local bin = require "bin" local bit = require "bit" local ipOps = require "ipOps" local math = require "math" local nmap = require "nmap" local os = require "os" local smb = require "smb" local stdnse = require "stdnse" local string = require "string" local table = require "table" description = [[ Checks if a host is infected with Conficker.C or higher, based on Conficker's peer to peer communication. When Conficker.C or higher infects a system, it opens four ports: two TCP and two UDP. The ports are random, but are seeded with the current week and the IP of the infected host. By determining the algorithm, one can check if these four ports are open, and can probe them for more data. Once the open ports are found, communication can be initiated using Conficker's custom peer to peer protocol. If a valid response is received, then a valid Conficker infection has been found. This check won't work properly on a multihomed or NATed system because the open ports will be based on a nonpublic IP. The argument checkall tells Nmap to attempt communication with every open port (much like a version check) and the argument realip tells Nmap to base its port generation on the given IP address instead of the actual IP. By default, this will run against a system that has a standard Windows port open (445, 139, 137). The arguments checkall and checkconficker will both perform checks regardless of which port is open, see the args section for more information. Note: Ensure your clock is correct (within a week) before using this script! The majority of research for this script was done by Symantec Security Response, and some was taken from public sources (most notably the port blacklisting was found by David Fifield). A big thanks goes out to everybody who contributed! ]] --- -- @args checkall If set to 1 or true, attempt -- to communicate with every open port. -- @args checkconficker If set to 1 or true, the script will always run on active hosts, -- it doesn't matter if any open ports were detected. -- @args realip An IP address to use in place of the one known by Nmap. -- -- @usage -- # Run the scripts against host(s) that appear to be Windows -- nmap --script p2p-conficker,smb-os-discovery,smb-check-vulns --script-args=safe=1 -T4 -vv -p445 -- sudo nmap -sU -sS --script p2p-conficker,smb-os-discovery,smb-check-vulns --script-args=safe=1 -vv -T4 -p U:137,T:139 -- -- # Run the scripts against all active hosts (recommended) -- nmap -p139,445 -vv --script p2p-conficker,smb-os-discovery,smb-check-vulns --script-args=checkconficker=1,safe=1 -T4 -- -- # Run scripts against all 65535 ports (slow) -- nmap --script p2p-conficker,smb-os-discovery,smb-check-vulns -p- --script-args=checkall=1,safe=1 -vv -T4 -- -- # Base checks on a different ip address (NATed) -- nmap --script p2p-conficker,smb-os-discovery -p445 --script-args=realip=\"192.168.1.65\" -vv -T4 -- -- @output -- Clean machine (results printed only if extra verbosity ("-vv")is specified): -- Host script results: -- | p2p-conficker: Checking for Conficker.C or higher... -- | | Check 1 (port 44329/tcp): CLEAN (Couldn't connect) -- | | Check 2 (port 33824/tcp): CLEAN (Couldn't connect) -- | | Check 3 (port 31380/udp): CLEAN (Failed to receive data) -- | | Check 4 (port 52600/udp): CLEAN (Failed to receive data) -- |_ |_ 0/4 checks: Host is CLEAN or ports are blocked -- -- Infected machine (results always printed): -- Host script results: -- | p2p-conficker: Checking for Conficker.C or higher... -- | | Check 1 (port 18707/tcp): INFECTED (Received valid data) -- | | Check 2 (port 65273/tcp): INFECTED (Received valid data) -- | | Check 3 (port 11722/udp): INFECTED (Received valid data) -- | | Check 4 (port 12690/udp): INFECTED (Received valid data) -- |_ |_ 4/4 checks: Host is likely INFECTED -- ----------------------------------------------------------------------- author = "Ron Bowes (with research from Symantec Security Response)" copyright = "Ron Bowes" license = "Same as Nmap--See http://nmap.org/book/man-legal.html" categories = {"default","safe"} -- Max packet size local MAX_PACKET = 0x2000 -- Flags local mode_flags = { FLAG_MODE = bit.lshift(1, 0), FLAG_LOCAL_ACK = bit.lshift(1, 1), FLAG_IS_TCP = bit.lshift(1, 2), FLAG_IP_INCLUDED = bit.lshift(1, 3), FLAG_UNKNOWN0_INCLUDED = bit.lshift(1, 4), FLAG_UNKNOWN1_INCLUDED = bit.lshift(1, 5), FLAG_DATA_INCLUDED = bit.lshift(1, 6), FLAG_SYSINFO_INCLUDED = bit.lshift(1, 7), FLAG_ENCODED = bit.lshift(1, 15) } ---For a hostrule, simply use the 'smb' ports as an indicator, unless the user overrides it hostrule = function(host) if(smb.get_port(host) ~= nil) then return true elseif(nmap.registry.args.checkall == "true" or nmap.registry.args.checkall == "1") then return true elseif(nmap.registry.args.checkconficker == "true" or nmap.registry.args.checkconficker == "1") then return true end return false end -- Multiply two 32-bit integers and return a 64-bit product. The first return -- value is the low-order 32 bits of the product and the second return value is -- the high-order 32 bits. -- --@param u First number (0 <= u <= 0xFFFFFFFF) --@param v Second number (0 <= v <= 0xFFFFFFFF) --@return 64-bit product of u*v, as a pair of 32-bit integers. local function mul64(u, v) -- This is based on formula (2) from section 4.3.3 of The Art of -- Computer Programming. We split u and v into upper and lower 16-bit -- chunks, such that -- u = 2**16 u1 + u0 and v = 2**16 v1 + v0 -- Then -- u v = (2**16 u1 + u0) * (2**16 v1 + v0) -- = 2**32 u1 v1 + 2**16 (u0 v1 + u1 v0) + u0 v0 assert(0 <= u and u <= 0xFFFFFFFF) assert(0 <= v and v <= 0xFFFFFFFF) local u0, u1 = bit.band(u, 0xFFFF), bit.rshift(u, 16) local v0, v1 = bit.band(v, 0xFFFF), bit.rshift(v, 16) -- t uses at most 49 bits, which is within the range of exact integer -- precision of a Lua number. local t = u0 * v0 + (u0 * v1 + u1 * v0) * 65536 return bit.band(t, 0xFFFFFFFF), u1 * v1 + bit.rshift(t, 32) end ---Rotates the 64-bit integer defined by h:l left by one bit. -- --@param h The high-order 32 bits --@param l The low-order 32 bits --@return 64-bit rotated integer, as a pair of 32-bit integers. local function rot64(h, l) local i assert(0 <= h and h <= 0xFFFFFFFF) assert(0 <= l and l <= 0xFFFFFFFF) local tmp = bit.band(h, 0x80000000) -- tmp = h & 0x80000000 h = bit.lshift(h, 1) -- h = h << 1 h = bit.bor(h, bit.rshift(l, 31)) -- h = h | (l >> 31) l = bit.lshift(l, 1) if(tmp ~= 0) then l = bit.bor(l, 1) end h = bit.band(h, 0xFFFFFFFF) l = bit.band(l, 0xFFFFFFFF) return h, l end ---Check if a port is Blacklisted. Thanks to David Fifield for determining the purpose of the "magic" -- array: -- -- -- Basically, each bit in the blacklist array represents a group of 32 ports. If that bit is on, those ports -- are blacklisted and will never come up. -- --@param port The port to check --@return true if the port is blacklisted, false otherwise local function is_blacklisted_port(port) local r, l local blacklist = { 0xFFFFFFFF, 0xFFFFFFFF, 0xF0F6BFBB, 0xBB5A5FF3, 0xF3977011, 0xEB67BFBF, 0x5F9BFAC8, 0x34D88091, 0x1E2282DF, 0x573402C4, 0xC0000084, 0x03000209, 0x01600002, 0x00005000, 0x801000C0, 0x00500040, 