The main daemon is the. Regardless, the first user inputed value had to be less than or equal to 14 and had to spit out an 11 after its computation. The two stipulations that you must satisfy to move to the last portion of this phase is that you have incremented the counter to 15 and that the final value when you leave the loop is 0xf (decimal 15). Either way, eventually youll find that the pre-cyphered version of giants is actually opekmq. Each phase reads a line from the standard input. There is a small grade penalty for explosions beyond 20. For each bomb, it tallies the number, of explosions, the last defused phase, validates each last defused, phase using a quiet copy of the bomb, and computes a score for each, student in a tab delimited text file called "scores.txt." Let's enter the string blah as our input to phase_1 . string_length If your, Linux box crashes or reboots, simply restart the daemons with "make, * Information and error messages from the servers are appended to the, "status log" in bomblab/log-status.txt. In this part we use objdump to get the assembly code We multiply the number by 2 each step, so we guess the sequence to be 1, 2, 4, 8, 16, 32, which is the answer. In the first block of code, the function read_six_numbers is called which essentially confirms that it is six numbers which are seperated by a space (as we entered in the first part of this phase). Phase 4: recursive calls and the stack discipline. Use Git or checkout with SVN using the web URL. Unexpected uint64 behaviour 0xFFFF'FFFF'FFFF'FFFF - 1 = 0? We have created a stand-alone user-level autograding service that, handles all aspects of the Bomb Lab for you: Students download their, bombs from a server. You have 6 phases with which to blow yourself up. requires that you keep the autograding service running non-stop, because handouts, grading, and reporting occur continuously for the, duration of the lab. Enter disas and you will get a chunk of assembly for the function phase_1 which we put our breakpoint at. Learn more. phase_3() - In this phase you are required to type in another code of at least 2 numbers. Contribute to xmpf/cse351 development by creating an account on GitHub. It's provided only for completeness. After solving stage 1 you likely get the string 'Phase 1 defused. What are the advantages of running a power tool on 240 V vs 120 V? executable file 271 lines (271 sloc) 7.74 KB. If nothing happens, download GitHub Desktop and try again. Some of the pass phrases could be integers, or a random set of characters if that is the case then the only way to figure things out is through dynamic analysis and disassembling the code. The nefarious Dr. * phase2a.c - To defeat this stage the user must enter a sequence of, * 6 nonnegative numbers where x[i] = x[i-1] + i. From this mapping table, we can figure out the un-cyphered version of giants. Once we understand how it works, we can reverse engineer giants into its pre-cypher form without having to waste time doing trial and error. The user input is then, 4 5 1 6 2 3. If that function fails, it calls explode_bomb to the left. The answer is that the first input had to be 1. So you think you can stop the bomb with ctrl-c, do you?' Such bombs, We will also find it helpful to distinguish between custom and, Custom Bomb: A "custom bomb" has a BombID > 0, is associated with a, particular student, and can be either notifying or quiet. I cannot describe the question better . What does the power set mean in the construction of Von Neumann universe? p # Change print mode in Visual/Graph mode. Have a nice day! Next, as we scan through each operation, we see that a register is being incremented at , followed by a jump-less-than statement right afterwards that takes us back up to . There was a bunch of manipulation of stack space but there was nothing in the stack at that location and so it is likely a bunch of leg work. . Each phase expects you to type a particular string. The bomb has blown up. Firstly, let's have a look at the asm code. Now lets take a quick look at the disassebly to see what variables are being used. If the first character in the input string is anything but a zero then the detonation flag is set to low and passed out the function. Up till now, there shouldn't be any difficulties. Pull up the function in Graph mode with VV, press p to cycle between views, and select the minigraph. initialize_bomb_solve Tools: Starting challenge; Phase_1: Phase_2: Phase_3: Phase_4: Phase_5: Phase_6: Bomb Lab Write-up. node1 Contribute to CurryTang/bomb_lab_solution development by creating an account on GitHub. Many Git commands accept both tag and branch names, so creating this branch may cause unexpected behavior. Solve a total of 6 phases to defuse the bomb. explode_bomb Each element in the array has an empty element directly adjacent to it. I should say the first half of the code is plain. Remember this structure from Phase 2? Asking for help, clarification, or responding to other answers. Then you can solve this problem by making a table(Yeah, it may seem silly, but I think it's the most convenient way). So you think you can stop the bomb with ctrl-c, do you? There are a ton of dead ends that you can follow in this code that all land on detonation. Ok, let's get right to it and dig into the <phase_5> code: