source: https://www.securityfocus.com/bid/29846/info
Classic FTP is prone to a directory-traversal vulnerability because the application fails to sufficiently sanitize user-supplied input.
Exploiting this issue allows an attacker to write arbitrary files to locations outside of the application's current directory. This could help the attacker launch further attacks.
Classic FTP 1.02 for Microsoft Windows is vulnerable; other versions may also be affected.
Response to LIST:
\..\..\..\..\..\..\..\..\..\testfile.txt\r\n
/../../../../../../../../../testfile.txt\r\n