invalid_phase Cannot retrieve contributors at this time. I found various strings of interest. fun7 ??? After looking at the static Main() code, I've got a reasonable understanding of the gross control flow through this program now lets do a more dynamic analysis with GDB. At each iteration, we check to see that the current value is double the previous value. executable file 271 lines (271 sloc) 7.74 KB. We get the following part, We see a critical keyword Border, right? Each phase expects you to type a particular string. A tag already exists with the provided branch name. OK. :-) In this part, we are given two functions phase_4() and func4(). So, I mapped out the array from element 0 to 15 and then worked backwards through it to find the element I needed to start with. How about the next one?'. When I get angry, Mr. Bigglesworth gets upset. ', After solving stage 3 you likely get the string 'Halfway there! The autograding service consists of four user-level programs that run, - Request Server (bomblab-requestd.pl). There exists a linked list structure under these codes. This count is checked by the function read six numbers which also takes the user input string and formats them into integers that are then dumped onto the stack. But finding it and solving it are quite different Here is Phase 4. Give 0 to ebp-4, which is used as sum of n0, n1, n2. It is passed the inputed user phrase and the pass-phrase and then checks that the two strings are the same length. Firstly, let's have a look at the asm code. What was the actual cockpit layout and crew of the Mi-24A? Have a nice day! 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_5 Contribute to CurryTang/bomb_lab_solution development by creating an account on GitHub. From the above annotations, we can see that there is a loop. After looking at these interesting strings, I'm going to make a few guesses at what is going on in this binary "BOMB!!". You won't be able, to validate the students handins. Then we can get the range of the first argument from the line. Here is Phase 5. The solution for the bomb lab of cs:app. Remember this structure from Phase 2? $ecx is the output of the loop, Values attached to letters based on testing: Congratulations! srveaw is pretty far off from abcdef. 3) The second parameter 'p' at the end of the loop must be equal with %ecx register. CSO1 - Bomb lab. If so, put zero in %eax and return. Each message contains a BombID, a phase, and an indication of the, event that occurred. readOK = sscanf(cString, "%d %d", &p, &q); --------------------------------------------------------. Please The "main daemon" starts and nannies the, request server, result server, and report deamon, ensuring that, exactly one of these processes (and itself) is running at any point in, time. False COVID-19 PCR Test. You get to know that the input sequence must be an arbitary combination of number 1,2,3,4,5,6. phase_6 Type "./makebomb.pl -h" to see its arguments. I know there has to be 6 numbers, with the range of 1-6, and there can't be any repeats. 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. Finally, we can see down at the bottom of the function that is being called after the contents of %eax and the fixed address 0x804980b have been pushed onto the stack. The second input had to be a 11, because the the phase_4 code did a simple compare, nothing special. Maybe you get an alternative string for the bomb blowing up if done so via the secret stage? Q. The answer is that the first input had to be 1. Thus, the second number in the series must be 1 greater than the first number, the third number in the series must be 2 larger than the second number, etc. The "report daemon" periodically, scans the scoreboard log file. It is called recursively and in the end you need it to spit out the number 11. phase_1() - I'm first going to start stepping through the program starting at main. Next it takes the address of the memory location within the array indexed by the third user input and places in the empty adjacent element designated by the second user input. Each element in the array has an empty element directly adjacent to it. This function reads 6 inputs to *(ebp-0x20)~*(ebp-0xc), use n0~n5 as their alias, and it compares 5 and n1 in 8049067, n1 must be larger than 5. which to blow yourself up. Thus, each student, gets a unique bomb that they must solve themselves. 