Nmap NSE net: smb-os-discovery

2011-06-01T00:00:00
ID OPENVAS:104028
Type openvas
Reporter NSE-Script: The Nmap Security Scanner; NASL-Wrapper: Greenbone Networks GmbH
Modified 2017-03-06T00:00:00

Description

Attempts to determine the operating system, computer name, domain, and current time over the SMB protocol (ports 445 or 139). This is done by starting a session with the anonymous account (or with a proper user account, if one is given; it likely doesn't make a difference); in response to a session starting, the server will send back all this information.

Some systems, like Samba, will blank out their name (and only send their domain). Other systems (like embedded printers) will simply leave out the information. Other systems will blank out various pieces (some will send back 0 for the current time, for example).

Retrieving the name and operating system of a server is a vital step in targeting an attack against it, and this script makes that retrieval easy. Additionally, if a penetration tester is choosing between multiple targets, the time can help identify servers that are being poorly maintained (for more information/random thoughts on using the time, see http://www.skullsecurity.org/blog/?p=76.

Although the standard 'smb*' script arguments can be used, they likely won't change the outcome in any meaningful way.

SYNTAX:

smbbasic: Forces the authentication to use basic security, as opposed to 'extended security'. Against most modern systems, extended security should work, but there may be cases where you want to force basic. There's a chance that you'll get better results for enumerating users if you turn on basic authentication.

smbport: Override the default port choice. If 'smbport' is open, it's used. It's assumed to be the same protocol as port 445, not port 139. Since it probably isn't possible to change Windows' ports normally, this is mostly useful if you're bouncing through a relay or something.

smbsign: Controls whether or not server signatures are checked in SMB packets. By default, on Windows, server signatures aren't enabled or required. By default, this library will always sign packets if it knows how, and will check signatures if the server says to. Possible values are:

  • 'force': Always check server signatures, even if server says it doesn't support them (will probably fail, but is technically more secure).

  • 'negotiate': [default] Use signatures if server supports them.

  • 'ignore': Never check server signatures. Not recommended.

  • 'disable': Don't send signatures, at all, and don't check the server's. not recommended. More information on signatures can be found in 'smbauth.lua'.

randomseed: Set to a value to change the filenames/service names that are randomly generated.

                                        
                                            ###############################################################################
# OpenVAS Vulnerability Test
# $Id: gb_nmap_smb_os_discovery_net.nasl 5499 2017-03-06 13:06:09Z teissa $
#
# Autogenerated NSE wrapper
#
# Authors:
# NSE-Script: Ron Bowes
# NASL-Wrapper: autogenerated
#
# Copyright:
# NSE-Script: The Nmap Security Scanner (http://nmap.org)
# Copyright (C) 2011 Greenbone Networks GmbH, http://www.greenbone.net
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License version 2
# (or any later version), as published by the Free Software Foundation.
#
# 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 = "Attempts to determine the operating system, computer name, domain, and current time over the SMB
protocol (ports 445 or 139). This is done by starting a session with the anonymous  account (or with
a proper user account, if one is given; it likely doesn't make a difference); in response to a
session starting, the server will send back all this information.

Some systems, like Samba, will blank out their name (and only send their domain).  Other systems
(like embedded printers) will simply leave out the information. Other systems will blank out various
pieces (some will send back 0 for the current time, for example).

Retrieving the name and operating system of a server is a vital step in targeting an attack against
it, and this script makes that retrieval easy. Additionally, if a penetration tester is choosing
between multiple targets, the time can help identify servers that are being poorly maintained (for
more information/random thoughts on using the time, see http://www.skullsecurity.org/blog/?p=76.

Although the standard 'smb*' script arguments can be used,  they likely won't change the
outcome in any meaningful way.


SYNTAX:

smbbasic:     Forces the authentication to use basic security, as opposed to 'extended security'. 
Against most modern systems, extended security should work, but there may be cases
where you want to force basic. There's a chance that you'll get better results for 
enumerating users if you turn on basic authentication. 


smbport:       Override the default port choice. If 'smbport' is open, it's used. It's assumed
to be the same protocol as port 445, not port 139. Since it probably isn't possible to change
Windows' ports normally, this is mostly useful if you're bouncing through a relay or something. 


smbsign:       Controls whether or not server signatures are checked in SMB packets. By default, on Windows,
server signatures aren't enabled or required. By default, this library will always sign 
packets if it knows how, and will check signatures if the server says to. Possible values are:

- 'force':      Always check server signatures, even if server says it doesn't support them (will 
probably fail, but is technically more secure). 

- 'negotiate': [default] Use signatures if server supports them. 

- 'ignore':    Never check server signatures. Not recommended. 

- 'disable':   Don't send signatures, at all, and don't check the server's. not recommended. 
More information on signatures can be found in 'smbauth.lua'.


randomseed:    Set to a value to change the filenames/service names that are randomly generated.";

if(description)
{
    script_id(104028);
    script_version("$Revision: 5499 $");
    script_tag(name:"last_modification", value:"$Date: 2017-03-06 14:06:09 +0100 (Mon, 06 Mar 2017) $");
    script_tag(name:"creation_date", value:"2011-06-01 16:32:46 +0200 (Wed, 01 Jun 2011)");
    script_tag(name:"cvss_base", value:"0.0");
    script_tag(name:"cvss_base_vector", value:"AV:N/AC:L/Au:N/C:N/I:N/A:N");
    script_name("Nmap NSE net: smb-os-discovery");


    script_category(ACT_INIT);
    script_tag(name:"qod_type", value:"remote_analysis");
    script_copyright("NSE-Script: The Nmap Security Scanner; NASL-Wrapper: Greenbone Networks GmbH");
    script_family("Nmap NSE net");
    script_dependencies("nmap_nse_net.nasl");
    script_mandatory_keys("Tools/Launch/nmap_nse_net");

    script_add_preference(name:"smbbasic", value:"", type:"entry");
    script_add_preference(name:"smbport", value:"", type:"entry");
    script_add_preference(name:"smbsign", value:"", type:"entry");
    script_add_preference(name:"randomseed", value:"", type:"entry");

    script_tag(name : "summary" , value : tag_summary);
    exit(0);
}


include("nmap.inc");


phase = 0;
if (defined_func("scan_phase")) {
    phase = scan_phase();
}

if (phase == 1) {
    # Get the preferences
    argv = make_array();

    pref = script_get_preference("smbbasic");
    if (!isnull(pref) && pref != "") {
        argv["smbbasic"] = string('"', pref, '"');
    }
    pref = script_get_preference("smbport");
    if (!isnull(pref) && pref != "") {
        argv["smbport"] = string('"', pref, '"');
    }
    pref = script_get_preference("smbsign");
    if (!isnull(pref) && pref != "") {
        argv["smbsign"] = string('"', pref, '"');
    }
    pref = script_get_preference("randomseed");
    if (!isnull(pref) && pref != "") {
        argv["randomseed"] = string('"', pref, '"');
    }
    nmap_nse_register(script:"smb-os-discovery", args:argv);
} else if (phase == 2) {
    res = nmap_nse_get_results(script:"smb-os-discovery");
    foreach portspec (keys(res)) {
        output_banner = 'Result found by Nmap Security Scanner (smb-os-discovery.nse) http://nmap.org:\n\n';
        if (portspec == "0") {
            log_message(data:output_banner + res[portspec], port:0);
        } else {
            v = split(portspec, sep:"/", keep:0);
            proto = v[0];
            port = v[1];
            log_message(data:output_banner + res[portspec], port:port, protocol:proto);
        }
    }
}