If you're looking for a specific phase: Here is Phase 1. Assembly - what does movbzl. Phase 5. (Add 16 each time) ecx is compared to rsp, which is 15, so we need ecx to equal to 15. Here is Phase 5 Here is Phase 6 Phase 1 is sort of the "Hello World" of the Bomb Lab. Off the top of my head, I see many comparison statements, pushing, popping, read six numbers, so that's our input. So, what do we know about phase 5 so far? 0x08048e35 <+91>: add $0xb8,%eax. February 20, 2011. This lab allows you to specify a file for the bomb to read your discovered solutions from at run time. Phase 5 reads in two numbers, the first of which is used as a starting point within a sequence of numbers. I am confused on what needs to be done. These are the precise rules: There are a total of 34 points (1, 1, 3, 5, 5, 5, 7, 7 points for phases 1-8, respectively). Some pattern-recognition will be required. So the answer: 2 -109. You will get full credit for defusing phases 2 and 3 with less than 30 explosions. This was also paired with many add $0x125 and sub $0x125, but ultimately each canceled out till all was left with sub $0x125. A note to the reader: For explanation on how to set up the lab environment see the "Introduction" section of the post. Posted by Avantika Yellapantula at 6:00 AM. Learning Lab GitHub Sponsors Open source guides Connect with others; The ReadME Project Events Community forum . x86 Flags (Condition Code) & Registers - Shumin Blog on [Computer Arch.] x86 Flags (Condition Code) & Registers - Shumin Blog on [Computer Arch.] Details on Grading for Bomb Lab. Evil has planted a slew of "binary bombs" on our machines. 21. The bomb explodes if the number calculated by this function does not equal 49. This is just to show that in order to understand what's going on in the assembly code, one must iterate through the code using gdb fully. This is the 5th phase of the bomb lab, I have been stuck on it for a couple of days. Each phase expects you to type a particular string on stdin. Thus, one possible input is " opukma ". Test case:222 3. read_line returns 134523520, which is an address containing an inputs string, "222 3" in this case.. Use 134523520 as argument to call function atoi, which return input0 or 0 if no input for secret_phase.. Accessing array members in assembler. phase_5 () extracts 6 characters from the content of memory address 0x4050fc ~ 0x40510b, which is " isrveawhobpnutfg ", and these characters should form the string " giants ". Using layout asm, we can see the assembly code as we step through the program. 8048db6: 53 push %ebx. OK, but what are the commands to do all of the above? For lab: defuse phase 1. A binary bomb is a program that consists of a sequence of phases. ECEN 324 - Lab Assignment 2: Defuse a binary bomb. our input has to be a string of 6 characters the function accepts this 6 character string and loops over each character in it Start gdb and disassemble phase_defused: Dump of assembler code for function phase_defused: 0x4015c4 <+0>: sub rsp,0x78 0x4015c8 <+4>: mov rax,QWORD PTR . Phase 4: This is actually pretty short because I was able to catch the sequence early on. 4 Step 2: Defuse Your Bomb; 5 Getting Started; 6 Later Phases; 7 Hints; 8 Submission; 1 Introduction. Carry and Overflow . Set a breakpoint on phase 3 and start the process again and you should come to the following. According to the analysis above, the input characters (in hex) should be " 0x?f, 0x?0, 0x?5, 0x?b, 0x?d, 0x?1 ". For full credit in lab, diffuse phase 1. Kyle Clegg. Related. So I am doing the classic Binary bomb and have managed to get to phase 6 without to much trouble but I've been bashing my head trying to figure out this lat phase so any help would be appreciated. We'll enlist Python to help. A note to the reader: For explanation on how to set up the lab environment see the "Introduction" section of the post. Look at the source file bomb.c to get an idea about the overall structure of the bomb. If you're looking for a specific phase: Here is Phase 1 Here is Phase 2 Here is Phase 3 Here is Phase 5 Here is Phase 6 Phase 4 In my opinion, this is where things start to get tricky. Here is Phase 6. Subtraction of 0xb8-0x125 gives the integer -109, which works with this phase. Each phase expects you to type a . You will get full credit for defusing phase 1 with less than 20 explosions. Let's enter the string blah as our input to phase_1 . Here is Phase 4. The difficulty comes from recursion and another function whose purpose isn't clear from just its name. 08048db5 <phase_6>: 8048db5: 56 push %esi. Phase 1. Go ahead and start gdb and set a breakpoint for explode_bomb. It's pretty long. We discovered back in Phase 0 that the path to the secret phase in through the phase_defused function that is called after completing every phase. Let's take a look at the assembly code. So if my solutions I have found for different phases are in a file called solutions.txt I would run "run solutions.txt" and it would run my bomb with that argument. [Git] Github Access Token [Bomb Lab] Secret Phase [Bomb Lab] Phase 6 [Bomb Lab] Phase 5; Recent Comments [Computer Arch.] (**Please feel free to fork or star if helpful!) Here is Phase 5. this is binary bomb lab phase 5.I didn't solve phase 5. Jumping to the next "instruction" using gdb. There are 2 free explosions (no points lost) for each phase. Alright so this is the ever so popular bomb lab and I am currently on phase 5 and I'm only stuck on two lines. There is a small amount of extra credit for each additional phase . 