CurryTang/bomb_lab_solution - Github Many Git commands accept both tag and branch names, so creating this branch may cause unexpected behavior. Control-l can be used to refresh the UI whenever it inevitably becomes distorted. Asking for help, clarification, or responding to other answers. In this exercise, we have a binary whose source we do not have. This command lists all the current breakpoints as well as how many times each breakpoint has been hit on the current run. I am currently stuck on bomb lab phase 5. Lets clear all our previous breakpoints and set a new one at phase_2. Thus, each student, gets a unique bomb that they must solve themselves. Servers run quietly, so they. You just pass through the function and it does nothing. so I did. There are two basic flavors of Bomb Lab: In the "online" version, the, instructor uses the autograding service to handout a custom notifying, bomb to each student on demand, and to automatically track their, progress on the realtime scoreboard. As a next step, lets input the test string abcdef and take a look at what the loop does to it. After solving stage 1 you likely get the string 'Phase 1 defused. How about the next one? Due to address randomization and nonexecutable stack, we are supposed to use Return Oriented Programming (ROP) to pass the string pointer of a given cookie value as argument to a function called touch3. We can see that the function is being called which as the name implies compares two strings. We get the following part, We see a critical keyword Border, right? Untar your specific file and lets get started! need to, but we are careful never to type "make cleanallfiles" again. A Mad Programmer got really mad and created a slew of binary bombs. 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). Lets set a breakpoint at strings_not_equal. It then updates the HTML scoreboard that summarizes, the current number of explosions and defusions for each bomb, rank. Entering these numbers allows us to pass phase_3. Identify the generic Linux machine ($SERVER_NAME) where you will, create the Bomb Lab directory (./bomblab) and, if you are offering the, online version, run the autograding service. In this version of the lab, you build your own quiet bombs manually, and then hand them out to the students. phase 2, variant "a" for phase 3, variant "c" for phase 4, and so on. Congratulations! Let's start with when it calls sym.read_six_numbers. This file is created by the report daemon, 4.4.4. To begin we first edit our gdbCfg file. Find centralized, trusted content and collaborate around the technologies you use most. In order to solve the cypher, take a look at %esi and youll find an array of characters stored there, where each character has an index. GitHub Microsoft is acquiring GitHub!Read our blog and Satya Nadella's post to learn more. The unique. Any numbers entered after the first 6 can be anything. blank_line Upon entry to that secret stage you likely get the string 'Curses, you've found the secret phase!' This works just fine, and I invite you to try it. Defusing the binary bomb. 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. The goal for the students is to defuse as many phases as possible. The Hardware/Software Interface - UWA @ Coursera. Firstly, let's have a look at the asm code. Answers that are vague, inaccurate, or . Then the tricky part comes. At the onset of the program you get the string 'Welcome to my fiendish little bomb. Phase 1 defused. The variable being used in this comparison is $eax. If that function fails, it calls explode_bomb to the left. a = 10 Readme (27 points) 2 points for explosion suppression, 5 points for each level question. This is the phase 5 of attack lab in my software security class. string_length() - This function first checks to see that the passed character pointer in %rdi is not null terminated. I also wanted to see groupings of strings that may have similar prefixes and so I sorted the strings program output and looked for anything interesting in that manner. There are a ton of dead ends that you can follow in this code that all land on detonation. You signed in with another tab or window. If nothing happens, download GitHub Desktop and try again. A tag already exists with the provided branch name. CMU Bomb Lab with Radare2 Phase 6 | by Mark Higgins - Medium Can you help me please? Binary Bomb Lab :: Phase 6. 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 . explode_bomb. 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. Binary-Bomb/phase2a.c at master lukeknowles/Binary-Bomb - Github This looks familiar! The key is to place the correct memory locations, as indexed by the user inputs, so as that the integer pointed to by the address is always greater than the preceding adjacent integer. In the interests of putting more Radare2 content out there, here's a noob friendly intro to r2 for those who already have a basic grasp of asm, C, and reversing in x86-64. phase_6 Thus, they quickly learn to set breakpoints before, each phase and the function that explodes the bomb. 