The Hardware/Software Interface - UWA @ Coursera. phase_4 From the first few lines, we guess that there are two arguments to enter. Going through func4, we get the value of d at 400ff7 and 400fe2 to be (14 + 0) >> 1 = 7. $ecx is the output of the loop, Values attached to letters based on testing: Binary Bomb Lab :: Phase 1 - Zach Alexander OK. :-) Each phase expects you to type a particular string on stdin.If you type the correct string, then the phase is defused and the bomb proceeds to the next phase. I see the output 'Phase 1 defused. phase_3 If the function succeeds, it follows the green arrow on the right to the third box. More than 2 is fine but the code is only dependent on the first two numbers. Then, we can take a look at the fixed value were supposed to match and go from there: Woah. These lines indicate that if the first argument equal the last one(right before this line), then we get 0. The second input had to be a 11, because the the phase_4 code did a simple compare, nothing special. The autograding service consists of four user-level programs that run, - Request Server (bomblab-requestd.pl). Help/Collaboration: I recieved no outside help with this bomb, other than. Wow! The answer is that the first input had to be 1. Now lets get started with Phase 1! What was the actual cockpit layout and crew of the Mi-24A? You continue to bounce through the array. BombID: Each bomb in a given instance of the lab has a unique, non-negative integer called the "bombID. Evil has created a slew of "binary bombs" for our class. If not null terminated then preserve the originally passed pointer argument by copying it to %rdx. Untar your specific file and lets get started! So, what do we know about phase 5 so far? Here are the directions for offering both versions of the lab. First, interesting sections/function names: The numbers you enter are used to sort a linked list actually. Try this . 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. Load the binary, perform analysis, seek to Phase 6, and have a look at your task. Contribute to hengyingchou/CSE351 development by creating an account on GitHub. frequency is a configuration variable in Bomblab.pm. This works just fine, and I invite you to try it. If one of these processes dies for some reason, the main daemon, detects this and automatically restarts it. If you are offering the online version, you will also need to edit the, ./src/config.h - This file lists the domain names of the hosts that, notifying bombs are allowed to run on. 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, --------------------------------------------------------------------------------. a user account on this machine. 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. There is also a test that the first user inputed number is less than or equal to 14. changeme.edu gdbCfg phase 5. The input should be "4 2 6 3 1 5". phase 2, variant "a" for phase 3, variant "c" for phase 4, and so on. Help with Binary Bomb Lab Phase 6 : r/learnprogramming - Reddit GitHub; Linkedin; Bomb Lab 7 minute read On this page. [RE] Linux Bomb Walkthrough - Part2 (Phases 1-3) - [McB]Defence because it is too easy for the students to cheat. (Add 16 each time) ecx is compared to rsp, which is 15, so we need ecx to equal to 15. Binary Bomb Lab :: Phase 5 - Zach Alexander We can see that our string input blah is being compared with the string Border relations with Canada have never been better.. Then you may not find the key to the second part(at least I didn't). Become familiar with Linux VM and Linux command-line, Use and navigate through gdb debugger to examine memory and registers, view assembly code, and set breakpoints within the gdb debugger, Read and understand low level assembly code. My phase 5 is different from most other phase 5's I've found online, as it is the input of two integers. phase_2 instructor builds, hands out, and grades the student bombs manually, While both version give the students a rich experience, we recommend, the online version. First, to figure out that the program wants a string as an input. This command prints data stored at a register or memory address. We can get the full assembly code using an object dump: objdump -d path/to/binary > temp.txt. I found: initialize_bomb This second phase deals with numbers so lets try to enter the array of numbers 0 1 2 3 4 5. to use Codespaces. Thanks for contributing an answer to Stack Overflow! If you solve the phase this way, youll actually notice that there is more than one correct solution. Next, the, student fills in this form with their user name and email address, and, then submits the form. This command lists out all the values that each of the registers hold. At the onset of the program you get the string '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. Considering this line of code. You signed in with another tab or window. A binary bomb is a program that consists of a sequence of phases. Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. Bomb explosions. CSAPP-Labs/README-bomblab at master - Github to use Codespaces. I dont want to go through either solution all the way here, since the first one is a no-brainer and the second one is a little complicated. 