0,1,2,3,4,5,6,7,8,9,10,11,12,13,14 I also found strings that look like they could be related to attribution: explode_bomb In order to determine the comparisons used, it will be useful to look up or know Jumps Based on Signed Comparisons. you like without losing any information. To review, open the file in an editor that reveals hidden Unicode characters. This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. (up to -6 points deducted) Each bomb explosion notification that reaches the staff results in a 1 point deduction, capped at -6 points total. We do this by typing, Then we request a bomb for ourselves by pointing a Web browser at, After saving our bomb to disk, we untar it, copy it to a host in the, approved list in src/config.h, and then explode and defuse it a couple, of times to make sure that the explosions and diffusion are properly, recorded on the scoreboard, which we check at, Once we're satisfied that everything is OK, we stop the lab, Once we go live, we type "make stop" and "make start" as often as we. . In the "offline" version, the. 1 Introduction. From the first few lines, we guess that there are two arguments to enter. Then enter this command. We can see one line above that $esi is also involved. Link to Bomb Lab Instructions (pdf) in GitHub Repository A tag already exists with the provided branch name. Could this mean alternative endings? I inputed the word 'blah' and continued to run the program. What are the advantages of running a power tool on 240 V vs 120 V? Is there a weapon that has the heavy property and the finesse property (or could this be obtained)? Here is Phase 6. Otherwise, the bomb explodes by printing " The other option for offering an offline lab is to use the, makebomb.pl script to build a unique quiet custom bomb for each, linux> ./makebomb.pl -i -s ./src -b ./bombs -l bomblab -u -v , This will create a quiet custom bomb in ./bombs/bomb for the. strings_not_equal() - This function implements the test of equality between the user inputed string and the pass-phrase for phase_1 of the bomb challenge. There was a problem preparing your codespace, please try again. There is an accessed memory area that serves as a counter. Breakpoints can be set at specific memory addresses, the start of functions, and line numbers. Each of you will work with a special "binary bomb". For, example, "-p abacba" will use variant "a" for phase 1, variant "b" for. The function then takes the address of the memory location within the array indexed by the second user input and places it in the empty adjacent element designated by the first user input. However, it. Now switch to Visual mode with v, cycle the print mode with p until you see the disassembled function, toggle your cursor with c, then finally move down to the movzx edx, byte . 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. To see the format of how we enter the six numbers, lets set a breakpoint at read_six_numbers. There are many things going on with shuffling of variables between registers, some bit shifting, and either a subtraction or an addition being applied to some of the hard coded constants. Looking for job perks? In memory there is a 16 element array of the numbers 0-15. We've made it very easy to run the service, but, some instructors may be uncomfortable with this requirement and will. Could there be a randomization of stages or two planned routes through the bomb? @cinos hi, I had same problem, I couldn't understand, I must have ecx 15 too, but I couldn't figure it out. Tools: Starting challenge; Phase_1: Phase_2: Phase_3: Phase_4: Phase_5: Phase_6: Bomb Lab Write-up. BOOM!!! read_six_numbers() - Checks that the user inputed at least 6 numbers and if less than 6 numbers then detonate the bomb. So you think you can stop the bomb with ctrl-c, do you? Learn more about bidirectional Unicode characters. Learn more about bidirectional Unicode characters, #######################################################, # Copyright (c) 2002-2013, R. Bryant and D. O'Hallaron, This directory contains the files that you will use to build and run, the CS:APP Bomb Lab. Increment %rdx by 1 to point to the next character byte and move to %eax. If not null terminated then preserve the originally passed pointer argument by copying it to %rdx. I choose the first argument as 1 and then the second one should be 311. OK. :-) 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." DrEvil. You signed in with another tab or window. enjoy another stunning sunset 'over' a glass of assyrtiko, English version of Russian proverb "The hedgehogs got pricked, cried, but continued to eat the cactus". Specifically: That's number 2. Many Git commands accept both tag and branch names, so creating this branch may cause unexpected behavior. sig_handler offline version, you can ignore most of these settings. CIA_MKUltraBrainwashing_Drugs . 