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). Lo and behold, when we dump the contents of the memory address we get "%d", which tells us that the . $ecx is the output of the loop, Values attached to letters based on testing: 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. From this, we can guess that to pass phase_1, we need to enter the correct string. This continuous through all the user inputed indices and finally places the value zero in the last remaining empty element in the array. Lets create our breakpoints to make sure nothing gets set to the gradebook! Request Server: The request server is a simple special-purpose HTTP, server that (1) builds and delivers custom bombs to student browsers, on demand, and (2) displays the current state of the real-time, A student requests a bomb from the request daemon in two, steps: First, the student points their favorite browser at, For example, http://foo.cs.cmu.edu:15213/. Stepping through the code with the GDB debugger I can say plenty about the various functions called in this program: 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. Phase 1. At each iteration, we check to see that the current value is double the previous value. On whose turn does the fright from a terror dive end? Informal Explanations of Phases 1 through 6: I have spent approximately 26 hours on this assignment. bomblab-Angr/Phase 5 x86_64.ipynb. There are no explicit handins and the lab is self-grading. CIA_MKUltraBrainwashing_Drugs . ", Quiet Bomb: If compiled with the NONOTIFY option, then the bomb, doesn't send any messages when it explodes or is defused. I cannot describe the question better . In this write-up, I will show you how i solve bomb lab challenge. It is passed the inputed user phrase and the pass-phrase and then checks that the two strings are the same length. c = 1 As an experienced engineer, I believe you can figure out that there are two arguments, each of which should be integers. Assignment #3: Bomb Lab (due on Tue, Feb 21, 2023 by 11:59pm) Introduction. The idea is to understand what each, assembly statement does, and then use this knowledge to infer the, defusing string. 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. 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. The input should be "4 2 6 3 1 5". First bomb lab is a Reverse Engineering challenge, you have to read its assembly to find the message that . You signed in with another tab or window. You will get full credit for defusing phase 1 with less than 20 explosions. CMU Bomb Lab with Radare2 Phase 1. sc2225/Bomb-Lab - Github (sorted smallest to largest gives you the answer), See also: getSubSequenceCount Interview Question. The first number must be between 0 and 7. Lets use that address in memory and see what it contains as a string. What is the Russian word for the color "teal"? You signed in with another tab or window. A binary bomb is a program that consists of a sequence of six phases. When we hit phase_1, we can see the following code: The code is annotated with comments describing each line. I found various strings of interest. Next, as we scan through each operation, we see that a register is being . 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. In this repository I will take down my process of solving the bomb lab of CS:APP. offer the lab. Actually in this part, the answer isn't unique. In memory there is a 16 element array of the numbers 0-15. This command lists out all the values that each of the registers hold. sig_handler How about the next one? The LabID must not have any spaces. Although the problems differ from each other, the main methods we take are totally the same. Details on Grading for Bomb Lab. Enter a random string and then we stop at the phase 1 position, then we try printing out the information around 0x402400. phase_5 Software engineer at Amazon. CSO1 - Bomb lab - University of Virginia School of Engineering and Lets do the standard disas command to see the assembly of the function. Otherwise the bomb "explodes" by printing "BOOM!!!". On a roll! First you must enter two integers and the bomb will detonate if you enter more or less than that. Keep going! This commit does not belong to any branch on this repository, and may belong to a fork outside of the repository. If the student enters the expected string, then that phase. This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. The numbers you enter are used to sort a linked list actually. However, it. If the line is correct, then the phase is defused and the bomb proceeds to the next phase. Please You will only need, to modify or inspect a few variables in Section 1 of this file. On the other hand, custom quiet, Generic Bomb: A "generic bomb" has a BombID = 0, isn't associated with. servers running. I believe this function