Difference between revisions of "CSC231 Lab 2 2015"

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(Created page with "--~~~~ ---- <br /> =Reverse Engineering= <br /> Recreate the original assembly program whose hexdump is shown below. You should call your program '''lab2.asm'''. <br /> <sou...")
 
 
(2 intermediate revisions by the same user not shown)
Line 6: Line 6:
 
<br />
 
<br />
 
Recreate the original assembly program whose hexdump is shown below.  You should call your program '''lab2.asm'''.
 
Recreate the original assembly program whose hexdump is shown below.  You should call your program '''lab2.asm'''.
 +
In the process, answer the following questions:
 +
* what is the name of the original assembly program?
 +
* how many string variables does it contain? 
 +
* what are the names of the strings?
 +
* what are the names of the constants?
 +
* what is the original program's output?
 +
 
<br />
 
<br />
 
<source lang="text">
 
<source lang="text">
 
00000000  7f 45 4c 46 01 01 01 00  00 00 00 00 00 00 00 00  |.ELF............|
 
00000000  7f 45 4c 46 01 01 01 00  00 00 00 00 00 00 00 00  |.ELF............|
 
00000010  02 00 03 00 01 00 00 00  80 80 04 08 34 00 00 00  |............4...|
 
00000010  02 00 03 00 01 00 00 00  80 80 04 08 34 00 00 00  |............4...|
−
00000020  e0 00 00 00 00 00 00 00  34 00 20 00 02 00 28 00  |........4. ...(.|
+
00000020  18 01 00 00 00 00 00 00  34 00 20 00 02 00 28 00  |........4. ...(.|
 
00000030  06 00 03 00 01 00 00 00  00 00 00 00 00 80 04 08  |................|
 
00000030  06 00 03 00 01 00 00 00  00 00 00 00 00 80 04 08  |................|
−
00000040  00 80 04 08 a2 00 00 00  a2 00 00 00 05 00 00 00  |................|
+
00000040  00 80 04 08 b8 00 00 00  b8 00 00 00 05 00 00 00  |................|
−
00000050  00 10 00 00 01 00 00 00  a4 00 00 00 a4 90 04 08  |................|
+
00000050  00 10 00 00 01 00 00 00  b8 00 00 00 b8 90 04 08  |................|
−
00000060  a4 90 04 08 14 00 00 00  14 00 00 00 06 00 00 00  |................|
+
00000060  b8 90 04 08 36 00 00 00  36 00 00 00 06 00 00 00  |....6...6.......|
 