So, what have we got here? BOOM!!! phase_6 I know there has to be 6 numbers, with the range of 1-6, and there can't be any repeats. The report daemon finds the most recent, defusing string submitted by each student for each phase, and, validates these strings by applying them to a local copy of the, student's bomb. Each message contains a BombID, a phase, and an indication of the, event that occurred. Then you get the answer to be the pair(7, 0). If you're looking for a specific phase: Here is Phase 1. This assignment gives you a binary program containing "bombs" which trigger a ping to our server (and make you lose points) if their inputs are wrong. main Then we take a look at the assembly code above, we see one register eax and an address 0x402400. There is an accessed memory area that serves as a counter. Dump of assembler code for function phase_5: 0x0000000000401002 <+0>: sub $0x18,%rsp ; rsp = rsp - 24, 0x0000000000401006 <+4>: lea 0x8(%rsp),%rcx ; rcx = *(rsp + 8) (function argument), 0x000000000040100b <+9>: lea 0xc(%rsp),%rdx ; rdx = *(rsp + 12) (function argument), 0x0000000000401010 <+14>: mov $0x401ebe,%esi ; esi = "%d %d", 0x0000000000401015 <+19>: mov $0x0,%eax ; eax = 0, 0x000000000040101a <+24>: callq 0x400ab0 <__isoc99_sscanf@plt>, 0x000000000040101f <+29>: cmp $0x1,%eax ; if (eax > 1) goto 0x401029, 0x0000000000401022 <+32>: jg 0x401029 , 0x0000000000401024 <+34>: callq 0x40163d ; if (eax <= 1) explode_bomb(), 0x0000000000401029 <+39>: mov 0xc(%rsp),%eax ; eax = *(rsp + 12) ::function parameter, 0x000000000040102d <+43>: and $0xf,%eax ; eax = eax & 0xf (last 2 bits), 0x0000000000401030 <+46>: mov %eax,0xc(%rsp) ; *(rsp + 12) = eax, 0x0000000000401034 <+50>: cmp $0xf,%eax ; if (eax == 0xf) explode_bomb(), 0x0000000000401037 <+53>: je 0x401065 , 0x0000000000401039 <+55>: mov $0x0,%ecx ; ecx = 0, 0x000000000040103e <+60>: mov $0x0,%edx ; edx = 0, 0x0000000000401043 <+65>: add $0x1,%edx ; edx = edx + 0x1, 0x0000000000401046 <+68>: cltq ; sign extend eax to quadword (rax), 0x0000000000401048 <+70>: mov 0x401ba0(,%rax,4),%eax ; eax = *(rax * 4 + 0x401ba0), 0x000000000040104f <+77>: add %eax,%ecx ; ecx = ecx + eax, 0x0000000000401051 <+79>: cmp $0xf,%eax ; if (eax != 0xf) goto 0x401043 (inc edx), 0x0000000000401054 <+82>: jne 0x401043 , 0x0000000000401056 <+84>: mov %eax,0xc(%rsp) ; *(rsp + 12) = eax, 0x000000000040105a <+88>: cmp $0xc,%edx ; if (edx != 12) explode_bomb(), 0x000000000040105d <+91>: jne 0x401065 , 0x000000000040105f <+93>: cmp 0x8(%rsp),%ecx ; if (ecx == *(rsp + 8)) goto 0x40106a, 0x0000000000401063 <+97>: je 0x40106a , 0x0000000000401065 <+99>: callq 0x40163d ; explode_bomb(), 0x000000000040106a <+104>: add $0x18,%rsp ; rsp = rsp + 24, 0x000000000040106e <+108>: retq ; return, --------------------------------------------------------------------------------. phase_4 Stepping through the code with the GDB debugger I can say plenty about the various functions called in this program: I don't want to run the program/"pull the pin" on the bomb by running it, so this tells me that there are likely 6 stages to the bomb. From this, we can guess that to pass phase_1, we need to enter the correct string. The request server, responds by sending an HTML form back to the browser. Using layout asm, we can see the assembly code as we step through the program. (**Please feel free to fork or star if helpful!). phase_6 Alternative paths? Are you sure you want to create this branch? How about the next one? Ahhhh, recursion, right? The request server builds the, bomb, archives it in a tar file, and then uploads the resulting tar, file back to the browser, where it can be saved on disk and, untarred. - Main daemon (bomblab.pl). The second input had to be a 11, because the the phase_4 code did a simple compare, nothing special. Learn more. I then continue to run the program until I am prompted for a phrase to input. As we have learned from the past phases, fixed values are almost always important. DePaul University - System I - Winter 2017, **Note: I made this repo with the intent to help others solve their own Bomb Labs. I start stepping by single instructions until I get to the point where I am about to hit the function strings_not_equal. Not the answer you're looking for? Welcome to my fiendish little bomb. I will likely take another shot at figureing out exactly how to come up with the solution by following the implemented logic but I eventually brute forced it, which took a whole 30 seconds to figure out. secret_phase !!! First, setup your bomb directory. DrEvil This post walks through the first 3 phases of the lab. phase_5 Are you sure you want to create this branch? Any numbers entered after the first 6 can be anything. gdbCfg phase 5. There is also a "secret phase" that, only appears if students append a certain string to the solution to, Each phase has three variants: "a", "b", and "c". There is a small amount of extra credit for each additional phase . METU Ceng'e selamlar :)This is the first part of the Attack Lab. This continuous through all the user inputed indices and finally places the value zero in the last remaining empty element in the array. phase_1 without any ill effects. As a next step, lets input the test string abcdef and take a look at what the loop does to it.
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