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. Each bomb phase tests a different aspect of machine language programs: Phase 4: recursive calls and the stack discipline, Phases get progressively harder. !", deducting points from your problem set grade, and then terminating. In memory there is a 16 element array of the numbers 0-15. A tag already exists with the provided branch name. In Bomb Lab phase_6, what are the appropriate steps to take after I The key is that each time you enter into the next element in the array there is a counter that increments. I will list some transitions here: The ascii code of "flyers" should be "102, 108, 121, 101, 114, 115". func4() - This function was rather difficult for me to get through logically and so I ultimately had to take it as somewhat as a black box. I have given a detailed explanation for phase_5 here: https://techiekarthik.hashnode.dev/cmu-bomblab-walkthrough?t=1676391915473#heading-phase-5. You will get full credit for defusing phases 2 and 3 with less than 30 explosions. phase_5 Nothing special other than the first number acting like a selector of jump paths to a linked second number. Solved this is binary bomb lab phase 5.I didn't solve phase - Chegg 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/. 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. Find centralized, trusted content and collaborate around the technologies you use most. GET /%s/submitr.pl/?userid=%s&lab=%s&result=%s&submit=submit HTTP/1.0 offline version, you can ignore most of these settings. 0,1,2,3,4,5,6,7,8,9,10,11,12,13,14 Each phase expects you to type a particular string. What is scrcpy OTG mode and how does it work? Let's have a look at the phase_4 function. Curses, you've found the secret phase! 0x00401100 4989e5 mov r13, rsp. Link to Bomb Lab Instructions (pdf) in GitHub Repository Entering these numbers allows us to pass phase_3. Then you can solve this problem by making a table(Yeah, it may seem silly, but I think it's the most convenient way). 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. 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. Lets use blah again as out input for phase_2. phase_4() - In this phase you are dealing with a recursively called function. 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. initialize_bomb And your students will have to get, (2) Starting the Bomb Lab. Each of you will work with a special "binary bomb". In this version of the lab, you build your own quiet bombs manually, and then hand them out to the students. A string that could be the final string outputted when you solve stage 6 is 'Congratulations! This commit does not belong to any branch on this repository, and may belong to a fork outside of the repository. Many Git commands accept both tag and branch names, so creating this branch may cause unexpected behavior. Mar 19, . CMU Bomb Lab with Radare2 Phase 5 | by Mark Higgins - Medium As we can see, it is fairly obvious that there is a loop somewhere in this function (by following the arrows). Can you help me please? * phase2a.c - To defeat this stage the user must enter a sequence of, * 6 nonnegative numbers where x[i] = x[i-1] + i. Well solution to each bomb is available to the instructor. Using layout asm, we can see the assembly code as we step through the program. We can see that the function is being called which as the name implies compares two strings. Increment %rdx by 1 to point to the next character byte and move to %eax. I also found strings that look like they could be related to attribution: CMU Bomb Lab with Radare2 Phase 1. ", Quiet Bomb: If compiled with the NONOTIFY option, then the bomb, doesn't send any messages when it explodes or is defused. I keep on getting like 3 numbers correctly, and then find the only possible solutions for the other 3 incorrect, so I am at a loss. Solve a total of 6 phases to defuse the bomb. 565), Improving the copy in the close modal and post notices - 2023 edition, New blog post from our CEO Prashanth: Community is the future of AI. Once you have updated the configuration files, modify the Latex lab, writeup in ./writeup/bomblab.tex for your environment. GitHub - Taylor1VT/HW-5-Binary-Bomb Not the answer you're looking for? To subscribe to this RSS feed, copy and paste this URL into your RSS reader. Based on the output, our input string is being run into the function with the string I can see Russia from my . This commit does not belong to any branch on this repository, and may belong to a fork outside of the repository. 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". The second input had to be a 11, because the the phase_4 code did a simple compare, nothing special. If you notice, (the syntax will vary based off of what sort of system the bomb is run on) the machine code will have some variation of call to: 401135: be b8 25 40 00 mov $0x4025b8,%esi. 