also acts as the gateway to the secret phase. We can find the latter numbers from the loop structure. DrEvil. Then enter this command. Thus the memory array contains an element that holds an integer followed by an element that holds a memory location from within the same array to one of the integers, followed by another integer, and then another memory location from within the array, etc, until the end of the array. to use Codespaces. invalid_phase I dereference the string pointed to by %rdi using x/s $rdi and see that the string pointed to is 'blah'. changeme.edu The user input is then, 4 5 1 6 2 3. Regardless, I'm not falling for it this time. rev2023.4.21.43403. Each message contains a BombID, a phase, and an indication of the, event that occurred. input.txt Public speaking is very easy. Please, Your answer could be improved with additional supporting information. Video on steps to complete phase one of the lab.If y'all real, hit that subscribe button lmao What I know so far: first input cannot be 15, 31, 47, etc. 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. * phase2a.c - To defeat this stage the user must enter a sequence of, * 6 nonnegative numbers where x[i] = x[i-1] + i. 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]. Going back all the way to the first iteration you needed to enter into the array at the 5th index, which is the first interger needed for the user input. If you solve the phase this way, youll actually notice that there is more than one correct solution. Since we know the final value is 6 letters/numbers, we know 72/6 = 12. Segmentation fault in attack lab phase5 - Stack Overflow If you are offering the. Then you can solve this problem by making a table(Yeah, it may seem silly, but I think it's the most convenient way). Content Discovery initiative April 13 update: Related questions using a Review our technical responses for the 2023 Developer Survey. [RE] Linux Bomb Walkthrough - Part2 (Phases 1-3) - [McB]Defence 1 2 6 24 120 720 0 q 777 9 opukma 4 2 6 3 1 5 output Welcome to my fiendish little bomb. Learn more about bidirectional Unicode characters. cse351/solution-explanation-of-phase-5.text at master - Github initialize_bomb_solve Are you sure you want to create this branch? Load the binary, perform analysis, seek to Phase 6, and have a look at your task. 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. "make stop" kills all of the running, servers. phase_3() - In this phase you are required to type in another code of at least 2 numbers. 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. Making statements based on opinion; back them up with references or personal experience. In order to determine the comparisons used, it will be useful to look up or know Jumps Based on Signed Comparisons. Each of you will work with a special "binary bomb". These look like they could pertain to the various phases of the bomb. I'll paste the code here. node3 When in doubt "make stop; make start" will get everything in a stable state. The code is comparing the string (presumably our input) stored in %eax to a fixed string stored at 0x804980b. Lets get started by creating both a breakpoint for explode_bomb and phase_2. mov a b moves data from a to b as opposed to b to a). Each line is annotated. Since there exists a bunch of different versions of this problem, I' ve already uploaded my version. offline version, you can ignore most of these settings. VASPKIT and SeeK-path recommend different paths. METU Ceng'e selamlar :)This is the first part of the Attack Lab. This command prints data stored at a register or memory address. The answer is that the first input had to be 1. How about saving the world? Cannot retrieve contributors at this time. - Main daemon (bomblab.pl). srveaw is pretty far off from abcdef. Here is Phase 6. After satisfying this first requirement of phase_5 there is a comparison of the second user input to what turns out to be the sum of the numbers in the array you accessed. 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. explode_bomb 0,1,2,3,4,5,6,7,8,9,10,11,12,13,14 Bomb Lab: Phase 5. 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. The dumb way is to simply input all characters from a-z into the cypher and create a mapping table. The third bomb is about the switch expression. Specifically: CMU Bomb Lab with Radare2 Phase 1 | by Mark Higgins - Medium node1 This commit does not belong to any branch on this repository, and may belong to a fork outside of the repository. Binary Bomb - Accolade Going back to the code for phase_2, we see that the first number has to be 1. So you think you can stop the bomb with ctrl-c, do you? What are the advantages of running a power tool on 240 V vs 120 V? read_six_numbers() - Checks that the user inputed at least 6 numbers and if less than 6 numbers then detonate the bomb. Have a nice day!' Phase 4: recursive calls and the stack discipline. and upon beating the stage you get the string 'Wow! Next, the, student fills in this form with their user name and email address, and, then submits the form. They will likely be either 'Good work! For example, after a function has finished executing, this command can be used to check the value of $rax to see the function output. Has depleted uranium been considered for radiation shielding in crewed spacecraft beyond LEO? Binary Bomb Lab :: Phase 6 - Zach Alexander 1) We have to find that number 'q' which will cause 12 (twelve) iterations. 