00000070  00 10 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
 
00000070  00 10 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
−
00000080  b8 04 00 00 00 bb 01 00  00 00 ba 14 00 00 00 b9  |................|
+
00000080  b8 04 00 00 00 bb 01 00  00 00 ba 0c 00 00 00 b9  |................|
−
00000090  a4 90 04 08 cd 80 b8 01 00 00 00 bb 00 00 00 00  |................|
+
00000090  ce 90 04 08 cd 80 b8 04 00 00 00 bb 01 00 00 00  |................|
−
000000a0  cd 80 00 00 0a 43 53 43  32 33 31 2c 20 46 61 6c |.....CSC231, Fal|
+
000000a0  ba 16 00 00 00 b9 b8 90  04 08 cd 80 b8 01 00 00  |................|
−
000000b0  6c 20 32 30 31 34 0a 0a  00 2e 73 79 6d 74 61 62 |l 2014....symtab|
+
000000b0  00 bb 00 00 00 00 cd 80  69 74 20 73 69 6d 70 6c |........it simpl|
−
000000c0  00 2e 73 74 72 74 61 62 00 2e 73 68 73 74 72 74 |..strtab..shstrt|
+
000000c0  65 2c 20 53 6d 69 74 68 69 65 73 21 0a 0a 4b 49 |e, Smithies!..KI|
−
000000d0  61 62 00 2e 74 65 78 74 00 2e 64 61 74 61 00 00 |ab..text..data..|
+
000000d0  53 53 3a 20 4b 65 65 70 20 20 59 6f 75 20 67 6f |SS: Keep  You go|
−
000000e0  00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  |................|
+
000000e0  74 20 69 74 21 0a 4e 6f  20 77 61 79 21 0a 00 2e |t it!.No way!...|
−
000000f0  00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
+
000000f0  73 79 6d 74 61 62 00 2e 73 74 72 74 61 62 00 2e |symtab..strtab..|
−
00000100 00 00 00 00 00 00 00 00 1b 00 00 00 01 00 00 00  |................|
+
00000100  73 68 73 74 72 74 61 62  00 2e 74 65 78 74 00 2e  |shstrtab..text..|
−
00000110 06 00 00 00 80 80 04 08 80 00 00 00 22 00 00 00  |............"...|
+
00000110 64 61 74 61 00 00 00 00 00 00 00 00 00 00 00 00  |data............|
−
00000120 00 00 00 00 00 00 00 00  10 00 00 00 00 00 00 00  |................|
+
00000120 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  |................|
−
00000130 21 00 00 00 01 00 00 00  03 00 00 00 a4 90 04 08  |!...............|
+
00000130 00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
−
00000140 a4 00 00 00 14 00 00 00  00 00 00 00 00 00 00 00  |................|
+
00000140 1b 00 00 00 01 00 00 00  06 00 00 00 80 80 04 08  |................|
−
00000150 04 00 00 00 00 00 00 00  11 00 00 00 03 00 00 00  |................|
+
00000150 80 00 00 00 38 00 00 00  00 00 00 00 00 00 00 00  |....8...........|
−
00000160 00 00 00 00 00 00 00 00  b8 00 00 00 27 00 00 00  |............'...|
+
00000160 10 00 00 00 00 00 00 00  21 00 00 00 01 00 00 00  |........!.......|
−
00000170 00 00 00 00 00 00 00 00  01 00 00 00 00 00 00 00  |................|
+
00000170 03 00 00 00 b8 90 04 08  b8 00 00 00 36 00 00 00  |............6...|
−
00000180 01 00 00 00 02 00 00 00  00 00 00 00 00 00 00 00  |................|
+
00000180 00 00 00 00 00 00 00 00  04 00 00 00 00 00 00 00  |................|
−
00000190 d0 01 00 00 b0 00 00 00  05 00 00 00 07 00 00 00  |................|
+
00000190 11 00 00 00 03 00 00 00  00 00 00 00 00 00 00 00  |................|
−
000001a0 04 00 00 00 10 00 00 00  09 00 00 00 03 00 00 00  |................|
+
000001a0 ee 00 00 00 27 00 00 00  00 00 00 00 00 00 00 00  |....'...........|
−
000001b0 00 00 00 00 00 00 00 00  80 02 00 00 35 00 00 00  |............5...|
+
000001b0 01 00 00 00 00 00 00 00  01 00 00 00 02 00 00 00  |................|
−
000001c0 00 00 00 00 00 00 00 00  01 00 00 00 00 00 00 00  |................|
+
000001c0 00 00 00 00 00 00 00 00  08 02 00 00 30 01 00 00  |............0...|
−
000001d0 00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