0. In this phase, it is not enough to simply understand the assembly. Phase 5: Phase 5 is a bit easier than Phase 4. This lab allows you to specify a file for the bomb to read your discovered solutions from at run time. Since Fib(10) = Fib(9 + 1) = 55, we know that the solution for this phase is 9. There is a small grade penalty for explosions beyond 20. Each additional explosion costs you 0.5 points. Link to Bomb Lab Instructions (pdf) in GitHub Repository If you type the correct string, then the . Download and print the gdb quick reference guide. On a roll! Finding the Secret Phase. Looks like it wants 2 numbers and a character this time. What I know so far: first input cannot be 15, 31, 47, etc. Let's start gdb and place a breakpoint on explode_bomb. PHASE 3. Here is Phase 2. Reading assembly language to defuse the bomb from phase 1 to 6 1. Need help understanding Binary Bomb Phase_5-1. I used a linux machine running x86_64. bomb lab phase 5 github Mar 14, 2021 Gersh Park Basketball 0 Comment Step 2: Defuse Your Bomb. Guide and work-through for System I's Bomb Lab at DePaul University. Point breakdown for each phase: Phase 1 - 4: 10 points each; Phase 5 and 6: 15 points each; Total maximum score possible: 70 points; Each time the "bomb explodes", it notifies the server, resulting in a (-)1/5 point deduction from the final score for the lab. Each of you will work with a special "binary bomb". I used the input string:- 10 12 16 7 14 15 (Sum of 74) And indexed it 1 4 5 9 10 14 This is just to show that in order to understand what's going on in the assembly code, one must iterate through the code using gdb fully. If the student enters the expected string, then that phase is "defused." Otherwise the bomb "explodes" by printing "BOOM!!!". Phase 6 We have a loop with iterators %ebx and %edi. So if my solutions I have found for different phases are in a file called solutions.txt I would run "run solutions.txt" and it would run my bomb with that argument. . The goal for the students is to defuse as many phases as possible. Post Outline Intro GDB Phase 1 Phase 2 Phase 3 Resources Intro This post walks through the first 3 phases of the lab. When we hit phase_1, we can see the following code: Pretty confident its looking for 3 inputs this time. Phase 4. The code is comparing the string (presumably our input) stored in %eax to a fixed string stored at 0x804980b. Let's start there. For homework: defuse phases 2 and 3. A binary bomb is a program that consists of a sequence of phases. We're back to having only one correct answer, but to get that we're going to have to write some code. So, our input should be six integers. The following two comparisons indicate 0<input0<=0x3e9.. Use 0x804a720 and input0 as arg1 and arg2 to call function fun7, which must return 5, otherwise bomb explodes. You will have to run through the reverse engineering process, but there won't be much in the way of complicated assembly to decipher or tricky mental hoops to jump through. If you're looking for a specific phase: Here is Phase 1. Let's take a look at the assembly here. I see jumping if not equal. 30. Bomb_Lab. Nonetheless, you will always gain points for completing a phase regardless of how many times the bomb has exploded. Introduction: The nefarious Dr. It needs to be six integers separated by spaces, and each integer needs to be less than or equal to six. This post walks through CMU's 'bomb' lab, which involves defusing a 'bomb' by finding the correct inputs to successive phases in a binary executable using GDB. Dump of assembler code for function phase_5: => 0x0000000000401073 <+0>: push %rbx: 0x0000000000401074 <+1 . 0. Carry and Overflow . A binary bomb is a program that consists of a sequence of phases. Here is Phase 2. Bomb Lab phase 5: 6 char string substitution lookup table, strings_not_equal. Let's look at the first chunk of the disassembled phase_5 function: Notice the call to the string_length function, and the resulting jump away from explode_bomb if the return value is 6. This is an educational video on understanding and solving the Binary Bomb Lab. Changing the second input does not affect the ecx. Phase 4 is our first real jump in difficulty. [Git] Github Access Token [Bomb Lab] Secret Phase [Bomb Lab] Phase 6 [Bomb Lab] Phase 5; Recent Comments [Computer Arch.] Now we have two criteria for our password. A "binary bomb" is a Linux executable C program that consists of six "phases." Each phase expects the student to enter a particular string on stdin. A Mad Programmer got really mad and planted a slew of binary bombs on our class machines. 3 lea's, a cmp of the output to 2 and a jump if greater than. Like the last phase, it has multiple correct answers. 8048db7: 83 ec 44 sub $0x44,%esp. Bomb-Assembly. Here is Phase 6. Binary Bomb Lab :: Phase 3. The purpose of this project is to become more familiar with machine level programming. Learning Lab GitHub Sponsors Open source guides Connect with others; The ReadME Project Events Community forum . This looks familiar! Phase 3: Note: This is a very long section mostly because I kept a long bit of dissasembly code and register data. callq 0x40163d <explode_bomb> ; explode_bomb() 0x000000000040106a <+104>: add $0x18,%rsp ; rsp = rsp + 24 . The final constraint on our input occurs in the nested loops between <phase_6+57> and <phase_6+104>. . Here is Phase 5. Now we know that our input string must contain exactly 6 characters. Binary Phase 5 and Four bit indexes. It reads a the answer line from the user for each phase, then calls a function phase_x that has the code for phase x (x between 1 and 6 for the six phases). A homework will follow in which you should . I know this takes in a string of length 6.I also know that the input has to be added up to be 74[0x4a]. So far from my understanding, two conditions need to be met: edx must equal 0xf, meaning the first input has to be 5, 21, 37, etc. Computer Science questions and answers. To begin, let's take a look at the <phase_1> function in our objdump file: Here is Phase 4. Binary Bomb Lab :: Phase 3. Once that's done, disassemble phase_5. Dump of assembler code for function phase_5: 0x0000000000401002 <+0>: sub $0x18,%rsp ; rsp = rsp - 24 . This is an educational video on understanding and solving the Binary Bomb Lab. Once that's done, disassemble phase_4. We can then set up a breakpoint upon entering phase_1 using b phase_1 and for the function explode_bomb to avoid losing points. I was lucky.

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