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296 lines
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296 lines
14 KiB
Markdown
# 21 - Pentesting FTP
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<details>
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<summary><a href="https://cloud.hacktricks.xyz/pentesting-cloud/pentesting-cloud-methodology"><strong>☁️ HackTricks Cloud ☁️</strong></a> -<a href="https://twitter.com/hacktricks_live"><strong>🐦 Twitter 🐦</strong></a> - <a href="https://www.twitch.tv/hacktricks_live/schedule"><strong>🎙️ Twitch 🎙️</strong></a> - <a href="https://www.youtube.com/@hacktricks_LIVE"><strong>🎥 Youtube 🎥</strong></a></summary>
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</details>
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## Basic Information
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The **File Transfer Protocol (FTP**) is a standard network protocol used for the transfer of computer files between a client and server on a computer network.\
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It is a **plain-text** protocol that uses as **new line character `0x0d 0x0a`** so sometimes you need to **connect using `telnet`** or **`nc -C`**.
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**Default Port:** 21
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```
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PORT STATE SERVICE
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21/tcp open ftp
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```
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### Connections Active & Passive
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In **Active FTP** the FTP **client** first **initiates** the control **connection** from its port N to FTP Servers command port – port 21. The **client** then **listens** to port **N+1** and sends the port N+1 to FTP Server. FTP **Server** then **initiates** the data **connection**, from **its port M to the port N+1** of the FTP Client.
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But, if the FTP Client has a firewall setup that controls the incoming data connections from outside, then active FTP may be a problem. And, a feasible solution for that is Passive FTP.
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In **Passive FTP**, the client initiates the control connection from its port N to the port 21 of FTP Server. After this, the client issues a **passv comand**. The server then sends the client one of its port number M. And the **client** **initiates** the data **connection** from **its port P to port M** of the FTP Server.
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Source: [https://www.thesecuritybuddy.com/vulnerabilities/what-is-ftp-bounce-attack/](https://www.thesecuritybuddy.com/vulnerabilities/what-is-ftp-bounce-attack/)
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### Connection debugging
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The **FTP** commands **`debug`** and **`trace`** can be used to see **how is the communication occurring**.
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## Enumeration
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### Banner Grabbing
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```bash
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nc -vn <IP> 21
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openssl s_client -connect crossfit.htb:21 -starttls ftp #Get certificate if any
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```
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### Connect to FTP using starttls
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```
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lftp
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lftp :~> set ftp:ssl-force true
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lftp :~> set ssl:verify-certificate no
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lftp :~> connect 10.10.10.208
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lftp 10.10.10.208:~> login
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Usage: login <user|URL> [<pass>]
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lftp 10.10.10.208:~> login username Password
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```
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### Unauth enum
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With **nmap**
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```bash
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sudo nmap -sV -p21 -sC -A 10.10.10.10
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```
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You can us the commands `HELP` and `FEAT` to obtain some information of the FTP server:
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```
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HELP
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214-The following commands are recognized (* =>'s unimplemented):
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214-CWD XCWD CDUP XCUP SMNT* QUIT PORT PASV
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214-EPRT EPSV ALLO* RNFR RNTO DELE MDTM RMD
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214-XRMD MKD XMKD PWD XPWD SIZE SYST HELP
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214-NOOP FEAT OPTS AUTH CCC* CONF* ENC* MIC*
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214-PBSZ PROT TYPE STRU MODE RETR STOR STOU
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214-APPE REST ABOR USER PASS ACCT* REIN* LIST
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214-NLST STAT SITE MLSD MLST
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214 Direct comments to root@drei.work
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FEAT
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211-Features:
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PROT
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CCC
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PBSZ
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AUTH TLS
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MFF modify;UNIX.group;UNIX.mode;
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REST STREAM
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MLST modify*;perm*;size*;type*;unique*;UNIX.group*;UNIX.mode*;UNIX.owner*;
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UTF8
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EPRT
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EPSV
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LANG en-US
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MDTM
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SSCN
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TVFS
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MFMT
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SIZE
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211 End
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STAT
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#Info about the FTP server (version, configs, status...)