+
000001d0 05 00 00 00 0f 00 00 00 04 00 00 00 10 00 00 00  |................|
−
000001e0 00 00 00 00 80 80 04 08 00 00 00 00 03 00 01 00  |................|
+
000001e0 09 00 00 00 03 00 00 00  00 00 00 00 00 00 00 00  |................|
−
000001f0 00 00 00 00 a4 90 04 08 00 00 00 00 03 00 02 00  |................|
+
000001f0 38 03 00 00 6c 00 00 00  00 00 00 00 00 00 00 00  |8...l...........|
−
00000200 01 00 00 00 00 00 00 00  00 00 00 00 04 00 f1 ff |................|
+
00000200 01 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
−
00000210 0a 00 00 00 a4 90 04 08  00 00 00 00 00 00 02 00  |................|
+
00000210 00 00 00 00 00 00 00 00  00 00 00 00 80 80 04 08 |................|
−
00000220 0f 00 00 00 14 00 00 00  00 00 00 00 00 00 f1 ff |................|
+
00000220 00 00 00 00 03 00 01 00 00 00 00 00 b8 90 04 08 |................|
−
00000230 00 00 00 00 00 00 00 00 00 00 00 00 04 00 f1 ff |................|
+
00000230 00 00 00 00 03 00 02 00  01 00 00 00 00 00 00 00  |................|
−
00000240 16 00 00 00 80 80 04 08 00 00 00 00 10 00 01 00  |................|
+
00000240 00 00 00 00 04 00 f1 ff  15 00 00 00 01 00 00 00  |................|
−
00000250 1d 00 00 00 b8 90 04 08 00 00 00 00 10 00 02 00  |................|
+
00000250 00 00 00 00 00 00 f1 ff 1a 00 00 00 04 00 00 00  |................|
−
00000260 29 00 00 00 b8 90 04 08  00 00 00 00 10 00 02 00  |)...............|
+
00000260 00 00 00 00 00 00 f1 ff 20 00 00 00 01 00 00 00  |........ .......|
−
00000270 30 00 00 00 b8 90 04 08 00 00 00 00 10 00 02 00  |0...............|
+
00000270 00 00 00 00 00 00 f1 ff  27 00 00 00 b8 90 04 08 |........'.......|
−
00000280 00 6c 61 62 32 2e 61 73  6d 00 6d 65 73 67 00 4d  |.lab2.asm.mesg.M|
+
00000280 00 00 00 00 00 00 02 00 2c 00 00 00 16 00 00 00  |........,.......|
−
00000290 53 47 4c 45 4e 00 5f 73 74 61 72 74 00 5f 5f 62  |SGLEN._start.__b|
+
00000290 00 00 00 00 00 00 f1 ff  32 00 00 00 ce 90 04 08  |........2.......|
−
000002a0  73 73 5f 73 74 61 72 74  00 5f 65 64 61 74 61 00 |ss_start._edata.|
+
000002a0 00 00 00 00 00 00 02 00 37 00 00 00 0c 00 00 00 |........7.......|
−
000002b0 5f 65 6e 64 00                                   |_end.|
+
000002b0  00 00 00 00 00 00 f1 ff  3d 00 00 00 da 90 04 08  |........=.......|
−
000002b5
+
000002c0  00 00 00 00 00 00 02 00  42 00 00 00 0c 00 00 00  |........B.......|
 +
000002d0  00 00 00 00 00 00 f1 ff  48 00 00 00 e6 90 04 08  |........H.......|
 +
000002e0  00 00 00 00 00 00 02 00  00 00 00 00 00 00 00 00  |................|
 +
000002f0  00 00 00 00 04 00 f1 ff  4d 00 00 00 80 80 04 08  |........M.......|
 +
00000300  00 00 00 00 10 00 01 00  54 00 00 00 ee 90 04 08  |........T.......|
 +
00000310  00 00 00 00 10 00 02 00  60 00 00 00 ee 90 04 08  |........`.......|
 +
00000320  00 00 00 00 10 00 02 00  67 00 00 00 f0 90 04 08  |........g.......|
 +
00000330  00 00 00 00 10 00 02 00  00 72 65 76 65 72 73 65  |.........reverse|
 +
00000340  45 6e 67 69 6e 65 65 72  2e 61 73 6d 00 45 58 49  |Engineer.asm.EXI|
 +
00000350  54 00 57 52 49 54 45 00  53 54 44 4f 55 54 00 6d  |T.WRITE.STDOUT.m|
 +
00000360  73 67 31 00 4d 53 47 31  4c 00 6d 73 67 32 00 4d  |sg1.MSG1L.msg2.M|
 +
00000370  53 47 32 4c 00 6d 73 67  33 00 4d 53 47 33 4c 00  |SG2L.msg3.MSG3L.|
 +
00000380  6d 73 67 34 00 5f 73 74  61 72 74 00 5f 5f 62 73  |msg4._start.__bs|
 +
00000390  73 5f 73 74 61 72 74 00  5f 65 64 61 74 61 00 5f  |s_start._edata._|
 +
000003a0 65 6e 64 00                                       |end.|
 +
000003a4
 
