CrackMe® Practices for Newbies
PROJECT 6: caveman by Ghiribizzo

kinda stuck...
Tuesday, 23-Feb-99 11:58:51

    kinda stuck here...

    :017f xor al,ah
    :0181 and ah,01 -> ax is now 011a for me
    :0186 div bl -> divide accumulator by bl
    for me this is 011a/4e (4e was mov'ed into bl earlier)
    :0188 movsx si,ah ->move with sign extended
    src to dest...si is now 0030 for me
    :018b add si, 010b
    :018f mov [065c], si -> [065c] now 3b01
    :0193 mov bx,0660 -> T.abcfw location
    :0196 mov si,01b1 -> si points to index table...
    :0199 mov di,0100 -> destination index
    :019c lodsb -> x'fers string element addressed by ds:si to accumulator...

    *** here is the xlat loop ****

    jmp's back here from :01af

    :019d cmp al, 00 -> check for zero terminator
    :019f jz 01d0 -> jmp if zero
    :01a1 mov cl,al -> cl now equals 0b
    :01a3 and ax, 00f0 -> * why? *
    :01a6 shr al, 04 -> * why? *
    :01a9 xlat -> replaces byte in al with byte from a user table addressed by Bx...the original value of al is the index into the translate table (BX=0660...this is the T.abcfw string...AL is now '54' or 'T'...
    :01aa and cl, 0f -> * why? * cx remains 000b
    :01ad repz stosb -> repeats execution of string instruction while cx!=0...Cx is decremented after each operation...stosb store string byte in accumulator to location di, di is incremented by sizeof(operand)...

    :01af jmp 019c -> back to top of loop...


    ***** this puts a lot of 'T' 's into memory starting at location :0100 then kicks me out with
    the same old "bad file error"...

    I'm kinda stuck again...any advice on what direction to take now?

    snakebyte__


Message thread:

snakebyte's thread (snakebyte__@hotmail.com) (20-Feb-99 09:08:43)

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