140 lines
2.4 KiB
NASM
140 lines
2.4 KiB
NASM
format binary
|
|
use32
|
|
include 'std.inc'
|
|
|
|
; On entrance to each shellcode segment the ebx register will be a vtable of std funcs
|
|
; printf
|
|
; puts
|
|
; scanf
|
|
; sin
|
|
; cos
|
|
; tan
|
|
; asin
|
|
; acos
|
|
; atan
|
|
; malloc
|
|
; free
|
|
; esi contains the base address of the shellcode segment
|
|
; edi contains the address of the part of the flag that this segment fills
|
|
; edx contains the number of the block
|
|
|
|
start:
|
|
push edx
|
|
push edi
|
|
push esi
|
|
|
|
mov eax, dword [ebx]
|
|
lea ecx, [esi + base_txt]
|
|
push ecx
|
|
call dword [eax]
|
|
add esp, 4
|
|
|
|
xor eax, eax
|
|
push eax
|
|
mov eax, esp
|
|
push eax
|
|
|
|
lea eax, [ebx + 8]
|
|
mov eax, dword [eax]
|
|
lea ecx, [esi+scanf_txt]
|
|
push ecx
|
|
call dword [eax]
|
|
add esp, 8
|
|
|
|
; inputt'd float is now on top of the stack
|
|
pop eax
|
|
mov dword [esi+temp_val], eax
|
|
|
|
sub esp, 8
|
|
cvtss2sd xmm0, dword [esi+temp_val]
|
|
movsd qword [esp], xmm0
|
|
|
|
; call cos
|
|
lea eax, [ebx + 0x10]
|
|
mov eax, dword [eax]
|
|
call dword [eax]
|
|
|
|
fstp qword [esp]
|
|
movsd xmm0, qword [esp]
|
|
add esp, 8
|
|
cvtss2sd xmm1, dword [esi+c_val]
|
|
mulsd xmm0, xmm1
|
|
push ebp
|
|
push ebp
|
|
movsd qword [esp], xmm0
|
|
|
|
; call atan
|
|
lea eax, [ebx + 0x20]
|
|
mov eax, dword [eax]
|
|
call dword [eax]
|
|
|
|
fstp qword [esp]
|
|
movsd xmm0, qword [esp]
|
|
pop eax
|
|
cvtss2sd xmm1, dword [esi+b_val]
|
|
pop ecx
|
|
mulsd xmm0, xmm1
|
|
push esp
|
|
push ebp
|
|
movsd qword [esp], xmm0
|
|
|
|
; call sin
|
|
lea eax, [ebx + 0xc]
|
|
mov eax, dword [eax]
|
|
call dword [eax]
|
|
|
|
fstp qword [esp]
|
|
cvtss2sd xmm1, dword [esi+a_val]
|
|
movsd xmm0, qword [esp]
|
|
mulsd xmm0, xmm1
|
|
|
|
movsd qword [esp], xmm0
|
|
cvtsd2ss xmm0, qword [esp]
|
|
pop eax
|
|
movss dword [esp], xmm0
|
|
pop eax
|
|
|
|
pop esi
|
|
push esi
|
|
|
|
cmp eax, dword [esi+final_val]
|
|
jnz trash
|
|
lea ecx, [esi+right_txt]
|
|
jmp past_trash
|
|
trash:
|
|
lea ecx, [esi+wrong_txt]
|
|
; Make this so it crashes badly
|
|
inc esp
|
|
past_trash:
|
|
push ecx
|
|
lea eax, [ebx + 0x4]
|
|
mov eax, dword [eax]
|
|
call dword [eax]
|
|
pop ebp
|
|
|
|
pop esi
|
|
pop edi
|
|
pop edx
|
|
|
|
mov eax, dword [esi+temp_val]
|
|
; 0x336a687b = little endian of '{hj3'
|
|
; 0x336a687b ^ 0x3fab396d which is the value of the correct input 1.33769
|
|
; is equal to 0x5e9c6316
|
|
xor eax, 0xcc15116
|
|
mov dword [edi], eax
|
|
xor eax, eax
|
|
mov dword [esi+temp_val], eax
|
|
|
|
retn
|
|
|
|
b_val dd 0x4039999a
|
|
base_txt db 'Please enter the best number, round to 6 significant figures.', ENDL, 0
|
|
a_val dd 0x40d00000
|
|
scanf_txt db '%f', 0
|
|
final_val dd 0xc092e6a0
|
|
right_txt db 'You got it!', 0
|
|
c_val dd 0xbf99999a
|
|
wrong_txt db 'You dumb.', 0
|
|
temp_val dd 0
|
|
|
|
resv_stuff 512-$
|