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Current File : //usr/share/nmap/nselib/smb2.lua
---
-- Implements the Server Message Block (SMB) protocol version 2 and 3.
--
-- The implementation extends smb.lua to support SMB dialects 2.02, 2.10, 3.0,
-- 3.02 and 3.11. 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_names = {}
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 smb2_values_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
}
for i, v in pairs(command_codes) do
command_names[v] = i
end
for i, v in pairs(smb2_values) do
smb2_values_codes[v] = i
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.
-- This function works for dialects 2.02, 2.10, 3.0, 3.02 and 3.11.
--
-- Packet structure: https://msdn.microsoft.com/en-us/library/cc246543.aspx
--
-- @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.
function negotiate_v2(smb, overrides)
local StructureSize = 36 -- Must be set to 36.
local DialectCount
if overrides['Dialects'] then
DialectCount = #overrides['Dialects']
else
DialectCount = 1
end
-- 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 > 3.11
local total_data = 0 -- Data counter
local padding_data = "" -- Padding string to align contexts
local context_data -- Holds Context data
local is_0311 = false -- Flag for SMB 3.11
local status, err
if not( overrides['Dialects'] ) then -- Set 2.02 as default dialect if user didn't select one
overrides['Dialects'] = {0x0202}
end
local header = smb2_encode_header_sync(smb, command_codes['SMB2_COM_NEGOTIATE'], overrides)
-- We construct the first block that works for dialects 2.02 up to 3.11.
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 tableaux.contains(overrides['Dialects'], 0x0311) then
is_0311 = true
end
-- If we are dealing with 3.11 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 3.11, the bytes are the ClientStartTime (8 bytes)
data = data .. string.pack("<I8", ClientStartTime) -- If it is not 3.11, we set it to 0
end -- if is_0311
-- Now we build the Dialect list, 16 bit integers
if(overrides['Dialects'] == nil) then -- If no custom dialect is defined, used the default 2.10
data = data .. string.pack("<I2", 0x0210)
else -- Dialects are set in overrides table
for _, v in ipairs(overrides['Dialects']) do
data = data .. string.pack("<I2", v)
end
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, overrides['Dialects']
else
return false, string.format("Status error code:%s",status)
end
end
return _ENV;
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