Assembly Language for Beginners

(nextflipdebug2) #1

8.5. DONGLES


.text:0000A43C arg_4 = dword ptr 0Ch
.text:0000A43C arg_8 = dword ptr 10h
.text:0000A43C arg_C = dword ptr 14h
.text:0000A43C
.text:0000A43C push ebp
.text:0000A43D mov ebp, esp
.text:0000A43F sub esp, 54h
.text:0000A442 push edi
.text:0000A443 mov ecx, [ebp+arg_8]
.text:0000A446 xor edi, edi
.text:0000A448 test ecx, ecx
.text:0000A44A push esi
.text:0000A44B jle short loc_A466
.text:0000A44D mov esi, [ebp+arg_C] ; key
.text:0000A450 mov edx, [ebp+arg_4] ; string
.text:0000A453
.text:0000A453 loc_A453: ; CODE XREF: err_warn+28j
.text:0000A453 xor eax, eax
.text:0000A455 mov al, [edx+edi]
.text:0000A458 xor eax, esi
.text:0000A45A add esi, 3
.text:0000A45D inc edi
.text:0000A45E cmp edi, ecx
.text:0000A460 mov [ebp+edi+var_55], al
.text:0000A464 jl short loc_A453
.text:0000A466
.text:0000A466 loc_A466: ; CODE XREF: err_warn+Fj
.text:0000A466 mov [ebp+edi+var_54], 0
.text:0000A46B mov eax, [ebp+arg_0]
.text:0000A46E cmp eax, 18h
.text:0000A473 jnz short loc_A49C
.text:0000A475 lea eax, [ebp+var_54]
.text:0000A478 push eax
.text:0000A479 call status_line
.text:0000A47E add esp, 4
.text:0000A481
.text:0000A481 loc_A481: ; CODE XREF: err_warn+72j
.text:0000A481 push 50h
.text:0000A483 push 0
.text:0000A485 lea eax, [ebp+var_54]
.text:0000A488 push eax
.text:0000A489 call memset
.text:0000A48E call pcv_refresh
.text:0000A493 add esp, 0Ch
.text:0000A496 pop esi
.text:0000A497 pop edi
.text:0000A498 mov esp, ebp
.text:0000A49A pop ebp
.text:0000A49B retn
.text:0000A49C
.text:0000A49C loc_A49C: ; CODE XREF: err_warn+37j
.text:0000A49C push 0
.text:0000A49E lea eax, [ebp+var_54]
.text:0000A4A1 mov edx, [ebp+arg_0]
.text:0000A4A4 push edx
.text:0000A4A5 push eax
.text:0000A4A6 call pcv_lputs
.text:0000A4AB add esp, 0Ch
.text:0000A4AE jmp short loc_A481
.text:0000A4AE err_warn endp


That’s why we were unable to find the error messages in the executable files, because they are encrypted
(which is is popular practice).


Another call to theSSQ()hashing function passes the “offln” string to it and compares the result with
0xFE81and0x12A9.


If they don’t match, it works with sometimer()function (maybe waiting for a poorly connected dongle
to be reconnected and check again?) and then decrypts another error message to dump.

Free download pdf