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9.1

Binary Bomb Phase 3

Asked by purewin in Assembly Programming Language, C Programming Language, Algorithms

I'm working on phase three of the bomb and I think I have a general idea on what kind of input I need was wondering if someone could verify.

It looks like I need to pass two inputs and the inputs can vary. The first input would be stored at
0x08048cd7 <phase_3+6>: lea    -0x8(%ebp),%eax
stored at (ebp-8)

then the second input would be stored at
0x08048cde <phase_3+13>:        lea    -0x4(%ebp),%eax
stored at (ebp-4)

then if input 2 at (ebp-4) <= 7
switch(*(ebp-4))
which switches to one of the statements depending on what the value of *(ebp-4) is.
which would then set the value of eax depending on the statement switched to.
which would then jump to the memory location referenced in the switch case which then performs an operation on eax and sets eax equal to the result.
then if *(ebp - 4) > 5 or eax != *(ebp - 8)
bomb_explode is called
otherwise phase is diffused

Am i interpreting this correctly?
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Dump of assembler code for function phase_3:
0x08048cd1 <phase_3+0>: push   %ebp
0x08048cd2 <phase_3+1>: mov    %esp,%ebp
0x08048cd4 <phase_3+3>: sub    $0x28,%esp
0x08048cd7 <phase_3+6>: lea    -0x8(%ebp),%eax
0x08048cda <phase_3+9>: mov    %eax,0xc(%esp)
0x08048cde <phase_3+13>:        lea    -0x4(%ebp),%eax
0x08048ce1 <phase_3+16>:        mov    %eax,0x8(%esp)
0x08048ce5 <phase_3+20>:        movl   $0x80497bb,0x4(%esp)
0x08048ced <phase_3+28>:        mov    0x8(%ebp),%eax
0x08048cf0 <phase_3+31>:        mov    %eax,(%esp)
0x08048cf3 <phase_3+34>:        call   0x8048828 <sscanf@plt>
0x08048cf8 <phase_3+39>:        cmp    $0x1,%eax
0x08048cfb <phase_3+42>:        jg     0x8048d02 <phase_3+49>
0x08048cfd <phase_3+44>:        call   0x8048f2c <explode_bomb>
0x08048d02 <phase_3+49>:        cmpl   $0x7,-0x4(%ebp)
0x08048d06 <phase_3+53>:        ja     0x8048d73 <phase_3+162>
0x08048d08 <phase_3+55>:        mov    -0x4(%ebp),%eax
0x08048d0b <phase_3+58>:        jmp    *0x804974c(,%eax,4)
0x08048d12 <phase_3+65>:        mov    $0x0,%eax
0x08048d17 <phase_3+70>:        jmp    0x8048d6c <phase_3+155>
0x08048d19 <phase_3+72>:        mov    $0x0,%eax
0x08048d1e <phase_3+77>:        xchg   %ax,%ax
0x08048d20 <phase_3+79>:        jmp    0x8048d67 <phase_3+150>
0x08048d22 <phase_3+81>:        mov    $0x0,%eax
0x08048d27 <phase_3+86>:        jmp    0x8048d62 <phase_3+145>
0x08048d29 <phase_3+88>:        mov    $0x0,%eax
0x08048d2e <phase_3+93>:        xchg   %ax,%ax
0x08048d30 <phase_3+95>:        jmp    0x8048d5d <phase_3+140>
0x08048d32 <phase_3+97>:        mov    $0x0,%eax
0x08048d37 <phase_3+102>:       jmp    0x8048d58 <phase_3+135>
0x08048d39 <phase_3+104>:       mov    $0x0,%eax
0x08048d3e <phase_3+109>:       xchg   %ax,%ax
0x08048d40 <phase_3+111>:       jmp    0x8048d53 <phase_3+130>
0x08048d42 <phase_3+113>:       mov    $0x6a,%eax
0x08048d47 <phase_3+118>:       jmp    0x8048d4e <phase_3+125>
0x08048d49 <phase_3+120>:       mov    $0x0,%eax
0x08048d4e <phase_3+125>:       sub    $0x363,%eax
0x08048d53 <phase_3+130>:       add    $0x396,%eax
0x08048d58 <phase_3+135>:       sub    $0x39d,%eax
0x08048d5d <phase_3+140>:       add    $0x1d2,%eax
0x08048d62 <phase_3+145>:       sub    $0x2ed,%eax
0x08048d67 <phase_3+150>:       add    $0x2ed,%eax
0x08048d6c <phase_3+155>:       sub    $0x331,%eax
0x08048d71 <phase_3+160>:       jmp    0x8048d7d <phase_3+172>
0x08048d73 <phase_3+162>:       call   0x8048f2c <explode_bomb>
---Type <return> to continue, or q <return> to quit---
0x08048d78 <phase_3+167>:       mov    $0x0,%eax
0x08048d7d <phase_3+172>:       cmpl   $0x5,-0x4(%ebp)
0x08048d81 <phase_3+176>:       jg     0x8048d88 <phase_3+183>
0x08048d83 <phase_3+178>:       cmp    -0x8(%ebp),%eax
0x08048d86 <phase_3+181>:       je     0x8048d8d <phase_3+188>
0x08048d88 <phase_3+183>:       call   0x8048f2c <explode_bomb>
0x08048d8d <phase_3+188>:       leave  
0x08048d8e <phase_3+189>:       xchg   %ax,%ax
0x08048d90 <phase_3+191>:       ret    
End of assembler dump.
 
Related Solutions
Keywords: Binary Bomb Phase 3
Title
1 Binary Bomb Phase 2
2 binary bomb phase 6
3 Diffusing A Binary Bomb
4 binary bomb phase 3
5 Binary Bomb Final Phase
6 Binary Bomb - Phase_5 - Assembly
 
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[+][-]10/19/09 10:37 PM, ID: 25611256Accepted Solution

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Zones: Assembly Programming Language, C Programming Language, Algorithms
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Solution Provided By: Infinity08
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Solution Grade: A
 
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