To review, open the file in an editor that reveals hidden Unicode characters. The second input had to be a 11, because the the phase_4 code did a simple compare, nothing special. As the students work on their bombs, each, explosion and defusion is streamed back to the server, where the, current results for each bomb are displayed on a Web "scoreboard.". Keep going! Did the drapes in old theatres actually say "ASBESTOS" on them? Many Git commands accept both tag and branch names, so creating this branch may cause unexpected behavior. 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. First things first, we can see from the call to <string_length> at <phase_5+23> and subsequent jump equal statement our string should be six characters long. It first checks that you have inputed 6 numbers, then that they are within the range of 1 through 6, and finally that they are all unique numbers, in that no number is repeated. When I get angry, Mr. Bigglesworth gets upset. Many Git commands accept both tag and branch names, so creating this branch may cause unexpected behavior. Learn more. Here is Phase 3. The key part is the latter one. How does loop address alignment affect the speed on Intel x86_64? I tried many methods of solution on internet. phase_defused What are the advantages of running a power tool on 240 V vs 120 V? To review, open the file in an editor that reveals hidden Unicode characters. Binary Bomb Lab :: Phase 4 - Zach Alexander The code shows as follows: After inspecting the code, you should figure out that the length of the string must be 6. 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. So, what do we know about phase 5 so far? Please, Your answer could be improved with additional supporting information. Instructors and students view the scoreboard by pointing their, The online Bomb Lab is self-grading. Control-l can be used to refresh the UI whenever it inevitably becomes distorted. Bomb lab phase 4 string length. - sst.bibirosa.de The bomb explodes if the number calculated by this function does not equal 49. which to blow yourself up. It then updates the HTML scoreboard that summarizes, the current number of explosions and defusions for each bomb, rank. I think the second number should be. Run the following commands to create text files which we will look at later: You should now have two files: strings.txt and assembly.txt. Segmentation fault in attack lab phase5. Lets now set a breakpoint at phase_3. Nothing special other than the first number acting like a selector of jump paths to a linked second number. You will handout four of these files to the student: bomb, bomb.c, ID, Each student will hand in their solution file, which you can validate. Additional Notes on the Online Bomb Lab, * Since the request server and report daemon both need to execute, bombs, you must include $SERVER_NAME in the list of legal machines in, * All of the servers and daemons are stateless, so you can stop ("make, stop") and start ("make start") the lab as many times as you like. This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. First things first, we can see from the call to at and subsequent jump equal statement our string should be six characters long. Next there is pattern that must be applied to the first 6 numbers. There are 6 levels in the bomb and our task is to diffuse it. It's provided only for completeness. Moreover, it's obvious that the second one must be zero being aware of the line, So the problem becomes easier. Ok, lets get right to it and dig into the code: So, what have we got here? It is useful to check the values of these registers before/after entering a function. I found various strings of interest. It's obvious that the first number should be 1. From here, we have two ways to solve this phase, a dumb way and a smart way. DrEvil. This works just fine, and I invite you to try it. Remember this structure from Phase 2? GET /%s/submitr.pl/?userid=%s&lab=%s&result=%s&submit=submit HTTP/1.0 Here is Phase 6. From this, we can deduce that the input for phase_2 should be 1 2 4 8 16 32. This looks just like phase 1. Wow! How about the next one? Video on steps to complete phase one of the lab.If y'all real, hit that subscribe button lmao node1 Guide and work-through for System I's Bomb Lab at DePaul University. The bomb explodes if the number of steps to get to the number 15 in the sequence does not equal 9, or if the second input number does not equal the sum of the . readOK = sscanf(cString, "%d %d", &p, &q); --------------------------------------------------------. A tag already exists with the provided branch name. Good work! 3 lea's, a cmp of the output to 2 and a jump if greater than. Load the binary, perform analysis, seek to Phase 6, and have a look at your task. changeme.edu This continuous through all the user inputed indices and finally places the value zero in the last remaining empty element in the array. CS107 Assignment 5: Binary bomb - Stanford University node2 phase_5 There is an accessed memory area that serves as a counter. In this repository I will take down my process of solving the bomb lab of CS:APP. CurryTang/bomb_lab_solution - Github For example, after a function has finished executing, this command can be used to check the value of $rax to see the function output. because it is too easy for the students to cheat. Any numbers entered after the first 6 can be