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description = [[
Enumerates the users logged into a system either locally or through an SMB share. The local users
can be logged on either physically on the machine, or through a terminal services session.
Connections to a SMB share are, for example, people connected to fileshares or making RPC calls.
Nmap's connection will also show up, and is generally identified by the one that connected "0
seconds ago".
From the perspective of a penetration tester, the SMB Sessions is probably the most useful
part of this program, especially because it doesn't require a high level of access. On, for
example, a file server, there might be a dozen or more users connected at the same time. Based
on the usernames, it might tell the tester what types of files are stored on the share.
Since the IP they're connected from and the account is revealed, the information here can also
provide extra targets to test, as well as a username that's likely valid on that target. Additionally,
since a strong username to ip correlation is given, it can be a boost to a social engineering
attack.
Enumerating the logged in users is done by reading the remote registry (and therefore won't
work against Vista, which disables it by default). Keys stored under <code>HKEY_USERS</code> are
SIDs that represent the connected users, and those SIDs can be converted to proper names by using
the <code>lsar.LsaLookupSids</code> function. Doing this requires any access higher than
anonymous; guests, users, or administrators are all able to perform this request on Windows 2000,
XP, 2003, and Vista.
Enumerating SMB connections is done using the <code>srvsvc.netsessenum</code> function, which
returns the usernames that are logged in, when they logged in, and how long they've been idle
for. The level of access required for this varies between Windows versions, but in Windows
2000 anybody (including the anonymous account) can access this, and in Windows 2003 a user
or administrator account is required.
I learned the idea and technique for this from Sysinternals' tool, <code>PsLoggedOn.exe</code>. I (Ron
Bowes) use similar function calls to what they use (although I didn't use their source),
so thanks go out to them. Thanks also to Matt Gardenghi, for requesting this script.
WARNING: I have experienced crashes in regsvc.exe while making registry calls
against a fully patched Windows 2000 system; I've fixed the issue that caused it,
but there's no guarantee that it (or a similar vuln in the same code) won't show
up again. Since the process automatically restarts, it doesn't negatively impact
the system, besides showing a message box to the user.
]]
---
--@usage
-- nmap --script smb-enum-sessions.nse -p445 <host>
-- sudo nmap -sU -sS --script smb-enum-sessions.nse -p U:137,T:139 <host>
--
--@output
-- Host script results:
-- | smb-enum-sessions:
-- | Users logged in:
-- | | TESTBOX\Administrator since 2008-10-21 08:17:14
-- | |_ DOMAIN\rbowes since 2008-10-20 09:03:23
-- | Active SMB Sessions:
-- |_ |_ ADMINISTRATOR is connected from 10.100.254.138 for [just logged in, it's probably you], idle for [not idle]
-----------------------------------------------------------------------
author = "Ron Bowes"
copyright = "Ron Bowes"
license = "Same as Nmap--See http://nmap.org/book/man-legal.html"
categories = {"discovery","intrusive"}
dependencies = {"smb-brute"}
require 'msrpc'
require 'smb'
require 'stdnse'
hostrule = function(host)
return smb.get_port(host) ~= nil
end
---Attempts to enumerate the sessions on a remote system using MSRPC calls. This will likely fail
-- against a modern system, but will succeed against Windows 2000.
--
--@param host The host object.
--@return Status (true or false).
--@return List of sessions (if status is true) or an an error string (if status is false).
local function srvsvc_enum_sessions(host)
local i
local status, smbstate
local bind_result, netsessenum_result
-- Create the SMB session
status, smbstate = msrpc.start_smb(host, msrpc.SRVSVC_PATH)
if(status == false) then
return false, smbstate
end
-- Bind to SRVSVC service
status, bind_result = msrpc.bind(smbstate, msrpc.SRVSVC_UUID, msrpc.SRVSVC_VERSION, nil)
if(status == false) then
msrpc.stop_smb(smbstate)
return false, bind_result
end
-- Call netsessenum
status, netsessenum_result = msrpc.srvsvc_netsessenum(smbstate, host.ip)
if(status == false) then
msrpc.stop_smb(smbstate)
return false, netsessenum_result
end
-- Stop the SMB session
msrpc.stop_smb(smbstate)
return true, netsessenum_result['ctr']['array']
end
---Enumerates the users logged in locally (or through terminal services) by using functions
-- that access the registry. To perform this check, guest access or higher is required.