0x000000A1, 0x01000000, 0x01000000, 0x00022A20, 0x00000080, 0x04000000, 0x40020000, 0x88000000, 0x00000180, 0x00081000, 0x08801900, 0x00800B81, 0x00000280, 0x080002C0, 0x00A80000, 0x00008000, 0x00100040, 0x00100000, 0x00000000, 0x00000000, 0x10000008, 0x00000000, 0x00000000, 0x00000004, 0x00000002, 0x00000000, 0x00040000, 0x00000000, 0x00000000, 0x00000000, 0x00410000, 0x82000000, 0x00000000, 0x00000000, 0x00000001, 0x00000000, 0x00000000, 0x00000000, 0x00000000, 0x00000000, 0x00000000, 0x00000000, 0x00000000, 0x00000000, 0x00000000, 0x00000000, 0x00000008, 0x80000000, }; r = bit.rshift(port, 5) l = bit.lshift(1, bit.band(r, 0x1f)) r = bit.rshift(r, 5) return (bit.band(blacklist[r + 1], l) ~= 0) end ---Generates the four random ports that Conficker uses, based on the current time and the IP address. -- --@param ip The IP address as a 32-bit little endian integer --@param seed The seed, based on the time (floor((time - 345600) / 604800)) --@return An array of four ports; the first and third are TCP, and the second and fourth are UDP. local function prng_generate_ports(ip, seed) local ports = {0, 0, 0, 0} local v1, v2 local port1, port2, shift1, shift2 local i local magic = 0x015A4E35 stdnse.print_debug(1, "Conficker: Generating ports based on ip (0x%08x) and seed (%d)", ip, seed) v1 = -(ip + 1) repeat -- Loop 10 times to generate the first pair of ports for i = 0, 9, 1 do v1, v2 = mul64(bit.band(v1, 0xFFFFFFFF), bit.band(magic, 0xFFFFFFFF)) -- Add 1 to v1, handling overflows if(v1 ~= 0xFFFFFFFF) then v1 = v1 + 1 else v1 = 0 v2 = v2 + 1 end v2 = bit.rshift(v2, i) ports[(i % 2) + 1] = bit.bxor(bit.band(v2, 0xFFFF), ports[(i % 2) + 1]) end until(is_blacklisted_port(ports[1]) == false and is_blacklisted_port(ports[2]) == false and ports[1] ~= ports[2]) -- Update the accumlator with the seed v1 = bit.bxor(v1, seed) -- Loop 10 more times to generate the second pair of ports repeat for i = 0, 9, 1 do v1, v2 = mul64(bit.band(v1, 0xFFFFFFFF), bit.band(magic, 0xFFFFFFFF)) -- Add 1 to v1, handling overflows if(v1 ~= 0xFFFFFFFF) then v1 = v1 + 1 else v1 = 0 v2 = v2 + 1 end v2 = bit.rshift(v2, i) ports[(i % 2) + 3] = bit.bxor(bit.band(v2, 0xFFFF), ports[(i % 2) + 3]) end until(is_blacklisted_port(ports[3]) == false and is_blacklisted_port(ports[4]) == false and ports[3] ~= ports[4]) return {ports[1], ports[2], ports[3], ports[4]} end ---Calculate a checksum for the data. This checksum is appended to every Conficker packet before the random noise. -- The checksum includes the key and data, but not the noise and optional length. -- --@param data The data to create a checksum for. --@return An integer representing the checksum. local function p2p_checksum(data) local pos, i local hash = #data stdnse.print_debug(2, "Conficker: Calculating checksum for %d-byte buffer", #data) -- Get the first character pos, i = bin.unpack(" 0xFFFFFFFF) then -- Handle overflows key2 = key2 + (bit.rshift(key1, 32)) key2 = bit.band(key2, 0xFFFFFFFF) key1 = bit.band(key1, 0xFFFFFFFF) end end return buf end ---Decrypt the packet, verify it, and parse it. This function will fail with an error if the packet can't be -- parsed properly (likely means the port is being used for something else), but will return successfully -- without checking the packet's checksum (although it does calculate the checksum). It's up to the calling -- function to decide if it cares about the checksum. -- --@param packet The packet, without the optional length (if it's TCP). --@return (status, result) If status is true, result is a table (including 'hash' and 