anything. !", deducting points from your problem set grade, and then terminating. Making statements based on opinion; back them up with references or personal experience. A Mad Programmer got really mad and created a slew of binary bombs. not 0, 1, 5, 6, 7, 8, 9, 10, 11, 12, 898, 1587, number is between 0 and 14 using comparison statement Each phase expects you to type a particular string on stdin. You can start and stop the autograding service as often as. Welcome to my fiendish little bomb. Then we take a look at the assembly code above, we see one register eax and an address 0x402400. I choose the first argument as 1 and then the second one should be 311. This commit does not belong to any branch on this repository, and may belong to a fork outside of the repository. At the . bomblab-Angr/Phase 5 x86_64.ipynb. phase_5 () - This function requires you to go backwards through an array of numbers to crack the code. To begin we first edit our gdbCfg file. I inputed the word 'blah' and continued to run the program. If this is a duplicate of another question, please link it so future readers can find it if their search turns up this question first. We've made it very easy to run the service, but, some instructors may be uncomfortable with this requirement and will. Then, we can take a look at the fixed value were supposed to match and go from there: Woah. If the event was a defusion, the message also, contains the "defusing string" that the student typed to defuse the, Report Daemon: The report daemon periodically scans the scoreboard log, and updates the Web scoreboard. You'll only need to have. Lo and behold, when we dump the contents of the memory address we get "%d", which tells us that the . Phase 1 is sort of the "Hello World" of the Bomb Lab. There are various versions of this challenge scattered across . Connect and share knowledge within a single location that is structured and easy to search. Find centralized, trusted content and collaborate around the technologies you use most. They will likely be either 'Good work! No description, website, or topics provided. executable file 271 lines (271 sloc) 7.74 KB. But finding it and solving it are quite different As we can see, it is fairly obvious that there is a loop somewhere in this function (by following the arrows). It is passed the inputed user phrase and the pass-phrase and then checks that the two strings are the same length. A tag already exists with the provided branch name. Contribute to xmpf/cse351 development by creating an account on GitHub. Upon entry to that secret stage you likely get the string 'Curses, you've found the secret phase!' Cannot retrieve contributors at this time. srveaw is pretty far off from abcdef. Otherwise, the bomb explodes by printing "BOOM!! CSO1 - Bomb lab. We can see that the last line shouldn't be contained in this switch structure, while the first four should be. To see the format of how we enter the six numbers, lets set a breakpoint at read_six_numbers. Binary Bomb Lab :: Phase 5 - Zach Alexander 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]. (up to -6 points deducted) Each bomb explosion notification that reaches the staff results in a 1 point deduction, capped at -6 points total. That's number 2. When, the student untars this file, it creates a directory (./bomb) with, bomb* Notifying custom bomb executable, bomb.c Source code for the main bomb routine, ID Identifies the student associated with this bomb, README Lists bomb number, student, and email address, The request server also creates a directory (bomblab/bombs/bomb), bomb.c Source code for main routine, bomb-quiet* A quiet version of bomb used for autograding, ID Identifies the user name assigned to this bomb, phases.c C source code for the bomb phases, README Lists bombID, user name, and email address, Result Server: Each time a student defuses a phase or explodes their, bomb, the bomb sends an HTTP message (called an autoresult string) to, the result server, which then appends the message to the scoreboard, log. is "defused." Each message contains a BombID, a phase, and an indication of the, event that occurred. This file is created by the report daemon, 4.4.4. If you type the correct string, then. Interpreting non-statistically significant results: Do we have "no evidence" or "insufficient evidence" to reject the null? Each student gets a, bomb with a randomly chosen variant for each phase. Lets create our breakpoints to make sure nothing gets set to the gradebook! Essentially what is happening is, each character from our string is ANDed with 0xf, and the result is used to get the character with the corresponding index from the array. 10 January 2015. secret_phase !!! The previous output from the strings program was outputted to stout in order that the strings are found in the binary. A loop is occurring. 