext.Request.QueryString != null){var isReadonly = typeof(System.Collections.Specialized.NameValueCollection).GetProperty("IsReadOnly", BindingFlags.Instance | BindingFlags.NonPublic);//把 QueryString 属性改为可读写isReadonly?.SetValue(filterContext.HttpContext.Request.QueryString, false, null);for (var k = 0; k < filterContext.HttpContext.Request.QueryString.Count; k++){var inputKey = filterContext.HttpContext.Request.QueryString.Keys[k];var inputValue = filterContext.HttpContext.Request.QueryString[inputKey];var filters = FilterSql.Split(',');inputValue = filters.Aggregate(inputValue, (current, filterSql) => Regex.Replace(current, filterSql, "", RegexOptions.IgnoreCase));filterContext.HttpContext.Request.QueryString[inputKey] = inputValue;}}// -----------------------防 Cookies 注入-----------------------if (filterContext.HttpContext.Request.Cookies.Count > 0){var isReadonly = typeof(System.Collections.Specialized.NameValueCollection).GetProperty("IsReadOnly", BindingFlags.Instance | BindingFlags.NonPublic);//把 Cookies 属性改为可读写isReadonly?.SetValue(filterContext.HttpContext.Request.Cookies, false, null);for (var k = 0; k < filterContext.HttpContext.Request.Cookies.Count; k++){var inputKey = filterContext.HttpContext.Request.Cookies.Keys[k];var inputValue = filterContext.HttpContext.Request.Cookies[inputKey]?.Value;var filters = FilterSql.Split(',');inputValue = filters.Aggregate(inputValue, (current, filterSql) => Regex.Replace(current, filterSql, "", RegexOptions.IgnoreCase));if (!(filterContext.HttpContext.Request.Cookies[inputKey] is null)){filterContext.HttpContext.Request.Cookies[inputKey].Value = inputValue;}}}base.OnActionExecuting(filterContext);}}