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```
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### Anonymous login
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_anonymous : anonymous_\
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_anonymous :_\
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_ftp : ftp_
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```bash
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ftp <IP>
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>anonymous
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>anonymous
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>ls -a # List all files (even hidden) (yes, they could be hidden)
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>binary #Set transmission to binary instead of ascii
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>ascii #Set transmission to ascii instead of binary
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>bye #exit
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```
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### [Brute force](../../generic-methodologies-and-resources/brute-force.md#ftp)
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Here you can find a nice list with default ftp credentials: [https://github.com/danielmiessler/SecLists/blob/master/Passwords/Default-Credentials/ftp-betterdefaultpasslist.txt](https://github.com/danielmiessler/SecLists/blob/master/Passwords/Default-Credentials/ftp-betterdefaultpasslist.txt)
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### Automated
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Anon login and bounce FTP checks are perform by default by nmap with **-sC** option or:
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```bash
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nmap --script ftp-* -p 21 <ip>
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```
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## Browser connection
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You can connect to a FTP server using a browser (like Firefox) using a URL like:
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```bash
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ftp://anonymous:anonymous@10.10.10.98
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```
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Note that if a **web application** is sending data controlled by a user **directly to a FTP server** you can send double URL encode `%0d%0a` (in double URL encode this is `%250d%250a`) bytes and make the **FTP server perform arbitrary actions**. One of this possible arbitrary actions is to download content from a users controlled server, perform port scanning or try to talk to other plain-text based services (like http).
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## Download all files from FTP
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```bash
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wget -m ftp://anonymous:anonymous@10.10.10.98 #Donwload all
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wget -m --no-passive ftp://anonymous:anonymous@10.10.10.98 #Download all
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```
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## Some FTP commands
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* **`USER username`**
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* **`PASS password`**
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* **`HELP`** The server indicates which commands are supported
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* **`PORT 127,0,0,1,0,80`**This will indicate the FTP server to establish a connection with the IP 127.0.0.1 in port 80 (_you need to put the 5th char as "0" and the 6th as the port in decimal or use the 5th and 6th to express the port in hex_).
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* **`EPRT |2|127.0.0.1|80|`**This will indicate the FTP server to establish a TCP connection (_indicated by "2"_) with the IP 127.0.0.1 in port 80. This command **supports IPv6**.
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* **`LIST`** This will send the list of files in current folder
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* **`LIST -R`** List recursively (if allowed by the server)
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* **`APPE /path/something.txt`** This will indicate the FTP to store the data received from a **passive** connection or from a **PORT/EPRT** connection to a file. If the filename exists, it will append the data.
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* **`STOR /path/something.txt`** Like `APPE` but it will overwrite the files
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* **`STOU /path/something.txt`** Like `APPE`, but if exists it won't do anything.
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* **`RETR /path/to/file`** A passive or a port connection must be establish. Then, the FTP server will send the indicated file through that connection
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* **`REST 6`** This will indicate the server that next time it send something using `RETR` it should start in the 6th byte.
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* **`TYPE i`** Set transfer to binary
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* **`PASV`** This will open a passive connection and will indicate the user were he can connects
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* **`PUT /tmp/file.txt`** Upload indicated file to the FTP
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.png>)
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## FTPBounce attack
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Some FTP servers allow the command PORT. This command can be used to indicate to the server that you wants to connect to other FTP server at some port. Then, you can use this to scan which ports of a host are open through a FTP server.
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[**Learn here how to abuse a FTP server to scan ports.**](ftp-bounce-attack.md)
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You could also abuse this behaviour to make a FTP server interact with other protocols. You could **upload a file containing an HTTP request** and make the vulnerable FTP server **send it to an arbitrary HTTP server** (_maybe to add a new admin user?_) or even upload a FTP request and make the vulnerable FTP server download a file for a different FTP server.\
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The theory is easy:
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1. **Upload the request (inside a text file) to the vulnerable server.** Remember that if you want to talk with another HTTP or FTP server you need to change lines with `0x0d 0x0a`
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2. **Use `REST X` to avoid sending the characters you don't want to send** (maybe to upload the request inside the file you needed to put some image header at the beginning)
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3. **Use `PORT`to connect to the arbitrary server and service**
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4. **Use `RETR`to send the saved request to the server.**
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Its highly probably that this **will throw an error like** _**Socket not writable**_ **because the connection doesn't last enough to send the data with `RETR`**. Suggestions to try to avoid that are:
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* If you are sending an HTTP request, **put the same request one after another** until **\~0.5MB** at least. Like this:
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{% file src="../../.gitbook/assets/posts (1).txt" %}
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posts.txt
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{% endfile %}
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* Try to **fill the request with "junk" data relative to the protocol** (talking to FTP maybe just junk commands or repeating the `RETR`instruction to get the file)
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* Just **fill the request with a lot of null characters or others** (divided on lines or not)
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Anyway, here you have an [old example about how to abuse this to make a FTP server download a file from a different FTP server.](ftp-bounce-download-2oftp-file.md)
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## Filezilla Server Vulnerability
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**FileZilla** usually **binds** to **local** an **Administrative service** for the **FileZilla-Server** (port 14147). If you can create a **tunnel** from **your machine** to access this port, you can **connect** to **it** using a **blank password** and **create** a **new user** for the FTP service.