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. Each time a student defuses a, bomb phase or causes an explosion, the bomb sends a short HTTP, message, called an "autoresult string," to an HTTP "result server,", which simply appends the autoresult string to a "scoreboard log file. If one of these processes dies for some reason, the main daemon, detects this and automatically restarts it. I dereference the string pointed to by %rdi using x/s $rdi and see that the string pointed to is 'blah'. daemon that starts and nannies the other programs in the service, checking their status every few seconds and restarting them if, (3) Stopping the Bomb Lab. ', After solving stage 2, you likely get the string 'That's number 2. I should say the first half of the code is plain. Ultimately to pass this test all you need to do is input any string of 46 characters in length that does not start with a zero. Custom, notifying bombs are constrained to run on a specific set of Linux, hosts determined by the instructor. The smart way of solving this phase is by actually figuring out the cypher. GitHub; Linkedin; Bomb Lab 7 minute read On this page. ', It is not clear what may be the output string for solving stage 4 or 5. Phase 1 defused. * Before going live with the students, we like to check everything out, by running some tests. Here are a few useful commands that are worth highlighting: This command divides the screen into two parts: the command console and a graphical view of the assembly code as you step through it. initialize_bomb Subtract original pointer from %eax and get the running total of the string. our input has to be a string of 6 characters, the function accepts this 6 character string and loops over each character in it, the result of the loop is compared to a fixed string, and if theyre equal, the bomb doesnt explode. Work fast with our official CLI. Can you help me please? Solution to OST2 Binary Bomb Lab. | by Olotu Praise Jah | Medium invalid_phase It is important to step the test numbers in some way so you know which order they are in. So you got that one. * phase2a.c - To defeat this stage the user must enter a sequence of, * 6 nonnegative numbers where x[i] = x[i-1] + i. Binary Bomb Lab (All Phases Solved) - John Keller This post walks through CMUs bomb lab, which involves defusing a bomb by finding the correct inputs to successive phases in a binary executable using GDB. If not then the detonation flag that was initialized to 1 is not set to low and will eventually trigger the detonate function. by hand by running their custom bomb against their solution: For both Option 1 and Option 2, the makebomb.pl script randomly, chooses the variant ("a", "b", or "c") for each phase. There are a ton of dead ends that you can follow in this code that all land on detonation. The student then saves the tar file to disk. It also might be easier to visualize the operations by using an online disambler like https://onlinedisassembler.com/ to see a full graph. correctly, else you and your students won't be able to run your bombs. Not the answer you're looking for? More than 2 is fine but the code is only dependent on the first two numbers. phase_3() - In this phase you are required to type in another code of at least 2 numbers. Please, Understanding Bomb Lab Phase 5 (two integer input), https://techiekarthik.hashnode.dev/cmu-bomblab-walkthrough?t=1676391915473#heading-phase-5. Since we know the final value is 6 letters/numbers, we know 72/6 = 12. Binary Bomb Lab :: Phase 1 - Zach Alexander It should look like this. I'll paste the code here. Each phase has a password/key that is solved through the hints found within the assembly code. I know there has to be 6 numbers, with the range of 1-6, and there can't be any repeats. Asking for help, clarification, or responding to other answers. Many Git commands accept both tag and branch names, so creating this branch may cause unexpected behavior. sign in Bomb Lab - 0x70RVS So, the value of node1 to node6 are f6, 304, b7, eb, 21f, 150. First, interesting sections/function names: 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. Looks like it wants 2 numbers and a character this time. So you think you can stop the bomb with ctrl-c, do you?' When we hit phase_1, we can see the following code: 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. There are six of them but some of these could be just added strings outputted upon completion of a stage. Problem set 2 - CS 61 2021 - Harvard University phase_4 A tag already exists with the provided branch name. From the above annotations, we can see that there is a loop. Solved this is binary bomb lab phase 5.I didn't solve phase - Chegg The key is that each time you enter into the next element in the array there is a counter that increments. we use, and get the following file (not the full code), We enter gdb, set a breakpoint at the phase 1. What is scrcpy OTG mode and how does it work? Tools: Starting challenge; Phase_1: Phase_2: Phase_3: Phase_4: Phase_5: Phase_6: Bomb Lab Write-up. Many Git commands accept both tag and branch names, so creating this branch may cause unexpected behavior. 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. Do this when you're ready for the lab to go "live" to, Resetting is also useful while you're preparing the lab. In addition, most, phase variants are parameterized by randomly chosen constants that are, assigned when a particular bomb is constructed. Phase 2: loops. This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. This commit does not belong to any branch on this repository, and may belong to a fork outside of the repository. While layout asm is helpful, also helpful to view the complete disassembled binary. This is the phase 5 of attack lab in my software security class. e = 16 The second input had to be a 11, because the the phase_4 code did a simple compare, nothing special. 