</source>
 
</source>
 
<br />
 
<br />
Line 58: Line 80:
 
<br />
 
<br />
 
<br />
 
<br />
 +
 +
=Original Program=
 +
<br />
 +
==Output==
 +
<br />
 +
 +
[aurora]
 +
[08:15:13] ~/public_html/classes/231$: !nasm
 +
nasm -f elf -l reverseEngineer.lst reverseEngineer.asm
 +
 +
[aurora]
 +
[08:15:59] ~/public_html/classes/231$: !ld
 +
ld -melf_i386  -o reverseEngineer reverseEngineer.o
 +
 +
[aurora]
 +
[08:16:01] ~/public_html/classes/231$: ./reverseEngineer
 +
KISS: Keep  it simple, Smithies!
 +
 +
<br />
 +
==Assembly==
 +
<br />
 +
<source lang="asm">
 +
;;; reverseEngineering.asm
 +
;;; D. Thiebaut
 +
;;;
 +
;;; a description of the program
 +
;;;
 +
;;; to assemble and run:
 +
;;;
 +
;;;    nasm -f elf -F  stabs reverseEngineering.asm
 +
;;;    ld -o reverseEngineering reverseEngineering.o
 +
;;;    ./reverseEngineering
 +
;;;
 +
;;; -------------------------------------------------------------------
 +
 +
 +
 +
EXIT    equ            1
 +
WRITE  equ            4
 +
STDOUT  equ            1
 +
       
 +
      ;; ------------------------------------------------------------
 +
;; data areas
 +
;; ------------------------------------------------------------
 +
 +
section .data
 +
msg1    db      "it simple, Smithies!", 10, 10
 +
MSG1L  equ    $-msg1
 +
msg2    db      "KISS: Keep  "
 +
MSG2L  equ    $-msg2
 +
msg3    db      "You got it!", 10
 +
MSG3L  equ    $-msg3
 +
msg4    db      "No way!", 10
 +
       
 +
;; ------------------------------------------------------------
 +
;; code area
 +
;; ------------------------------------------------------------
 +
 +
section .text
 +
global _start
 +
 +
_start:
 +
        mov    eax, 4
 +
        mov    ebx, 1
 +
        mov    edx, MSG2L
 +
        mov    ecx, msg2
 +
        int    0x80
 +
 +
        mov    eax, 4
 +
        mov    ebx, 1
 +
        mov    edx, MSG1L
 +
        mov    ecx, msg1
 +
        int    0x80
 +
 +
;; exit()
 +
 +
mov eax,EXIT
 +
mov ebx,0
 +
int 0x80 ; final system call
 +
</source>
 +
<br />
 +
==Listing==
 +
<br />
 +
<source lang="text">
 +
 +
    1                                  ;;; reverseEngineering.asm
 +
    2                                  ;;; D. Thiebaut
 +
    3                                  ;;;
 +
    4                                  ;;; a description of the program
 +
    5                                  ;;;
 +
    6                                  ;;; to assemble and run:
 +
    7                                  ;;;
 +
    8                                  ;;;    nasm -f elf -F  stabs reverseEngineering.asm
 +
    9                                  ;;;    ld -o reverseEngineering reverseEngineering.o
 +
    10                                  ;;;    ./reverseEngineering
 +
    11                                  ;;;
 +
    12                                  ;;; -------------------------------------------------------------------
 +
    13                                 
 +
    14                                 
 +
    15                                 
 +
    16                                  EXIT    equ            1
 +
    17                                  WRITE  equ            4
 +
    18                                  STDOUT  equ            1
 +
    19                                         
 +
    20                                        ;; ------------------------------------------------------------
 +
    21                                  ;; data areas
 +
    22                                  ;; ------------------------------------------------------------
 +
    23                                 
 +
    24                                  section .data
 +
    25 00000000 69742073696D706C65-    msg1    db      "it simple, Smithies!", 10, 10
 +
    26 00000009 2C20536D6974686965-
 +
    27 00000012 73210A0A         
 +
    28                                  MSG1L  equ    $-msg1
 +
    29 00000016 4B4953533A204B6565-    msg2    db      "KISS: Keep  "
 +
    30 0000001F 702020           
 +
    31                                  MSG2L  equ    $-msg2
 +
    32 00000022 596F7520676F742069-    msg3    db      "You got it!", 10
 +
    33 0000002B 74210A           
 +
    34                                  MSG3L  equ    $-msg3
 +
    35 0000002E 4E6F20776179210A        msg4    db      "No way!", 10
 +
    36                                         
 +
    37                                  ;; ------------------------------------------------------------
 +
    38                                  ;; code area
 +
    39                                  ;; ------------------------------------------------------------
 +
    40                                 
 +
    41                                  section .text
 +
    42                                  global _start
 +
    43                                 
 +
    44                                  _start:
 +
    45 00000000 B804000000                      mov    eax, 4
 +
    46 00000005 BB01000000                      mov    ebx, 1
 +
    47 0000000A BA0C000000                      mov    edx, MSG2L
 +
    48 0000000F B9[16000000]                    mov    ecx, msg2
 +
    49 00000014 CD80                            int    0x80
 +
    50                                 
 +
    51 00000016 B804000000                      mov    eax, 4
 +
    52 0000001B BB01000000                      mov    ebx, 1
 +
    53 00000020 BA16000000                      mov    edx, MSG1L
 +
    54 00000025 B9[00000000]                    mov    ecx, msg1
 +
    55 0000002A CD80                            int    0x80
 +
    56                                 
 +
    57                                  ;; exit()
 +
    58                                 
 +
    59 0000002C B801000000              mov eax,EXIT
 +
    60 00000031 BB00000000              mov ebx,0
 +
    61 00000036 CD80                    int 0x80 ; final system call
 +
 +
 +
</source>
 +
 