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## Config files
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```
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ftpusers
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ftp.conf
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proftpd.conf
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vsftpd.conf
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```
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### Post-Exploitation
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The default configuration of vsFTPd can be found in `/etc/vsftpd.conf`. In here, you could find some dangerous settings:
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* `anonymous_enable=YES`
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* `anon_upload_enable=YES`
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* `anon_mkdir_write_enable=YES`
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* `anon_root=/home/username/ftp` - Directory for anonymous.
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* `chown_uploads=YES` - Change ownership of anonymously uploaded files
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* `chown_username=username` - User who is given ownership of anonymously uploaded files
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* `local_enable=YES` - Enable local users to login
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* `no_anon_password=YES` - Do not ask anonymous for password
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* `write_enable=YES` - Allow commands: STOR, DELE, RNFR, RNTO, MKD, RMD, APPE, and SITE
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### Shodan
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* `ftp`
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* `port:21`
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## HackTricks Automatic Commands
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```
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Protocol_Name: FTP #Protocol Abbreviation if there is one.
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Port_Number: 21 #Comma separated if there is more than one.
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Protocol_Description: File Transfer Protocol #Protocol Abbreviation Spelled out
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Entry_1:
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Name: Notes
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Description: Notes for FTP
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Note: |
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Anonymous Login
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-bi <<< so that your put is done via binary
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wget --mirror 'ftp://ftp_user:UTDRSCH53c"$6hys@10.10.10.59'
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^^to download all dirs and files
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wget --no-passive-ftp --mirror 'ftp://anonymous:anonymous@10.10.10.98'
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if PASV transfer is disabled
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https://book.hacktricks.xyz/pentesting/pentesting-ftp
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Entry_2:
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Name: Banner Grab
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Description: Grab FTP Banner via telnet
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Command: telnet -n {IP} 21
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Entry_3:
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Name: Cert Grab
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Description: Grab FTP Certificate if existing
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Command: openssl s_client -connect {IP}:21 -starttls ftp
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Entry_4:
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Name: nmap ftp
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Description: Anon login and bounce FTP checks are performed
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Command: nmap --script ftp-* -p 21 {IP}
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Entry_5:
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Name: Browser Connection
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Description: Connect with Browser
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Note: ftp://anonymous:anonymous@{IP}
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Entry_6:
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Name: Hydra Brute Force
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Description: Need Username
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Command: hydra -t 1 -l {Username} -P {Big_Passwordlist} -vV {IP} ftp
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Entry_7:
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Name: consolesless mfs enumeration ftp
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Description: FTP enumeration without the need to run msfconsole
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Note: sourced from https://github.com/carlospolop/legion
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Command: msfconsole -q -x 'use auxiliary/scanner/ftp/anonymous; set RHOSTS {IP}; set RPORT 21; run; exit' && msfconsole -q -x 'use auxiliary/scanner/ftp/ftp_version; set RHOSTS {IP}; set RPORT 21; run; exit' && msfconsole -q -x 'use auxiliary/scanner/ftp/bison_ftp_traversal; set RHOSTS {IP}; set RPORT 21; run; exit' && msfconsole -q -x 'use auxiliary/scanner/ftp/colorado_ftp_traversal; set RHOSTS {IP}; set RPORT 21; run; exit' && msfconsole -q -x 'use auxiliary/scanner/ftp/titanftp_xcrc_traversal; set RHOSTS {IP}; set RPORT 21; run; exit'
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```
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<details>
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<summary><a href="https://cloud.hacktricks.xyz/pentesting-cloud/pentesting-cloud-methodology"><strong>☁️ HackTricks Cloud ☁️</strong></a> -<a href="https://twitter.com/hacktricks_live"><strong>🐦 Twitter 🐦</strong></a> - <a href="https://www.twitch.tv/hacktricks_live/schedule"><strong>🎙️ Twitch 🎙️</strong></a> - <a href="https://www.youtube.com/@hacktricks_LIVE"><strong>🎥 Youtube 🎥</strong></a></summary>
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* Do you work in a **cybersecurity company**? Do you want to see your **company advertised in HackTricks**? or do you want to have access to the **latest version of the PEASS or download HackTricks in PDF**? Check the [**SUBSCRIPTION PLANS**](https://github.com/sponsors/carlospolop)!
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* Discover [**The PEASS Family**](https://opensea.io/collection/the-peass-family), our collection of exclusive [**NFTs**](https://opensea.io/collection/the-peass-family)
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* **Share your hacking tricks by submitting PRs to the [hacktricks repo](https://github.com/carlospolop/hacktricks) and [hacktricks-cloud repo](https://github.com/carlospolop/hacktricks-cloud)**.
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</details>
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