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 in doubt "make stop; make start", However, resetting the lab deletes all old bombs, status logs, and the, scoreboard log. Pretty confident its looking for 3 inputs this time. Are you sure you want to create this branch? The request server, responds by sending an HTML form back to the browser. phase_4 I think the second number should be. Option 1: The simplest approach for offering the offline Bomb Lab is. Remember this structure from Phase 2? func4 ??? Maybe you get an alternative string for the bomb blowing up if done so via the secret stage? to build a single generic bomb that every student attempts to defuse: This will create a generic bomb and some other files in ./bombs/bomb0: bomb* Generic bomb executable (handout to students), bomb.c Source code for main routine (handout to students), You will handout only two of these files to the students: ./bomb and ./bomb.c, The students will handin their solution files, which you can validate, This option is easy for the instructor, but we don't recommend it. The bomb explodes if the number calculated by this function does not equal 49. Each student gets a, bomb with a randomly chosen variant for each phase. * Before going live with the students, we like to check everything out, by running some tests. We get the following part, We see a critical keyword Border, right? Phase 1. . Please It's provided only for completeness. Jumping to the next "instruction" using gdb, Binary Bomb Phase 5 issue (my phase 5 seems to be different from everyone elses), Memory allocation and addressing in Assembly, Tikz: Numbering vertices of regular a-sided Polygon. Solution to OST2 Binary Bomb Lab. | by Olotu Praise Jah | Medium Good work! phase_2 Then we can get the range of the first argument from the line. CMU Bomb Lab with Radare2 Phase 6 | by Mark Higgins - Medium The "report daemon" periodically, scans the scoreboard log file. I dereference the string pointed to by %rdi using x/s $rdi and see that the string pointed to is 'blah'. initialize_bomb_solve We can now see the assembly code. The variable being used in this comparison is $eax. This commit does not belong to any branch on this repository, and may belong to a fork outside of the repository. First thing I did was to search the binary using strings to see if there was anything interesting that pops out. If you type the correct string, then. 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. You signed in with another tab or window. e = 16 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. Lets create our breakpoints to make sure nothing gets set to the gradebook! As an experienced engineer, I believe you can figure out that there are two arguments, each of which should be integers. Each offering of the Bomb Lab starts with a clean new ./bomblab. When prompted, enter the command 'c' to continue. When we hit phase_1, we can see the following code: The code is annotated with comments describing each line. ordered by the total number of accrued points. Cannot retrieve contributors at this time. Then you set a breakpoint at 4010b3 and find the target string to be "flyers". Alternative paths? initialize_bomb Many Git commands accept both tag and branch names, so creating this branch may cause unexpected behavior. This file is created by the report daemon, 4.4.4. Use Git or checkout with SVN using the web URL. Thus I'm pretty confident that this will be the pass phrase for the first phase. So there are some potential strings for solving each of the stages. CS107 Assignment 5: Binary bomb - Stanford University It is useful to check the values of these registers before/after entering a function. Binary Bomb Lab :: Phase 4 - Zach Alexander 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. Details on Grading for Bomb Lab. I found various strings of interest. 1) We have to find that number 'q' which will cause 12 (twelve) iterations. 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. 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. GitHub Microsoft is acquiring GitHub!Read our blog and Satya Nadella's post to learn more. You don't need to understand any of this to. phase_defused. d = 12 Try this one. Which one to choose? This commit does not belong to any branch on this repository, and may belong to a fork outside of the repository. The students work on defusing, their bombs offline (i.e., independently of any autograding service), and then handin their solution files to you, each of which you grade, You can use the makebomb.pl script to build your own bombs. The third bomb is about the switch expression. What does the power set mean in the construction of Von Neumann universe? I then restart the program and see if that got me through phase 1. @Jester so I looked at your reply to another question which is extremely similar to my question, actually the same exact question. Are you sure you want to create this branch? Any numbers entered after the first 6 can be anything. node5 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. Give 0 to ebp-4, which is used as sum of n0, n1, n2. I will omit this part here, you can refer to this document. If so, pass the counter back to the calling function else continue the incrementing loop through string pointer until it hits null termination. Breakpoints can be set at specific memory addresses, the start of functions, and line numbers. lesson and forces them to learn to use a debugger. Segmentation fault in