<br />
 
<br />
 
<br />
 
<br />

Latest revision as of 13:18, 23 September 2015

--D. Thiebaut (talk) 07:15, 21 September 2015 (EDT)


Reverse Engineering


Recreate the original assembly program whose hexdump is shown below. You should call your program lab2.asm. In the process, answer the following questions:

  • what is the name of the original assembly program?
  • how many string variables does it contain?
  • what are the names of the strings?
  • what are the names of the constants?
  • what is the original program's output?


00000000  7f 45 4c 46 01 01 01 00  00 00 00 00 00 00 00 00  |.ELF............|
00000010  02 00 03 00 01 00 00 00  80 80 04 08 34 00 00 00  |............4...|
00000020  18 01 00 00 00 00 00 00  34 00 20 00 02 00 28 00  |........4. ...(.|
00000030  06 00 03 00 01 00 00 00  00 00 00 00 00 80 04 08  |................|
00000040  00 80 04 08 b8 00 00 00  b8 00 00 00 05 00 00 00  |................|
00000050  00 10 00 00 01 00 00 00  b8 00 00 00 b8 90 04 08  |................|
00000060  b8 90 04 08 36 00 00 00  36 00 00 00 06 00 00 00  |....6...6.......|
00000070  00 10 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
00000080  b8 04 00 00 00 bb 01 00  00 00 ba 0c 00 00 00 b9  |................|
00000090  ce 90 04 08 cd 80 b8 04  00 00 00 bb 01 00 00 00  |................|
000000a0  ba 16 00 00 00 b9 b8 90  04 08 cd 80 b8 01 00 00  |................|
000000b0  00 bb 00 00 00 00 cd 80  69 74 20 73 69 6d 70 6c  |........it simpl|
000000c0  65 2c 20 53 6d 69 74 68  69 65 73 21 0a 0a 4b 49  |e, Smithies!..KI|
000000d0  53 53 3a 20 4b 65 65 70  20 20 59 6f 75 20 67 6f  |SS: Keep  You go|
000000e0  74 20 69 74 21 0a 4e 6f  20 77 61 79 21 0a 00 2e  |t it!.No way!...|
000000f0  73 79 6d 74 61 62 00 2e  73 74 72 74 61 62 00 2e  |symtab..strtab..|
00000100  73 68 73 74 72 74 61 62  00 2e 74 65 78 74 00 2e  |shstrtab..text..|
00000110  64 61 74 61 00 00 00 00  00 00 00 00 00 00 00 00  |data............|
00000120  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
00000130  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
00000140  1b 00 00 00 01 00 00 00  06 00 00 00 80 80 04 08  |................|
00000150  80 00 00 00 38 00 00 00  00 00 00 00 00 00 00 00  |....8...........|
00000160  10 00 00 00 00 00 00 00  21 00 00 00 01 00 00 00  |........!.......|
00000170  03 00 00 00 b8 90 04 08  b8 00 00 00 36 00 00 00  |............6...|
00000180  00 00 00 00 00 00 00 00  04 00 00 00 00 00 00 00  |................|
00000190  11 00 00 00 03 00 00 00  00 00 00 00 00 00 00 00  |................|
000001a0  ee 00 00 00 27 00 00 00  00 00 00 00 00 00 00 00  |....'...........|
000001b0  01 00 00 00 00 00 00 00  01 00 00 00 02 00 00 00  |................|