'real_hash'). If status -- is false, result is a string that indicates why the parse failed. function p2p_parse(packet) local pos = 1 local data = {} -- Get the key pos, data['key1'], data['key2'] = bin.unpack("prng_generate_ports, or from unidentified ports) --@return (status, reason, data) Status indicates whether or not Conficker is suspected to be present (truefalse = no Conficker). If status is true, data is the table of information returned by -- Conficker. local function conficker_check(ip, port, protocol) local status, packet local socket local response status, packet = p2p_create_packet(protocol) if(status == false) then return false, packet end -- Try to connect to the first socket socket = nmap.new_socket() socket:set_timeout(5000) status, response = socket:connect(ip, port, protocol) if(status == false) then return false, "Couldn't establish connection (" .. response .. ")" end -- Send the packet socket:send(packet) -- Read a response (2 bytes minimum, because that's the TCP length) status, response = socket:receive_bytes(2) if(status == false) then return false, "Couldn't receive bytes: " .. response elseif(response == "ERROR") then return false, "Failed to receive data" elseif(response == "TIMEOUT") then return false, "Timeout" elseif(response == "EOF") then return false, "Couldn't connect" end -- If it's TCP, get the length and make sure we have the full packet if(protocol == "tcp") then local length _, length = bin.unpack(" (#response - 2) do local response2 status, response2 = socket:receive_bytes(2) if(status == false) then return false, "Couldn't receive bytes: " .. response2 elseif(response2 == "ERROR") then return false, "Failed to receive data" elseif(response2 == "TIMEOUT") then return false, "Timeout" elseif(response2 == "EOF") then return false, "Couldn't connect" end response = response .. response2 end -- Remove the 'length' bytes response = string.sub(response, 3) end -- Close the socket socket:close() local status, result = p2p_parse(response) if(status == false) then return false, "Data received, but wasn't Conficker data: " .. result end if(result['hash'] ~= result['real_hash']) then return false, "Data received, but checksum was invalid (possibly INFECTED)" end return true, "Received valid data", result end action = function(host) local tcp_ports = {} local udp_ports = {} local response = {} local i local port, protocol local count = 0 local checks = 0 -- Generate a complete list of valid ports if(nmap.registry.args.checkall == "true" or nmap.registry.args.checkall == "1") then for i = 1, 65535, 1 do if(not(is_blacklisted_port(i))) then local tcp = nmap.get_port_state(host, {number=i, protocol="tcp"}) if(tcp ~= nil and tcp.state == "open") then tcp_ports[i] = true end local udp = nmap.get_port_state(host, {number=i, protocol="udp"}) if(udp ~= nil and (udp.state == "open" or udp.state == "open|filtered")) then udp_ports[i] = true end end end end -- Generate ports based on the ip and time local seed = math.floor((os.time() - 345600) / 604800) local ip = host.ip -- Use the provided IP, if it exists if(nmap.registry.args.realip ~= nil) then ip = nmap.registry.args.realip end -- Reverse the IP's endianness ip = ipOps.todword(ip) ip = bin.pack(">I", ip) _, ip = bin.unpack(" 1) then table.insert(response, string.format("%d/%d checks are positive: Host is CLEAN or ports are blocked", count, checks)) else response = '' end else table.insert(response, string.format("%d/%d checks are positive: Host is likely INFECTED", count, checks)) end return stdnse.format_output(true, response) end