9.8 High
CVSS3
Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
HIGH
Integrity Impact
HIGH
Availability Impact
HIGH
CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
10 High
CVSS2
Access Vector
NETWORK
Access Complexity
LOW
Authentication
NONE
Confidentiality Impact
COMPLETE
Integrity Impact
COMPLETE
Availability Impact
COMPLETE
AV:N/AC:L/Au:N/C:C/I:C/A:C
0.973 High
EPSS
Percentile
99.8%
This script enumerates information from remote Microsoft Telnet services with NTLM authentication enabled.
Sending a MS-TNAP NTLM authentication request with null credentials will cause the remote service to respond with a NTLMSSP message disclosing information to include NetBIOS, DNS, and OS build version.
See the documentation for the smbauth library.
nmap -p 23 --script telnet-ntlm-info <target>
23/tcp open telnet
| telnet-ntlm-info:
| Target_Name: ACTIVETELNET
| NetBIOS_Domain_Name: ACTIVETELNET
| NetBIOS_Computer_Name: HOST-TEST2
| DNS_Domain_Name: somedomain.com
| DNS_Computer_Name: host-test2.somedomain.com
| DNS_Tree_Name: somedomain.com
|_ Product_Version: 5.1.2600
local datetime = require "datetime"
local os = require "os"
local comm = require "comm"
local shortport = require "shortport"
local stdnse = require "stdnse"
local smbauth = require "smbauth"
local string = require "string"
description = [[
This script enumerates information from remote Microsoft Telnet services with NTLM
authentication enabled.
Sending a MS-TNAP NTLM authentication request with null credentials will cause the
remote service to respond with a NTLMSSP message disclosing information to include
NetBIOS, DNS, and OS build version.
]]
---
-- @usage
-- nmap -p 23 --script telnet-ntlm-info <target>
--
-- @output
-- 23/tcp open telnet
-- | telnet-ntlm-info:
-- | Target_Name: ACTIVETELNET
-- | NetBIOS_Domain_Name: ACTIVETELNET
-- | NetBIOS_Computer_Name: HOST-TEST2
-- | DNS_Domain_Name: somedomain.com
-- | DNS_Computer_Name: host-test2.somedomain.com
-- | DNS_Tree_Name: somedomain.com
-- |_ Product_Version: 5.1.2600
--
--@xmloutput
-- <elem key="Target_Name">ACTIVETELNET</elem>
-- <elem key="NetBIOS_Domain_Name">ACTIVETELNET</elem>
-- <elem key="NetBIOS_Computer_Name">HOST-TEST2</elem>
-- <elem key="DNS_Domain_Name">somedomain.com</elem>
-- <elem key="DNS_Computer_Name">host-test2.somedomain.com</elem>
-- <elem key="DNS_Tree_Name">somedomain.com</elem>
-- <elem key="Product_Version">5.1.2600</elem>
author = "Justin Cacak"
license = "Same as Nmap--See https://nmap.org/book/man-legal.html"
categories = {"default", "discovery", "safe"}
local _, ntlm_auth_blob = smbauth.get_security_blob(
nil, nil, nil, nil, nil, nil, nil,
0x00000001 + -- Negotiate Unicode
0x00000002 + -- Negotiate OEM strings
0x00000004 + -- Request Target
0x00000200 + -- Negotiate NTLM
0x00008000 + -- Negotiate Always Sign
0x00080000 + -- Negotiate NTLM2 Key
0x20000000 + -- Negotiate 128
0x80000000 -- Negotiate 56
)
--
-- Create MS-TNAP Login Packet (Option Command IS)
-- Ref: http://msdn.microsoft.com/en-us/library/cc247789.aspx
local tnap_login_packet = string.pack("<BBBBBBB I4I4",
0xff, -- IAC
0xfa, -- Sub-option (250)
0x25, -- Subcommand: auth option
0x00, -- Auth Cmd: IS (0)
0x0f, -- Auth Type: NTLM (15)
0x00, -- Who: Mask client to server (0)
0x00, -- Command: NTLM_NEGOTIATE (0)
#ntlm_auth_blob, -- NTLM_DataSize (4 bytes, little-endian)
0x00000002) -- NTLM_BufferType (4 bytes, little-endian)
.. ntlm_auth_blob .. string.pack("<BB",
0xff, 0xf0) -- Sub-option End
portrule = shortport.port_or_service(23, "telnet")
action = function(host, port)
local output = stdnse.output_table()
local socket, response, early_resp = comm.opencon(host, port, tnap_login_packet, {recv_before=true})
if not socket then
return nil
end
local recvtime = os.time()
socket:close()
-- Continue only if NTLMSSP response is returned.
-- Verify that the response is terminated with Sub-option End values as various
-- non Microsoft telnet implementations support NTLM but do not return valid data.
local data = string.match(response, "(NTLMSSP.*)\xff\xf0")
if not data then
return nil
end
-- Leverage smbauth.get_host_info_from_security_blob() for decoding
local ntlm_decoded = smbauth.get_host_info_from_security_blob(data)
if ntlm_decoded.timestamp then
-- 64-bit number of 100ns clicks since 1/1/1601
local unixstamp = ntlm_decoded.timestamp // 10000000 - 11644473600
datetime.record_skew(host, unixstamp, recvtime)
end
-- Target Name will always be returned under any implementation
output.Target_Name = ntlm_decoded.target_realm
-- Display information returned & ignore responses with null values
if ntlm_decoded.netbios_domain_name and #ntlm_decoded.netbios_domain_name > 0 then
output.NetBIOS_Domain_Name = ntlm_decoded.netbios_domain_name
end
if ntlm_decoded.netbios_computer_name and #ntlm_decoded.netbios_computer_name > 0 then
output.NetBIOS_Computer_Name = ntlm_decoded.netbios_computer_name
end
if ntlm_decoded.dns_domain_name and #ntlm_decoded.dns_domain_name > 0 then
output.DNS_Domain_Name = ntlm_decoded.dns_domain_name
end
if ntlm_decoded.fqdn and #ntlm_decoded.fqdn > 0 then
output.DNS_Computer_Name = ntlm_decoded.fqdn
end
if ntlm_decoded.dns_forest_name and #ntlm_decoded.dns_forest_name > 0 then
output.DNS_Tree_Name = ntlm_decoded.dns_forest_name
end
if ntlm_decoded.os_major_version then
output.Product_Version = string.format("%d.%d.%d",
ntlm_decoded.os_major_version, ntlm_decoded.os_minor_version, ntlm_decoded.os_build)
end
return output
end
9.8 High
CVSS3
Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
HIGH
Integrity Impact
HIGH
Availability Impact
HIGH
CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
10 High
CVSS2
Access Vector
NETWORK
Access Complexity
LOW
Authentication
NONE
Confidentiality Impact
COMPLETE
Integrity Impact
COMPLETE
Availability Impact
COMPLETE
AV:N/AC:L/Au:N/C:C/I:C/A:C
0.973 High
EPSS
Percentile
99.8%