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| -rw-r--r-- | scripts/smb-enum-sessions.nse | 328 |
1 files changed, 328 insertions, 0 deletions
diff --git a/scripts/smb-enum-sessions.nse b/scripts/smb-enum-sessions.nse new file mode 100644 index 0000000..495c583 --- /dev/null +++ b/scripts/smb-enum-sessions.nse @@ -0,0 +1,328 @@ +local datetime = require "datetime" +local msrpc = require "msrpc" +local smb = require "smb" +local stdnse = require "stdnse" +local string = require "string" +local table = require "table" + +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] +-- +-- @see smb-enum-users.nse + +author = "Ron Bowes" +copyright = "Ron Bowes" +license = "Same as Nmap--See https://nmap.org/book/man-legal.html" +categories = {"discovery","intrusive"} +dependencies = {"smb-brute"} + + +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.debug3("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.debug3("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 + + +action = function(host) + + 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]" + else + time = datetime.format_time(time) + end + + local idle_time = sessions[i]['idle_time'] + if(idle_time == 0) then + idle_time = "[not idle]" + else + idle_time = datetime.format_time(idle_time) + 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 + + + |