diff options
Diffstat (limited to 'nselib/smb2.lua')
| -rw-r--r-- | nselib/smb2.lua | 392 |
1 files changed, 392 insertions, 0 deletions
diff --git a/nselib/smb2.lua b/nselib/smb2.lua new file mode 100644 index 0000000..4b60d04 --- /dev/null +++ b/nselib/smb2.lua @@ -0,0 +1,392 @@ +--- +-- Implements the Server Message Block (SMB) protocol version 2 and 3. +-- +-- The implementation extends smb.lua to support SMB dialects 2.0.2, 2.1, 3.0, +-- 3.0.2 and 3.1.1. This is a work in progress and not all commands are +-- implemented yet. Features/functionality will be added as the scripts +-- get updated. I tried to be consistent with the current implementation of +-- smb.lua but some fields may have changed name or don't exist anymore. +-- +-- @author Paulino Calderon <paulino@calderonpale.com> +-- @copyright Same as Nmap--See https://nmap.org/book/man-legal.html +--- + +local datetime = require "datetime" +local string = require "string" +local stdnse = require "stdnse" +local table = require "table" +local tableaux = require "tableaux" +local match = require "match" + +_ENV = stdnse.module("smb2", stdnse.seeall) + +local TIMEOUT = 10000 +local command_codes = +{ + SMB2_COM_NEGOTIATE = 0x0000, + SMB2_COM_SESSION_SETUP = 0x0001, + SMB2_COM_LOGOFF = 0x0002, + SMB2_COM_TREE_CONNECT = 0x0003, + SMB2_COM_TREE_DISCONNECT = 0x0004, + SMB2_COM_CREATE = 0x0005, + SMB2_COM_CLOSE = 0x0006, + SMB2_COM_FLUSH = 0x0007, + SMB2_COM_READ = 0x0008, + SMB2_COM_WRITE = 0x0009, + SMB2_COM_LOCK = 0x000A, + SMB2_COM_IOCTL = 0x000B, + SMB2_COM_CANCEL = 0x000C, + SMB2_COM_ECHO = 0x000D, + SMB2_COM_QUERY_DIRECTORY = 0x000E, + SMB2_COM_CHANGE_NOTIFY = 0x000F, + SMB2_COM_QUERY_INFO = 0x0010, + SMB2_COM_SET_INFO = 0x0011, + SMB2_COM_OPLOCK_BREAK = 0x0012 +} +local command_names = tableaux.invert(command_codes) +local smb2_values = { + -- Security Mode + SMB2_NEGOTIATE_SIGNING_ENABLED = 0x0001, + SMB2_NEGOTIATE_SIGNING_REQUIRED = 0x0002, + -- Capabilities + SMB2_GLOBAL_CAP_DFS = 0x00000001, + SMB2_GLOBAL_CAP_LEASING = 0x00000002, + SMB2_GLOBAL_CAP_LARGE_MTU = 0x00000004, + SMB2_GLOBAL_CAP_MULTI_CHANNEL = 0x00000008, + SMB2_GLOBAL_CAP_PERSISTENT_HANDLES = 0x00000010, + SMB2_GLOBAL_CAP_DIRECTORY_LEASING = 0x00000020, + SMB2_GLOBAL_CAP_ENCRYPTION = 0x00000040, + -- Context Types + SMB2_ENCRYPTION_CAPABILITIES = 0x0002, + SMB2_PREAUTH_INTEGRITY_CAPABILITIES = 0x0001 +} +local smb2_values_codes = tableaux.invert(smb2_values) + +local smb2_dialects = {0x0202, 0x0210, 0x0300, 0x0302, 0x0311} +local smb2_dialect_names = {} +for _, d in ipairs(smb2_dialects) do + -- convert 0x0abc to "a.b.c" + local name = stdnse.tohex(d, {separator = ".", group = 1}) + -- trim trailing ".0" at sub-minor level + smb2_dialect_names[d] = name:find(".0", 4, true) and name:sub(1, 3) or name +end + +--- +-- Returns the list of supported SMB 2 dialects +-- https://docs.microsoft.com/en-us/openspecs/windows_protocols/ms-smb2/fac3655a-7eb5-4337-b0ab-244bbcd014e8 +-- @return list of 16-bit numerical revision codes (0x202, 0x210, ...) +--- +function dialects () + return tableaux.tcopy(smb2_dialects) +end + +--- +-- Converts a supported SMB 2 dialect code to dialect name +-- https://docs.microsoft.com/en-us/openspecs/windows_protocols/ms-smb2/fac3655a-7eb5-4337-b0ab-244bbcd014e8 +-- @param dialect SMB 2 dialect revision code +-- @return string representing the dialect (or nil). Example: 0x202 -> "2.0.2" +--- +function dialect_name (dialect) + return smb2_dialect_names[dialect] +end + +--- +-- Creates a SMB2 SYNC header packet. +-- +-- SMB2 Packet Header - SYNC: +-- * https://msdn.microsoft.com/en-us/library/cc246529.aspx +-- +-- @param smb The SMB object associated with the connection. +-- @param command The SMB2 command to execute. +-- @param overrides Overrides table. +-- @return header The encoded SMB2 SYNC header. +--- +function smb2_encode_header_sync(smb, command, overrides) + overrides = overrides or {} + + local sig = "\xFESMB" -- SMB2 packet + local structureSize = 64 -- SYNC header structure size + local flags = 0 -- TODO: Set flags that will work for all dialects + + -- Increase the message id + if smb['MessageId'] then + smb['MessageId'] = smb['MessageId'] + 1 + end + + -- Header structure + local header = string.pack("<c4 I2 I2 I4 I2 I2 I4 I4 I8 I4 I4 I8 c16", + sig, -- 4 bytes: ProtocolId + structureSize, -- 2 bytes: StructureSize. Must be 64. + (overrides['CreditCharge'] or 0), -- 2 bytes: CreditCharge. + (overrides['Status'] or 0), -- 4 bytes: (ChannelSequence/Reserved)/Status. + command, -- 2 bytes: Command. + (overrides['CreditR'] or 0), -- 2 bytes: CreditRequest/CreditResponse. + (overrides['Flags'] or flags), -- 4 bytes: Flags. TODO + (overrides['NextCommand'] or 0), -- 4 bytes: NextCommand. + (overrides['MessageId'] or smb['MessageId'] or 0), -- 8 bytes: MessageId. + (overrides['Reserved'] or 0), -- 4 bytes: Reserved. + (overrides['TreeId'] or smb['TreeId'] or 0), -- 4 bytes: TreeId. + (overrides['SessionId'] or smb['SessionId'] or 0), -- 8 bytes: SessionId. + (overrides['Signature'] or '1234567890123456') -- 16 bytes: Signature. + ) + + return header +end + +--- +-- Sends a SMB2 packet +-- @param smb The SMB object associated with the connection +-- @param header The header encoded with <code>smb_encode_sync_header</code>. +-- @param data The data. +-- @param overrides Overrides table. +-- @return Boolean Status. +-- @return An error message if status is false. +--- +function smb2_send(smb, header, data, overrides) + overrides = overrides or {} + local body = header .. data + local attempts = 5 + local status, err + + local out = string.pack(">s4", body) + repeat + attempts = attempts - 1 + stdnse.debug3("SMB: Sending SMB packet (len: %d, attempts remaining: %d)", #out, attempts) + status, err = smb['socket']:send(out) + until(status or (attempts == 0)) + + if(attempts == 0) then + stdnse.debug1("SMB: Sending packet failed after 5 tries! Giving up.") + end + + return status, err +end + +--- +-- Reads the next SMB2 packet from the socket, and parses it into the header and data. +-- Netbios handling based taken from smb.lua. +-- +-- @param smb The SMB object associated with the connection +-- @param read_data [optional] Return data section. Set to false if you only need the header. Default: true +-- @return (status, header, data) If status is true, the header, +-- and data are all the raw arrays of bytes. +-- If status is false, header contains an error message and data is undefined. +--- +function smb2_read(smb, read_data) + stdnse.debug3("SMB2: Receiving SMB2 packet") + + -- Receive the response -- we make sure to receive at least 4 bytes, the length of the NetBIOS length + smb['socket']:set_timeout(TIMEOUT) + + -- attempt to read the Netbios header + local status, netbios_data = smb['socket']:receive_buf(match.numbytes(4), true); + + -- Make sure the connection is still alive + if not status then + return false, "SMB2: Failed to receive bytes: " .. netbios_data + end + + -- The length of the packet is 4 bytes of big endian (for our purposes). + -- The NetBIOS header is 24 bits, big endian + local netbios_length, pos = string.unpack(">I4", netbios_data) + -- Make the length 24 bits + netbios_length = netbios_length & 0x00FFFFFF + + -- The total length is the netbios_length, plus 4 (for the length itself) + local length = netbios_length + 4 + + local status, smb_data = smb['socket']:receive_buf(match.numbytes(netbios_length), true) + + -- Make sure the connection is still alive + if not status then + return false, "SMB2: Failed to receive bytes after 5 attempts: " .. smb_data + end + + local result = netbios_data .. smb_data + if(#result ~= length) then + stdnse.debug1("SMB2: ERROR: Received wrong number of bytes, there will likely be issues (received %d, expected %d)", #result, length) + return false, string.format("SMB2: ERROR: Didn't receive the expected number of bytes; received %d, expected %d. This will almost certainly cause some errors.", #result, length) + end + + -- The header is 64 bytes. + if (pos + 64 > #result) then + stdnse.debug2("SMB2: SMB2 packet too small. Size needed to be at least '%d' but we got '%d' bytes", pos+64, #result) + return false, "SMB2: ERROR: Header packet too small." + end + local header, pos = string.unpack("<c64", result, pos) + + -- Read the data section or skip it if read_data is false. + local data + if(read_data == nil or read_data == true) then + data = result:sub(pos) + end + + stdnse.debug3("SMB2: smb2_read() received %d bytes", #result) + return true, header, data +end + +--- +-- Sends SMB2_COM_NEGOTIATE command for a SMB2/SMB3 connection. +-- All supported dialects are offered. Use table overrides['Dialects'] +-- to exclude some dialects or to force a specific dialect. +-- Use function smb2.dialects to obtain the list of supported dialects. +-- Use function smb2.dialect_name to check whether a given dialect is supported. +-- +-- Packet structure: +-- https://docs.microsoft.com/en-us/openspecs/windows_protocols/ms-smb2/e14db7ff-763a-4263-8b10-0c3944f52fc5 +-- +-- @param smb The associated SMB connection object. +-- @param overrides Overrides table. +-- @return (status, dialect) If status is true, the negotiated dialect is returned as the second value. +-- Otherwise if status is false, the error message is returned. +-- @see dialects +-- @see dialect_name +function negotiate_v2(smb, overrides) + overrides = overrides or {} + local StructureSize = 36 -- Must be set to 36. + local Dialects = overrides['Dialects'] or smb2_dialects + local DialectCount = #Dialects + -- The client MUST set SecurityMode bit to 0x01 if the SMB2_NEGOTIATE_SIGNING_REQUIRED bit is not set, + -- and MUST NOT set this bit if the SMB2_NEGOTIATE_SIGNING_REQUIRED bit is set. + -- The server MUST ignore this bit. + local SecurityMode = overrides["SecurityMode"] or smb2_values['SMB2_NEGOTIATE_SIGNING_ENABLED'] + local Capabilities = overrides["Capabilities"] or 0 -- SMB 3.x dialect requires capabilities to be constructed + local GUID = overrides["GUID"] or "1234567890123456" + local ClientStartTime = overrides["ClientStartTime"] or 0 -- ClientStartTime only used in dialects < 3.1.1 + local total_data = 0 -- Data counter + local padding_data = "" -- Padding string to align contexts + local context_data -- Holds Context data + local is_0311 = tableaux.contains(Dialects, 0x0311) -- Flag for SMB 3.1.1 + local status, err + + local header = smb2_encode_header_sync(smb, command_codes['SMB2_COM_NEGOTIATE'], overrides) + + -- We construct the first block that works for dialects 2.0.2 up to 3.1.1. + local data = string.pack("<I2 I2 I2 I2 I4 c16", + StructureSize, -- 2 bytes: StructureSize + DialectCount, -- 2 bytes: DialectCount + SecurityMode, -- 2 bytes: SecurityMode + 0, -- 2 bytes: Reserved - Must be 0 + Capabilities, -- 4 bytes: Capabilities - 0 for dialects > 3.x + GUID -- 16 bytes: ClientGuid + ) + + -- The next block gets interpreted in different ways depending on the dialect + -- If we are dealing with 3.1.1 we need to set the following fields: + -- NegotiateContextOffset, NegotiateContextCount, and Reserved2 + if is_0311 then + total_data = #header + #data + (DialectCount*2) + padding_data = string.rep("\0", (8 - total_data % 8) % 8) + total_data = total_data + #padding_data + data = data .. string.pack("<I4 I2 I2", + total_data+8, -- NegotiateContextOffset (4 bytes) + 0x2, -- NegotiateContextCount (2 bytes) + 0x0 -- Reserved2 (2 bytes) + ) + else -- If it's not 3.1.1, the bytes are the ClientStartTime (8 bytes) + data = data .. string.pack("<I8", ClientStartTime) + end -- if is_0311 + + -- Now we build the Dialect list, 16 bit integers + for _, v in ipairs(Dialects) do + data = data .. string.pack("<I2", v) + end + + -- If 3.11, we now need to add some padding between the dialects and the NegotiateContextList + -- I was only able to get this to work using both NegotiateContexts: + -- * SMB2_PREAUTH_INTEGRITY_CAPABILITIES + -- * SMB2_ENCRYPTION_CAPABILITIES + if is_0311 then + data = data .. padding_data + local negotiate_context_list, context_data + + -- We set SMB2_ENCRYPTION_CAPABILITIES first + context_data = string.pack("<I2 I2 I2", + 0x2, -- CipherCount (2 bytes): 2 ciphers available + 0x0002, -- Ciphers (2 bytes each): AES-128-GCM + 0x0001 -- Ciphers (2 bytes each): AES-128-CCM + ) + data = data .. string.pack("<I2 I2 I4", + smb2_values['SMB2_ENCRYPTION_CAPABILITIES'],-- ContextType (2 bytes) + #context_data, -- DataLength (2 bytes) + 0x0 -- Reserved (4 bytes) + ) .. context_data -- Data (SMB2_ENCRYPTION_CAPABILITIES) + + -- We now add SMB2_PREAUTH_INTEGRITY_CAPABILITIES + -- We add the padding between contexts so they are 8 byte aligned + total_data = #header + #data + padding_data = string.rep("\0", (8 - total_data % 8) % 8) + data = data .. padding_data + context_data = context_data .. string.pack("<I2 I2 I2 I16 I16", + 0x1, -- HashAlgorithmCount (2 bytes) + 0x20, -- SaltLength (2 bytes) + 0x0001, -- HashAlgorithms (2 bytes each): SHA-512 + 0x0, -- Salt + 0x1 -- Salt + ) + data = data .. string.pack("<I2 I2 I4", + smb2_values['SMB2_PREAUTH_INTEGRITY_CAPABILITIES'], -- ContextType (2 bytes) + #context_data, -- DataLength (2 bytes) + 0x0 -- Reserved (4 bytes) + ) .. context_data + + end + + status, err = smb2_send(smb, header, data) + if not status then + return false, err + end + status, header, data = smb2_read(smb) + + local protocol_version, structure_size, credit_charge, status = string.unpack("<c4 I2 I2 I4", header) + -- Get the protocol version + if(protocol_version ~= ("\xFESMB") or structure_size ~= 64) then + return false, "SMB: Server returned an invalid SMBv2 packet" + end + stdnse.debug2("SMB2_COM_NEGOTIATE returned status '%s'", status) + + if status ~= 0 then + stdnse.debug2("SMB2_COM_NEGOTIATE command failed: Dialect not supported.") + return false, "SMB2: Dialect is not supported. Exiting." + end + + local parameters_format = "<I2 I2 I2 I2 c16 I4 I4 I4 I4 I8 I8" + if #data < string.packsize(parameters_format) then + -- smb.lua can tolerate missing time/timezone, but it's less likely any + -- SMB2 implementations will not have them. If this becomes a problem, we + -- can shorten this unpack format like in smb.negotiate_v1 + return false, "SMB2: ERROR: Server returned less data than it was supposed to (one or more fields are missing)" + end + + local data_structure_size, security_mode, negotiate_context_count + data_structure_size, smb['security_mode'], smb['dialect'], + negotiate_context_count, smb['server_guid'], smb['capabilities'], + smb['max_trans'], smb['max_read'], smb['max_write'], smb['time'], + smb['start_time'] = string.unpack(parameters_format, data) + + if(data_structure_size ~= 65) then + return false, string.format("Server returned an unknown structure size in SMB2 NEGOTIATE response") + end + + -- Convert the time and timezone to human readable values (taken from smb.lua) + smb['time'] = (smb['time'] // 10000000) - 11644473600 + smb['date'] = datetime.format_timestamp(smb['time']) + + -- Samba does not report the boot time + if smb['start_time'] ~= 0 then + smb['start_time'] = (smb['start_time'] // 10000000) - 11644473600 + smb['start_date'] = datetime.format_timestamp(smb['start_time']) + else + smb['start_date'] = "N/A" + end + + local security_buffer_offset, security_buffer_length, neg_context_offset + security_buffer_offset, security_buffer_length, neg_context_offset = string.unpack("<I2 I2 I4", data) + if status == 0 then + return true, smb['dialect'] + else + return false, string.format("Status error code:%s",status) + end +end + +return _ENV; |