--
-- The way this works is based on the registry. HKEY_USERS is enumerated, and every key in it
-- that looks like a SID is converted to a username using the LSA lookup function lsa_lookupsids2().
--
--@param host The host object.
--@return An array of user tables, each with the keys <code>name</code>, <code>domain</code>, and <code>changed_date</code> (representing
-- when they logged in).
local function winreg_enum_rids(host)
local i, j
local elements = {}
-- Create the SMB session
local status, smbstate = msrpc.start_smb(host, msrpc.WINREG_PATH)
if(status == false) then
return false, smbstate
end
-- Bind to WINREG service
local status, bind_result = msrpc.bind(smbstate, msrpc.WINREG_UUID, msrpc.WINREG_VERSION, nil)
if(status == false) then
msrpc.stop_smb(smbstate)
return false, bind_result
end
local status, openhku_result = msrpc.winreg_openhku(smbstate)
if(status == false) then
msrpc.stop_smb(smbstate)
return false, openhku_result
end
-- Loop through the keys under HKEY_USERS and grab the names
i = 0
repeat
local status, enumkey_result = msrpc.winreg_enumkey(smbstate, openhku_result['handle'], i, "")
if(status == true) then
local status, openkey_result
local element = {}
element['name'] = enumkey_result['name']
-- To get the time the user logged in, we check the 'Volatile Environment' key
-- This can fail with the 'guest' account due to access restrictions
local status, openkey_result = msrpc.winreg_openkey(smbstate, openhku_result['handle'], element['name'] .. "\\Volatile Environment")
if(status ~= false) then
local queryinfokey_result, closekey_result
-- Query the info about this key. The response will tell us when the user logged into the server.
local status, queryinfokey_result = msrpc.winreg_queryinfokey(smbstate, openkey_result['handle'])
if(status == false) then
msrpc.stop_smb(smbstate)
return false, queryinfokey_result
end
local status, closekey_result = msrpc.winreg_closekey(smbstate, openkey_result['handle'])
if(status == false) then
msrpc.stop_smb(smbstate)
return false, closekey_result
end
element['changed_date'] = queryinfokey_result['last_changed_date']
else
-- Getting extra details failed, but we can still handle this
element['changed_date'] = "<unknown>"
end
elements[#elements + 1] = element
end
i = i + 1
until status ~= true
local status, closekey_result = msrpc.winreg_closekey(smbstate, openhku_result['handle'])
if(status == false) then
msrpc.stop_smb(smbstate)
return false, closekey_result
end
msrpc.stop_smb(smbstate)
-- Start a new SMB session
local status, smbstate = msrpc.start_smb(host, msrpc.LSA_PATH)
if(status == false) then
return false, smbstate
end
-- Bind to LSA service
local status, bind_result = msrpc.bind(smbstate, msrpc.LSA_UUID, msrpc.LSA_VERSION, nil)
if(status == false) then
msrpc.stop_smb(smbstate)
return false, bind_result
end
-- Get a policy handle
local status, openpolicy2_result = msrpc.lsa_openpolicy2(smbstate, host.ip)
if(status == false) then
msrpc.stop_smb(smbstate)
return false, openpolicy2_result
end
-- Convert the SID to the name of the user
local results = {}
stdnse.print_debug(3, "MSRPC: Found %d SIDs that might be logged in", #elements)
for i = 1, #elements, 1 do
if(elements[i]['name'] ~= nil) then
local sid = elements[i]['name']
if(string.find(sid, "^S-") ~= nil and string.find(sid, "-%d+$") ~= nil) then
-- The rid is the last digits before the end of the string
local rid = string.sub(sid, string.find(sid, "%d+$"))
