FTP
Last updated
Last updated
Source CTF and HTB Academy
Usually on port 21
The File Transfer Protocol (FTP) is one of the oldest protocols on the Internet. The FTP runs within the application layer of the TCP/IP protocol stack. Thus, it is on the same layer as HTTP or POP. These protocols also work with the support of browsers or email clients to perform their services. There are also special FTP programs for the File Transfer Protocol.
find / -type f -name ftp* 2>/dev/null | grep scripts find all the nmap scripts for ftp and choose the ones you wish to use
sudo nmap -sV -p21 -sC -A 10.129.14.136
nc -nv 10.129.14.136 21
telnet 10.129.14.136 21
openssl s_client -connect 10.129.14.136:21 -starttls ftp
Check if anonymous FTP is enabled, if so check if you can downloads files. If so you can RCE. Check out to have an example of this.
If you do not have write access you could still find interesting and useful files like passwords or else.
One of the most used FTP servers on Linux-based distributions is .
sudo apt install vsftpd install it
cat /etc/vsftpd.conf | grep -v "#" interesting config to check
cat /etc/ftpusers file used to deny certain users access to the FTP service
anonymous_enable=YES
Allowing anonymous login?
anon_upload_enable=YES
Allowing anonymous to upload files?
anon_mkdir_write_enable=YES
Allowing anonymous to create new directories?
no_anon_password=YES
Do not ask anonymous for password?
anon_root=/home/username/ftp
Directory for anonymous.
write_enable=YES
Allow the usage of FTP commands: STOR, DELE, RNFR, RNTO, MKD, RMD, APPE, and SITE?
ftp <TARGET-IP> <port> you will need to specify the port in case it is not port 21 if it is 21 you do not need to specify
wget -m --no-passive ftp://username:password@IP:2121 --starttls ftp
wget ftp://username:password@ftp_server_address/path/to/file
sudo apt install lftp
lftp -p 2121 -u anonymous, 10.10.10.10
status will show configurations
debug
trace
ls -R list file recursively
get filename download a file
put filename upload a file
wget -m --no-passive ftp://anonymous:anonymous@10.129.14.136 Downaload all available files
tree . inspect all files downloaded
Upload a file
touch file create a file
put file put it in the ftp server
Do not forget ls -al (to see hidden files)
dirmessage_enable=YES
Show a message when they first enter a new directory?
chown_uploads=YES
Change ownership of anonymously uploaded files?
chown_username=username
User who is given ownership of anonymously uploaded files.
local_enable=YES
Enable local users to login?
chroot_local_user=YES
Place local users into their home directory?
chroot_list_enable=YES
Use a list of local users that will be placed in their home directory?
hide_ids=YES
All user and group information in directory listings will be displayed as "ftp".
ls_recurse_enable=YES
Allows the use of recurse listings.
Trivial File Transfer Protocol (TFTP) is simpler than FTP and performs file transfers between client and server processes. However, it does not provide user authentication and other valuable features supported by FTP. In addition, while FTP uses TCP, TFTP uses UDP, making it an unreliable protocol and causing it to use UDP-assisted application layer recovery.
connect
Sets the remote host, and optionally the port, for file transfers.
get
Transfers a file or set of files from the remote host to the local host.
put
Transfers a file or set of files from the local host onto the remote host.
quit
Exits tftp.
status
Shows the current status of tftp, including the current transfer mode (ascii or binary), connection status, time-out value, and so on.
verbose
Turns verbose mode, which displays additional information during file transfer, on or off.
An FTP bounce attack is a network attack that uses FTP servers to deliver outbound traffic to another device on the network. The attacker uses a PORT command to trick the FTP connection into running commands and getting information from a device other than the intended server.
Consider we are targetting an FTP Server FTP_DMZ exposed to the internet. Another device within the same network, Internal_DMZ, is not exposed to the internet. We can use the connection to the FTP_DMZ server to scan Internal_DMZ using the FTP Bounce attack and obtain information about the server's open ports. Then, we can use that information as part of our attack against the infrastructure.
The Nmap -b flag can be used to perform an FTP bounce attack:
PASV enter
Source
This vulnerability is for an FTP service that does not correctly process the HTTP PUT request and leads to an authenticated directory/path traversal, and arbitrary file write vulnerability. This vulnerability allows us to write files outside the directory to which the service has access. Exploitation
