Nmap NSE net: dns-cache-snoop

2011-06-01T00:00:00
ID OPENVAS:104033
Type openvas
Reporter NSE-Script: The Nmap Security Scanner; NASL-Wrapper: Greenbone Networks GmbH
Modified 2017-03-07T00:00:00

Description

Performs DNS cache snooping against a DNS server.

There are two modes of operation, controlled by the 'dns-cache-snoop.mode' script argument. In 'nonrecursive' mode (the default), queries are sent to the server with the RD (recursion desired) flag set to 0. The server should respond positively to these only if it has the domain cached. In 'timed' mode, the mean and standard deviation response times for a cached domain are calculated by sampling the resolution of a name (www.google.com) several times. Then, each domain is resolved and the time taken compared to the mean. If it is less than one standard deviation over the mean, it is considered cached. The 'timed' mode inserts entries in the cache and can only be used reliably once.

The default list of domains to check consists of the top 50 most popular sites, each site being listed twice, once with 'www.' and once without. Use the 'dns-cache-snoop.domains' script argument to use a different list.

SYNTAX:

dns-cache-snoop.domains: an array of domain to check in place of the default list.

dns-cache-snoop.mode: which of two supported snooping methods to use. 'nonrecursive', the default, checks if the server returns results for non-recursive queries. Some servers may disable this. 'timed' measures the difference in time taken to resolve cached and non-cached hosts. This mode will pollute the DNS cache and can only be used once reliably.

                                        
                                            ###############################################################################
# OpenVAS Vulnerability Test
# $Id: gb_nmap_dns_cache_snoop_net.nasl 5505 2017-03-07 10:00:18Z teissa $
#
# Autogenerated NSE wrapper
#
# Authors:
# NSE-Script: Eugene V. Alexeev
# 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 = "Performs DNS cache snooping against a DNS server.

There are two modes of operation, controlled by the 'dns-cache-snoop.mode' script
argument. In 'nonrecursive' mode (the default), queries are sent to the server with the
RD (recursion desired) flag set to 0. The server should respond positively to these only if it has
the domain cached. In 'timed' mode, the mean and standard deviation response times for a
cached domain are calculated by sampling the resolution of a name (www.google.com) several times.
Then, each domain is resolved and the time taken compared to the mean. If it is less than one
standard deviation over the mean, it is considered cached. The 'timed' mode inserts
entries in the cache and can only be used reliably once.

The default list of domains to check consists of the top 50 most popular sites, each site being
listed twice, once with 'www.' and once without. Use the 'dns-cache-snoop.domains' script
argument to use a different list.


SYNTAX:

dns-cache-snoop.domains:  an array of domain to check in place of
the default list.



dns-cache-snoop.mode:  which of two supported snooping methods to
use. 'nonrecursive', the default, checks if the server
returns results for non-recursive queries. Some servers may disable
this. 'timed' measures the difference in time taken to
resolve cached and non-cached hosts. This mode will pollute the DNS
cache and can only be used once reliably.";

if(description)
{
    script_id(104033);
    script_version("$Revision: 5505 $");
    script_tag(name:"last_modification", value:"$Date: 2017-03-07 11:00:18 +0100 (Tue, 07 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:"5.0");
    script_tag(name:"cvss_base_vector", value:"AV:N/AC:L/Au:N/C:P/I:N/A:N");
    script_name("Nmap NSE net: dns-cache-snoop");


    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:"dns-cache-snoop.domains", value:"", type:"entry");
    script_add_preference(name:"dns-cache-snoop.mode", value:"", type:"entry");

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


include("nmap.inc");

# The corresponding NSE script does't belong to the 'safe' category
if (safe_checks()) exit(0);

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

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

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