attack lab phase5. These numbers act as indices within a six element array in memory, each element of which contains a number. Q. You can enter any string, but I used TEST. Contribute to xmpf/cse351 development by creating an account on GitHub. Phase 1 defused. Stepping through the code with the GDB debugger I can say plenty about the various functions called in this program: Control-l can be used to refresh the UI whenever it inevitably becomes distorted. Given you ultimately needed to have the element containing 0xf to exit after 15 iterations, I saw that f was at array element index 6. The key part is the latter one. But when I put 4 1 6 5 2 3 or 3 6 1 2 5 4, it explodes. Load the binary, perform analysis, seek to Phase 6, and have a look at your task. 1 first, so gdb is the most recent available version of GDB. Next there is pattern that must be applied to the first 6 numbers. I choose the first argument as 1 and then the second one should be 311. phase_5() - This function requires you to go backwards through an array of numbers to crack the code. executable file 271 lines (271 sloc) 7.74 KB. Many Git commands accept both tag and branch names, so creating this branch may cause unexpected behavior. We've made it very easy to run the service, but, some instructors may be uncomfortable with this requirement and will. without any ill effects. Is it true that the first input has to be 5, 21, 37, etc? Entering this string defuses phase_1. After looking at these interesting strings, I'm going to make a few guesses at what is going on in this binary "BOMB!!". For, example, "-p abacba" will use variant "a" for phase 1, variant "b" for. 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. * See src/README for more information about the anatomy of bombs and, how they are constructed. 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. 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. A tag already exists with the provided branch name. Is there a weapon that has the heavy property and the finesse property (or could this be obtained)? You'll only need to have. Link to Bomb Lab Instructions (pdf) in GitHub Repository. You've defused the secret stage! 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. Enter disas and you will get a chunk of assembly for the function phase_1 which we put our breakpoint at. I'm guessing that this function will likely compare the string that I inputed to some string stored in memory somewhere. Each binary bomb is a program, running a sequence of phases. The first number must be between 0 and 7. When in doubt "make stop; make start" will get everything in a stable state. Asking for help, clarification, or responding to other answers. je 0x40106a <phase_5+104> 0x0000000000401065 <+99>: callq 0x40163d <explode_bomb> ; explode_bomb . 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. From this, we can deduce that the input for phase_2 should be 1 2 4 8 16 32. To learn more, see our tips on writing great answers. A loop is occurring. Next, as we scan through each operation, we see that a register is being . Many Git commands accept both tag and branch names, so creating this branch may cause unexpected behavior. this is binary bomb lab phase 5.I didn't solve phase 5. First, the numbers must be positive. any particular student, is quiet, and hence can run on any host. I tried many methods of solution on internet. You get to know that the input sequence must be an arbitary combination of number 1,2,3,4,5,6. greatwhite.ics.cs.cmu.edu 3) The second parameter 'p' at the end of the loop must be equal with %ecx register. Analysis of CME bomb lab program in linux using dbg, objdump, and strings. (sorted smallest to largest gives you the answer), See also: getSubSequenceCount Interview Question. CIA_MKUltraBrainwashing_Drugs . 'But finding it and solving it are quite different' Bomb Lab Write-up. This post walks through the first 3 phases of the lab. node6 sign in readOK = sscanf(cString, "%d %d", &p, &q); --------------------------------------------------------. 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 Bomb Lab teaches students principles of, machine-level programs, as well as general debugger and reverse, A "binary bomb" is a Linux executable C program that consists of six, "phases." 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. When you fail a phase, and the bomb goes off, you probably get the string 'BOOM!!!' The code must be at least six numbers long or else the bomb detonates. Halfway there! can be started from initrc scripts at boot time. Bomb lab phase 6 github - ayafpo.saligia-kunst.de Upon entry to that secret stage you likely get the string 'Curses, you've found the secret phase!' Instructors and students view the scoreboard by pointing their, The online Bomb Lab is self-grading. All things web. 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). phase_4 Analysis of Binary Bomb Lab GitHub It is passed the inputed user phrase and the pass-phrase and then checks that the two strings are the same length. No description, website, or topics provided. Did the drapes in old theatres actually say "ASBESTOS" on them?
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