GEN:SID 1:308
Message EXPLOIT NextFTP client overflow
Summary This event is generated when an attempt is made to exploit a buffer overflow condition in certain versions of NextFTP for Windows.
Impact Serious. System compromize presenting the attacker with the opportunity to execute arbitrary code.
Detailed Information Certain versions of the NextFTP client from ToxSoft contain a programming error that allows an FTP server to issue commands on the client via exploit code in the server reply.
Affected Systems  
Attack Scenarios Exploit scripts are available
Ease of Attack Simple. Exploits are available.
Corrective Action Upgrade to the latest non-affected version of the software.

Use Secure Shell (ssh) for file transfer as opposed to FTP.
Additional References CVE:
http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-1999-0671

Bugtraq:
http://www.securityfocus.com/bid/572
Rule References bugtraq: 572
cve: 1999-0671