000001c0  00 00 00 00 00 00 00 00  08 02 00 00 30 01 00 00  |............0...|
000001d0  05 00 00 00 0f 00 00 00  04 00 00 00 10 00 00 00  |................|
000001e0  09 00 00 00 03 00 00 00  00 00 00 00 00 00 00 00  |................|
000001f0  38 03 00 00 6c 00 00 00  00 00 00 00 00 00 00 00  |8...l...........|
00000200  01 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
00000210  00 00 00 00 00 00 00 00  00 00 00 00 80 80 04 08  |................|
00000220  00 00 00 00 03 00 01 00  00 00 00 00 b8 90 04 08  |................|
00000230  00 00 00 00 03 00 02 00  01 00 00 00 00 00 00 00  |................|
00000240  00 00 00 00 04 00 f1 ff  15 00 00 00 01 00 00 00  |................|
00000250  00 00 00 00 00 00 f1 ff  1a 00 00 00 04 00 00 00  |................|
00000260  00 00 00 00 00 00 f1 ff  20 00 00 00 01 00 00 00  |........ .......|
00000270  00 00 00 00 00 00 f1 ff  27 00 00 00 b8 90 04 08  |........'.......|
00000280  00 00 00 00 00 00 02 00  2c 00 00 00 16 00 00 00  |........,.......|
00000290  00 00 00 00 00 00 f1 ff  32 00 00 00 ce 90 04 08  |........2.......|
000002a0  00 00 00 00 00 00 02 00  37 00 00 00 0c 00 00 00  |........7.......|
000002b0  00 00 00 00 00 00 f1 ff  3d 00 00 00 da 90 04 08  |........=.......|
000002c0  00 00 00 00 00 00 02 00  42 00 00 00 0c 00 00 00  |........B.......|
000002d0  00 00 00 00 00 00 f1 ff  48 00 00 00 e6 90 04 08  |........H.......|
000002e0  00 00 00 00 00 00 02 00  00 00 00 00 00 00 00 00  |................|
000002f0  00 00 00 00 04 00 f1 ff  4d 00 00 00 80 80 04 08  |........M.......|
00000300  00 00 00 00 10 00 01 00  54 00 00 00 ee 90 04 08  |........T.......|
00000310  00 00 00 00 10 00 02 00  60 00 00 00 ee 90 04 08  |........`.......|
00000320  00 00 00 00 10 00 02 00  67 00 00 00 f0 90 04 08  |........g.......|
00000330  00 00 00 00 10 00 02 00  00 72 65 76 65 72 73 65  |.........reverse|
00000340  45 6e 67 69 6e 65 65 72  2e 61 73 6d 00 45 58 49  |Engineer.asm.EXI|
00000350  54 00 57 52 49 54 45 00  53 54 44 4f 55 54 00 6d  |T.WRITE.STDOUT.m|
00000360  73 67 31 00 4d 53 47 31  4c 00 6d 73 67 32 00 4d  |sg1.MSG1L.msg2.M|
00000370  53 47 32 4c 00 6d 73 67  33 00 4d 53 47 33 4c 00  |SG2L.msg3.MSG3L.|
00000380  6d 73 67 34 00 5f 73 74  61 72 74 00 5f 5f 62 73  |msg4._start.__bs|
00000390  73 5f 73 74 61 72 74 00  5f 65 64 61 74 61 00 5f  |s_start._edata._|
000003a0  65 6e 64 00                                       |end.|
000003a4




Original Program


Output


[aurora]
[08:15:13] ~/public_html/classes/231$: !nasm
nasm -f elf -l reverseEngineer.lst reverseEngineer.asm

[aurora]
[08:15:59] ~/public_html/classes/231$: !ld
ld -melf_i386  -o reverseEngineer reverseEngineer.o

[aurora]
[08:16:01] ~/public_html/classes/231$: ./reverseEngineer 
KISS: Keep  it simple, Smithies!