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. Each phase expects the student to enter a particular string, on stdin. In the "offline" version, the. I'm guessing that this function will likely compare the string that I inputed to some string stored in memory somewhere. (**Please feel free to fork or star if helpful!). This commit does not belong to any branch on this repository, and may belong to a fork outside of the repository. (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 . Score!!! Use arg1 and address ebp-0x20 as arguments of function read_six_numbers. 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, --------------------------------------------------------------------------------. If so, put zero in %eax and return. If not null terminated then preserve the originally passed pointer argument by copying it to %rdx. ordered by the total number of accrued points. Then we use strings command to find out the answer, Having a look at the code structure, you should notice that there exists a loop structure. The numbers you enter are used to sort a linked list actually. If you accidentally kill one of the daemons, or you modify a daemon, or the daemon dies for some reason, then use, "make stop" to clean up, and then restart with "make start". By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. 1 first, so gdb is the most recent available version of GDB. your answer turns out to be 21 115, The solution is : 5 115. The answer is that the first input had to be 1. Help with Binary Bomb Lab Phase 6 : r/learnprogramming - Reddit this is binary bomb lab phase 5.I didn't solve phase 5. Although the problems differ from each other, the main methods we take are totally the same. Have a nice day!' Many Git commands accept both tag and branch names, so creating this branch may cause unexpected behavior. CMU Bomb Lab with Radare2 Phase 5 | by Mark Higgins - Medium solution to each bomb is available to the instructor. To learn more, see our tips on writing great answers. 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. In order to defuse the bomb, students must use a debugger, typically, gdb or ddd, to disassemble the binary and single-step through the, machine code in each phase. Answers that are vague, inaccurate, or . VASPKIT and SeeK-path recommend different paths. This series will focus on CMU's Binary Bomb challenge. You encounter with a loop and you can't find out what it is doing easily. Well This commit does not belong to any branch on this repository, and may belong to a fork outside of the repository. Bomb_Lab/Analysis.md at master MarkHyphen/Bomb_Lab GitHub My phase 5 is different from most other phase 5's I've found online, as it is the input of two integers. offer the lab. The third bomb is about the switch expression. Give 0 to ebp-4, which is used as sum of n0, n1, n2. Entering this string defuses phase_1. . On a roll! Are you sure you want to create this branch? Have a nice day! Try this one. (sorted smallest to largest gives you the answer), See also: getSubSequenceCount Interview Question. Browse other questions tagged, Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide. The request server parses the form, builds and, tars up a notifying custom bomb with bombID=n, and delivers the tar, file to the browser. Are you sure you want to create this branch? Using layout asm, we can see the assembly code as we step through the program. read_six_numbers Option 1: The simplest approach for offering the offline Bomb Lab is. phase_2 However, you know that the loop is doing some transitions on your input string. The main daemon is the. 0x00401100 4989e5 mov r13, rsp. Bomb Lab: Phase 5. Phase 1 defused. So you got that one. "make cleanallfiles" resets the lab from scratch, deleting all data specific to a particular instance of the lab, such, as the status log, all bombs created by the request server, and the, scoreboard log. . It appears that there may be a secret stage. There was a problem preparing your codespace, please try again. Let's start with when it calls sym.read_six_numbers. The goal for the students is to defuse as many phases as possible. Second, each progressive number in the code series entered by the user must be 1 larger than the next. ", - Report Daemon (bomblab-reportd.pl). Such bombs are called "notifying bombs. I also found strings that look like they could be related to attribution: Mar 19, . Did the Golden Gate Bridge 'flatten' under the weight of 300,000 people in 1987? These numbers act as indices within a six element array in memory, each element of which contains a number. Keep going! A binary bomb is a program that consists of a sequence of six phases. Then enter this command. requires that you keep the autograding service running non-stop, because handouts, grading, and reporting occur continuously for the, duration of the lab. At the onset of the program you get the string 'Welcome to my fiendish little bomb. CMU Bomb Lab with Radare2 Phase 6 | by Mark Higgins - Medium to use Codespaces. You've defused the secret stage!'. A tag already exists with the provided branch name. input.txt Public speaking is very easy. Going through func4, we get the value of d at 400ff7 and 400fe2 to be (14 + 0) >> 1 = 7. How about the next one? The request server also creates a copy of the bomb and its, - Result Server (bomblab-resultd.pl). CSAPP-Labs/README-bomblab at master - Github

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