我理解的sql注入就是一些人可以通過(guò)惡意的參數(shù)輸入，讓后臺(tái)執(zhí)行這段SQL，然后達(dá)到獲取數(shù)據(jù)或者破壞數(shù)據(jù)庫(kù)的目的！
舉個(gè)簡(jiǎn)單的查詢例子，后臺(tái)sql是拼接的：select * from Test where name='+參數(shù)傳遞+'；前臺(tái)頁(yè)面要求輸入name，那么黑客可以輸入： ';DROP TABLE Test;-- 不要小瞧這一段SQL代碼：
select * from Test where name=' ';DROP TABLE Test;--'；在SQL中是正確的，可執(zhí)行的，但是執(zhí)行后整個(gè)Test表都刪除了，網(wǎng)站崩潰！
最好的辦法就是不寫(xiě)拼接SQL，改用參數(shù)化SQL，推薦新項(xiàng)目使用。這里不做介紹，感興趣的朋友可以自行搜索一下，本文介紹的方法適合老項(xiàng)目，就是沒(méi)有使用參數(shù)化SQL開(kāi)發(fā)的程序。
將SQL一些危險(xiǎn)的關(guān)鍵字，還有注釋百分號(hào)以及分號(hào)這些根本在我們正常寫(xiě)代碼的時(shí)候根本不會(huì)出現(xiàn)的字符都過(guò)濾掉，這樣能最大限度的保證SQL執(zhí)行是安全的，代碼如下：
public class SqlFilter
{
public static void Filter()
{
string fileter_sql = "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,',%,;,--";
try
{
// -----------------------防 Post 注入-----------------------
if (HttpContext.Current.Request.Form != null)
{
PropertyInfo isreadonly = typeof(System.Collections.Specialized.NameValueCollection).GetProperty("IsReadOnly", BindingFlags.Instance | BindingFlags.NonPublic);
//把 Form 屬性改為可讀寫(xiě)
isreadonly.SetValue(HttpContext.Current.Request.Form, false, null);
for (int k = 0; k System.Web.HttpContext.Current.Request.Form.Count; k++)
{
string getsqlkey = HttpContext.Current.Request.Form.Keys[k];
string sqlstr = HttpContext.Current.Request.Form[getsqlkey];
string[] replace_sqls = fileter_sql.Split(',');
foreach (string replace_sql in replace_sqls)
{
sqlstr = Regex.Replace(sqlstr, replace_sql, "", RegexOptions.IgnoreCase);
}
HttpContext.Current.Request.Form[getsqlkey] = sqlstr;
}
}
// -----------------------防 GET 注入-----------------------
if (HttpContext.Current.Request.QueryString != null)
{
PropertyInfo isreadonly = typeof(System.Collections.Specialized.NameValueCollection).GetProperty("IsReadOnly", BindingFlags.Instance | BindingFlags.NonPublic);
//把 QueryString 屬性改為可讀寫(xiě)
isreadonly.SetValue(HttpContext.Current.Request.QueryString, false, null);
for (int k = 0; k System.Web.HttpContext.Current.Request.QueryString.Count; k++)
{
string getsqlkey = HttpContext.Current.Request.QueryString.Keys[k];
string sqlstr = HttpContext.Current.Request.QueryString[getsqlkey];
string[] replace_sqls = fileter_sql.Split(',');
foreach (string replace_sql in replace_sqls)
{
sqlstr = Regex.Replace(sqlstr, replace_sql, "", RegexOptions.IgnoreCase);
}
HttpContext.Current.Request.QueryString[getsqlkey] = sqlstr;
}
}
// -----------------------防 Cookies 注入-----------------------
if (HttpContext.Current.Request.Cookies != null)
{
PropertyInfo isreadonly = typeof(System.Collections.Specialized.NameValueCollection).GetProperty("IsReadOnly", BindingFlags.Instance | BindingFlags.NonPublic);
//把 Cookies 屬性改為可讀寫(xiě)
isreadonly.SetValue(HttpContext.Current.Request.Cookies, false, null);
for (int k = 0; k System.Web.HttpContext.Current.Request.Cookies.Count; k++)
{
string getsqlkey = HttpContext.Current.Request.Cookies.Keys[k];
string sqlstr = HttpContext.Current.Request.Cookies[getsqlkey].Value;
string[] replace_sqls = fileter_sql.Split(',');
foreach (string replace_sql in replace_sqls)
{
sqlstr = Regex.Replace(sqlstr, replace_sql, "", RegexOptions.IgnoreCase);
}
HttpContext.Current.Request.Cookies[getsqlkey].Value = sqlstr;
}
}
}
catch (Exception ex)
{
Console.WriteLine(ex.Message);
}
}
}