Assembly


;;; reverseEngineering.asm
;;; D. Thiebaut
;;; 
;;; a description of the program
;;;
;;; to assemble and run:
;;;
;;;     nasm -f elf -F  stabs reverseEngineering.asm
;;;     ld -o reverseEngineering reverseEngineering.o
;;;     ./reverseEngineering
;;; 
;;; -------------------------------------------------------------------



EXIT    equ             1
WRITE   equ             4
STDOUT  equ             1
        
      	;; ------------------------------------------------------------
	;; data areas
	;; ------------------------------------------------------------

	section	.data
msg1    db      "it simple, Smithies!", 10, 10
MSG1L   equ     $-msg1
msg2    db      "KISS: Keep  "
MSG2L   equ     $-msg2
msg3    db      "You got it!", 10
MSG3L   equ     $-msg3
msg4    db      "No way!", 10
        
	;; ------------------------------------------------------------
	;; code area
	;; ------------------------------------------------------------

	section	.text
	global	_start

_start:
        mov     eax, 4
        mov     ebx, 1
        mov     edx, MSG2L
        mov     ecx, msg2
        int     0x80

        mov     eax, 4
        mov     ebx, 1
        mov     edx, MSG1L
        mov     ecx, msg1
        int     0x80

	;; exit()

	mov	eax,EXIT
	mov	ebx,0
	int	0x80		; final system call


Listing


     1                                  ;;; reverseEngineering.asm
     2                                  ;;; D. Thiebaut
     3                                  ;;; 
     4                                  ;;; a description of the program
     5                                  ;;;
     6                                  ;;; to assemble and run:
     7                                  ;;;
     8                                  ;;;     nasm -f elf -F  stabs reverseEngineering.asm
     9                                  ;;;     ld -o reverseEngineering reverseEngineering.o
    10                                  ;;;     ./reverseEngineering
    11                                  ;;; 
    12                                  ;;; -------------------------------------------------------------------
    13                                  
    14                                  
    15                                  
    16                                  EXIT    equ             1
    17                                  WRITE   equ             4
    18                                  STDOUT  equ             1
    19                                          
    20                                        	;; ------------------------------------------------------------
    21                                  	;; data areas
    22                                  	;; ------------------------------------------------------------
    23                                  
    24                                  	section	.data
    25 00000000 69742073696D706C65-     msg1    db      "it simple, Smithies!", 10, 10
    26 00000009 2C20536D6974686965-
    27 00000012 73210A0A           
    28                                  MSG1L   equ     $-msg1
    29 00000016 4B4953533A204B6565-     msg2    db      "KISS: Keep  "
    30 0000001F 702020             
    31                                  MSG2L   equ     $-msg2
    32 00000022 596F7520676F742069-     msg3    db      "You got it!", 10
    33 0000002B 74210A             
    34                                  MSG3L   equ     $-msg3
    35 0000002E 4E6F20776179210A        msg4    db      "No way!", 10
    36                                          
    37                                  	;; ------------------------------------------------------------
    38                                  	;; code area
    39                                  	;; ------------------------------------------------------------
    40                                  
    41                                  	section	.text
    42                                  	global	_start
    43                                  
    44                                  _start:
    45 00000000 B804000000                      mov     eax, 4
    46 00000005 BB01000000                      mov     ebx, 1
    47 0000000A BA0C000000                      mov     edx, MSG2L
    48 0000000F B9[16000000]                    mov     ecx, msg2
    49 00000014 CD80                            int     0x80
    50                                  
    51 00000016 B804000000                      mov     eax, 4
    52 0000001B BB01000000                      mov     ebx, 1
    53 00000020 BA16000000                      mov     edx, MSG1L
    54 00000025 B9[00000000]                    mov     ecx, msg1
    55 0000002A CD80                            int     0x80
    56                                  
    57                                  	;; exit()
    58                                  
    59 0000002C B801000000              	mov	eax,EXIT
    60 00000031 BB00000000              	mov	ebx,0
    61 00000036 CD80                    	int	0x80		; final system call

















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