1 first, so gdb is the most recent available version of GDB. Halfway there! (gdb) i r rax 0x603bf0 6306800 rbx 0x0 0 rcx 0xb 11 rdx 0x603bf0 6306800 rsi 0x1 1 rdi 0x603bf0 6306800 rbp 0x402140 0x402140 <__libc_csu_init> rsp 0x7fffffffdea8 0x7fffffffdea8 r8 0x60567c 6313596 r9 0x7ffff7fe8500 140737354040576 r10 0x7ffff7fe8500 140737354040576 r11 0x246 582 r12 0x400c00 4197376 r13 0x7fffffffdf90 140737488347024 r14 0x0 0 r15 0x0 0 rip 0x400e49 0x400e49 <phase_2> eflags . From phase_4, we call the four arguments of func4 to be a, b(known, 0), c(known, 14), d(known, 0). What is the Russian word for the color "teal"? We can get the full assembly code using an object dump: objdump -d path/to/binary > temp.txt. node4 So you got that one. The third bomb is about the switch expression. Each phase expects you to type a particular string on stdin. * See src/README for more information about the anatomy of bombs and, how they are constructed. Did the drapes in old theatres actually say "ASBESTOS" on them? Ok, let's get right to it and dig into the <phase_5> code: So, what have we got here? Then, we can take a look at the fixed value were supposed to match and go from there: Woah. phase_4 Many Git commands accept both tag and branch names, so creating this branch may cause unexpected behavior. Also run the command i r to see what the values of the variables are. Enter disas and you will get a chunk of assembly for the function phase_1 which we put our breakpoint at. start Your goal is to set breakpoints and step through the binary code using gdb to figure out the program inputs that defuse the bombs (and make you gain points). Considering this line of code. On a roll! Are you sure you want to create this branch? Phase 1 is sort of the "Hello World" of the Bomb Lab. How about the next one? Welcome to my fiendish little bomb. node6 I then restart the program and see if that got me through phase 1. Not the answer you're looking for? You don't need root access. So my understanding is that the first input is the starting point of the array, so it should be limited to between 0 and 14, and the second input is the sum of all the values that I visited starting from array[first input]. Phase 1. A tag already exists with the provided branch name. Any numbers entered after the first 6 can be anything. This commit does not belong to any branch on this repository, and may belong to a fork outside of the repository. In this repository I will take down my process of solving the bomb lab of CS:APP. At the . Mar 19, . If nothing happens, download GitHub Desktop and try again. And your students will have to get, (2) Starting the Bomb Lab. The Hardware/Software Interface - UWA @ Coursera. 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. As we have learned from the past phases, fixed values are almost always important. What' more, there's a function call to read_six_numbers(), we can inspect it, Up till now, you should be able to find out that in this part, we are required to enter six numbers. This commit does not belong to any branch on this repository, and may belong to a fork outside of the repository. Details on Grading for Bomb Lab. e = 16 Is there any extra credit for solving the secret phase. As an experienced engineer, I believe you can figure out that there are two arguments, each of which should be integers. What were the poems other than those by Donne in the Melford Hall manuscript? Up till now, there shouldn't be any difficulties. Maybe function names or labels? No description, website, or topics provided. Try this . There are various versions of this challenge scattered across . As a next step, lets input the test string abcdef and take a look at what the loop does to it. without any ill effects. To learn more, see our tips on writing great answers. Did the Golden Gate Bridge 'flatten' under the weight of 300,000 people in 1987? A string that could be the final string outputted when you solve stage 6 is 'Congratulations! You just choose a number arbitarily from 0 to 6 and go through the switch expression, and you get your second argument. If that function fails, it calls explode_bomb to the left. Thus on the 14th iteration if I needed a 6, I would need to be in the 14th index of the array on the 13th iteration, then on index 2 of the 12th iteration. Servers run quietly, so they. Then you set a breakpoint at 4010b3 and find the target string to be "flyers". Segmentation fault in attack lab phase5. A Mad Programmer got really mad and created a slew of binary bombs. Have a nice day! 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. changeme.edu Guide and work-through for System I's Bomb Lab at DePaul University. initialize_bomb_solve My phase 5 is different from most other phase 5's I've found online, as it is the input of two integers. Then you may not find the key to the second part(at least I didn't). je 0x40106a <phase_5+104> 0x0000000000401065 <+99>: callq 0x40163d <explode_bomb> ; explode_bomb . We can find the latter numbers from the loop structure. phase_6 This part is really long. Thus I'm pretty confident that this will be the pass phrase for the first phase. Load the binary, perform analysis, seek to Phase 6, and have a look at your task. The previous output from the strings program was outputted to stout in order that the strings are found in the binary.
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