local status, lookupsids2_result = msrpc.lsa_lookupsids2(smbstate, openpolicy2_result['policy_handle'], {elements[i]['name']})
if(status == false) then
-- It may not succeed, if it doesn't that's ok
stdnse.print_debug(3, "MSRPC: Lookup failed")
else
-- Create the result array
local result = {}
result['changed_date'] = elements[i]['changed_date']
result['rid'] = rid
-- Fill in the result from the response
if(lookupsids2_result['names']['names'][1] == nil) then
result['name'] = "<unknown>"
result['type'] = "<unknown>"
result['domain'] = ""
else
result['name'] = lookupsids2_result['names']['names'][1]['name']
result['type'] = lookupsids2_result['names']['names'][1]['sid_type']
if(lookupsids2_result['domains'] ~= nil and lookupsids2_result['domains']['domains'] ~= nil and lookupsids2_result['domains']['domains'][1] ~= nil) then
result['domain'] = lookupsids2_result['domains']['domains'][1]['name']
else
result['domain'] = ""
end
end
if(result['type'] ~= "SID_NAME_WKN_GRP") then -- Don't show "well known" accounts
-- Add it to the results
results[#results + 1] = result
end
end
end
end
end
-- Close the policy
msrpc.lsa_close(smbstate, openpolicy2_result['policy_handle'])
-- Stop the session
msrpc.stop_smb(smbstate)
return true, results
end
--_G.TRACEBACK = TRACEBACK or {}
action = function(host)
-- TRACEBACK[coroutine.running()] = true;
local response = {}
-- Enumerate the logged in users
local logged_in = {}
local status1, users = winreg_enum_rids(host)
if(status1 == false) then
logged_in['warning'] = "Couldn't enumerate login sessions: " .. users
else
logged_in['name'] = "Users logged in"
if(#users == 0) then
table.insert(response, "<nobody>")
else
for i = 1, #users, 1 do
if(users[i]['name'] ~= nil) then
table.insert(logged_in, string.format("%s\\%s since %s", users[i]['domain'], users[i]['name'], users[i]['changed_date']))
end
end
end
end
table.insert(response, logged_in)
-- Get the connected sessions
local sessions_output = {}
local status2, sessions = srvsvc_enum_sessions(host)
if(status2 == false) then
sessions_output['warning'] = "Couldn't enumerate SMB sessions: " .. sessions
else
sessions_output['name'] = "Active SMB sessions"
if(#sessions == 0) then
table.insert(sessions_output, "<none>")
else
-- Format the result
for i = 1, #sessions, 1 do
local time = sessions[i]['time']
if(time == 0) then
time = "[just logged in, it's probably you]"
elseif(time > 60 * 60 * 24) then
time = string.format("%dd%dh%02dm%02ds", time / (60*60*24), (time % (60*60*24)) / 3600, (time % 3600) / 60, time % 60)
elseif(time > 60 * 60) then
time = string.format("%dh%02dm%02ds", time / 3600, (time % 3600) / 60, time % 60)
else
time = string.format("%02dm%02ds", time / 60, time % 60)
end
local idle_time = sessions[i]['idle_time']
if(idle_time == 0) then
idle_time = "[not idle]"
elseif(idle_time > 60 * 60 * 24) then
idle_time = string.format("%dd%dh%02dm%02ds", idle_time / (60*60*24), (idle_time % (60*60*24)) / 3600, (idle_time % 3600) / 60, idle_time % 60)
elseif(idle_time > 60 * 60) then
idle_time = string.format("%dh%02dm%02ds", idle_time / 3600, (idle_time % 3600) / 60, idle_time % 60)
else
idle_time = string.format("%02dm%02ds", idle_time / 60, idle_time % 60)
end
table.insert(sessions_output, string.format("%s is connected from %s for %s, idle for %s", sessions[i]['user'], sessions[i]['client'], time, idle_time))
end
end
end
table.insert(response, sessions_output)
return stdnse.format_output(true, response)
end
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