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. phase_6 First things first, we can see from the call to at and subsequent jump equal statement our string should be six characters long. Bomb lab phase 4 string length. - sst.bibirosa.de Pretty confident its looking for 3 inputs this time. 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. You don't need root access. You create a table using the method above, and then you get the answer to be "ionefg". 'But finding it and solving it are quite different' Thinking of the func4 function, we put two lines together to see more clearly. The "report daemon" periodically, scans the scoreboard log file. 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. Actually I'm not that patient and I didn't go through this part on my own. phase_2() - This phase is about typing in a code. You encounter with a loop and you can't find out what it is doing easily. How a top-ranked engineering school reimagined CS curriculum (Ep. executable file 271 lines (271 sloc) 7.74 KB. 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. phase_1 Many Git commands accept both tag and branch names, so creating this branch may cause unexpected behavior. I choose the first argument as 1 and then the second one should be 311. Solution to OST2 Binary Bomb Lab. | by Olotu Praise Jah | Medium Each phase has a password/key that is solved through the hints found within the assembly code. Using layout asm, we can see the assembly code as we step through the program. You've defused the secret stage!'. can be started from initrc scripts at boot time. Phase 1 defused. Each bomb phase tests a different aspect of machine language programs: Phase 4: recursive calls and the stack discipline, Phases get progressively harder. The address and stuff will vary, but . First, interesting sections/function names: We can get the full assembly code using an object dump: objdump -d path/to/binary > temp.txt. 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. The second input had to be a 11, because the the phase_4 code did a simple compare, nothing special. Nothing special other than the first number acting like a selector of jump paths to a linked second number. The bomb explodes if the number calculated by this function does not equal 49. Many Git commands accept both tag and branch names, so creating this branch may cause unexpected behavior. you like without losing any information. I inputed the word 'blah' and continued to run the program. Curses, you've found the secret phase! Going through func4, we get the value of d at 400ff7 and 400fe2 to be (14 + 0) >> 1 = 7. Load the binary, perform analysis, seek to Phase 6, and have a look at your task. Each student gets a, bomb with a randomly chosen variant for each phase. Unexpected uint64 behaviour 0xFFFF'FFFF'FFFF'FFFF - 1 = 0? 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. On line <phase_4+16>, the <phase_4> function is pushing a fixed value stored at memory address 0x8049808 onto the stack right before a call to scanf is made. 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. What was the actual cockpit layout and crew of the Mi-24A? readOK = sscanf(cString, "%d %d", &p, &q); --------------------------------------------------------. The bomb has blown up. greatwhite.ics.cs.cmu.edu Many Git commands accept both tag and branch names, so creating this branch may cause unexpected behavior. 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). Is it true that the first input has to be 5, 21, 37, etc? We see that a strings_not_equal function is being called. You can start and stop the autograding service as often as. I'm getting a feeling that the author wants you to really have to work to get through some of these functions. Otherwise, the bomb explodes by printing "BOOM!! Increment %rdx by 1 to point to the next character byte and move to %eax. Have a nice day! Pull up the function in Graph mode with VV, press p to cycle between views, and select the minigraph. Let me know if you have any questions in the comments. Use arg1 and address ebp-0x20 as arguments of function read_six_numbers. This part is really long. Tools: Starting challenge; Phase_1: Phase_2: Phase_3: Phase_4: Phase_5: Phase_6: Bomb Lab Write-up. Ok, lets get right to it and dig into the code: So, what have we got here? frequency is a configuration variable in Bomblab.pm.
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