Statement: Local / Remote D.o.S Attack in War FTP Daemon 1.70

[jgaa () JGAA COM (Jarle Aase)]

War FTP Daemon 1.70 is beta software, and will be replaced with a new major version early next year. The development on 
the 1.70 source tree has stopped, and no new versions of 1.7* is planned, - unless some serious security problems are 
reported. 

The Remote D.o.S Attack does stall the server. There is however no indication of any buffer-overflow problems or other 
security-related problems. 

The attack is logged to the server-log if the default log options are enabled. An attack of this type may look like 
this in the server log:

I 12/17/99 02:19:43 FTPD:test21:0001 (User=18446744073709551615  ) [WarFTPD::OnAccept()] Client 
(193.91.161.151:4496->193.91.161.20:21) is connected to the FTP server.
I 12/17/99 02:19:43 FTPD:test21:0002 (User=18446744073709551615  ) [WarFTPD::OnAccept()] Client 
(193.91.161.151:4497->193.91.161.20:21) is connected to the FTP server.
I 12/17/99 02:19:43 FTPD:test21:0003 (User=18446744073709551615  ) [WarFTPD::OnAccept()] Client 
(193.91.161.151:4498->193.91.161.20:21) is connected to the FTP server.
...

A large number of connections from a single IP address at the same time indicate an attack.

If logging of debug messages are enabled, the log will also show something like this:

D 12/17/99 02:19:48 FTPD:test21:000e (User=18446744073709551615  ) [WarFTPDControlSck::OnCommand()] Got command 
".blsJw{aP.q"
D 12/17/99 02:19:48 FTPD:test21:000e (User=18446744073709551615  ) [WarFTPDControlSck::OnCommand()] Got command 
"}DGqDYH"
D 12/17/99 02:19:48 FTPD:test21:000e (User=18446744073709551615  ) [WarFTPDControlSck::OnCommand()] Got command "05(N^ 
mPӒ¹à Ìá
ø2Qc|"

War FTP Daemon 3.0 will have three levels of protection for this and similar attacks:

   - 1) Dynamic interaction with firewall software to lock out flooders
   - 2) Fast accept(); close(); cycles when connections are made too fast
   - 3) Traffic analysis and temporary lock-outs for hosts that make
        too many connection attempts (hammering protection).

Jarle

- 
Jarle Aase
Author of freeware.

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<no need to argue - just kill'em all!> 

> -----Original Message-----
> From: Bugtraq List [mailto:BUGTRAQ () SECURITYFOCUS COM]On Behalf Of Ussr
> Labs
> Sent: Tuesday, December 14, 1999 7:57 AM
> To: BUGTRAQ () SECURITYFOCUS COM
> Subject: Local / Remote D.o.S Attack in War FTP Daemon 1.70
> Vulnerability
>
>
> Local / Remote D.o.S Attack in War FTP Daemon 1.70 Vulnerability
>
> PROBLEM
>
> UssrLabs found a Local/Remote DoS Attack in War FTP Daemon 1.70
> the buffer overflow is caused by a Multiples connections at the same time
> (over 60) in the ftp server , and some characters in the login name.
>
> There is not much to expand on.... just a simple hole
>
> For the source / binary of this remote / local D.O.S
> Go to: http://www.ussrback.com/
>
> Vendor Status:
> Contacted.
>
> Vendor   Url: http://www.jgaa.com
> Program Url: http://www.jgaa.com/warftpd.htm
>
> Credit: USSRLABS
>
> SOLUTION
>     Nothing yet.
>
>
> u n d e r g r o u n d  s e c u r i t y  s y s t e m s  r e s e a r c h
> http://www.ussrback.com