VASPKIT and SeeK-path recommend different paths. I will omit this part here, you can refer to this document. Lets use that address in memory and see what it contains as a string. This works just fine, and I invite you to try it. How is white allowed to castle 0-0-0 in this position? My phase 5 is different from most other phase 5's I've found online, as it is the input of two integers. I then continue to run the program until I am prompted for a phrase to input. phase_defused() - So this function implements stack protection by adding, checking, and removing a canary. Then we encounter with an optimized switch expression. That's number 2. Maybe function names or labels? So far from my understanding, two conditions need to be met: edx must equal 0xf, meaning the first input has to be 5, 21, 37, etc. 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. 1) We have to find that number 'q' which will cause 12 (twelve) iterations. 'But finding it and solving it are quite different' readOK = sscanf(cString, "%d %d", &p, &q); --------------------------------------------------------. Specifically: rev2023.4.21.43403. From this mapping table, we can figure out the un-cyphered version of giants. Students earn points for defusing phases, and they, lose points (configurable by the instructor, but typically 1/2 point), for each explosion. c = 1 Welcome to my fiendish little bomb. These numbers act as indices within a six element array in memory, each element of which contains a number. 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. to use Codespaces. f = 9. For homework: defuse phases 2 and 3. You signed in with another tab or window. The first argument must be less than 7, right? 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. A clear, concise, correct answer will earn full credit. The previous output from the strings program was outputted to stout in order that the strings are found in the binary. Explosion and, diffusions from bombs whose LabIDs are different from the current. Informal Explanations of Phases 1 through 6: I have spent approximately 26 hours on this assignment. CMU Bomb Lab with Radare2 Phase 1. The binary bomb is a very good exercise to learn the assembly language.I started this exercise for fun. The dumb way is to simply input all characters from a-z into the cypher and create a mapping table. PHASE 3. Interpreting non-statistically significant results: Do we have "no evidence" or "insufficient evidence" to reject the null? The address and stuff will vary, but . Cannot retrieve contributors at this time. 1 Introduction. phase_3() - In this phase you are required to type in another code of at least 2 numbers. phase_3 On a roll! Based on the first user inputed number, you enter into that indexed element of the array, which then gives you the index of the next element in the array, etc. You've defused the bomb!'. not 0, 1, 5, 6, 7, 8, 9, 10, 11, 12, 898, 1587, number is between 0 and 14 using comparison statement phase_1 (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 . The idea is to understand what each, assembly statement does, and then use this knowledge to infer the, defusing string. First, to figure out that the program wants a string as an input. "make stop" kills all of the running, servers. The smart way of solving this phase is by actually figuring out the cypher. 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, --------------------------------------------------------------------------------. Connect and share knowledge within a single location that is structured and easy to search. I think the second number should be. . offer the lab. You signed in with another tab or window. It is important to step the test numbers in some way so you know which order they are in. You will get full credit for defusing phase 1 with less than 20 explosions. Congratulations! I found various strings of interest. node6 The first number we can try to be 6 and the second must be 682. srveaw is pretty far off from abcdef. The code shows as follows: After inspecting the code, you should figure out that the length of the string must be 6. 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. By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. The update. There are no explicit handins and the lab is self-grading. From the first few lines, we guess that there are two arguments to enter. 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. Then you may not find the key to the second part(at least I didn't). 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. b = 6 phase 2, variant "a" for phase 3, variant "c" for phase 4, and so on. So, the value of node1 to node6 are f6, 304, b7, eb, 21f, 150. Are you sure you want to create this branch? Let's start with when it calls sym.read_six_numbers. phase_4() - In this phase you are dealing with a recursively called function. Learn more. We can see that the last line shouldn't be contained in this switch structure, while the first four should be. Then enter this command. Also, where the arrow is, it's comparing the current node with the next node. Many Git commands accept both tag and branch names, so creating this branch may cause unexpected behavior. 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". phase_2 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. This command prints data stored at a register or memory address. Can you help me please? I know there has to be 6 numbers, with the range of 1-6, and there can't be any repeats. 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. Unexpected uint64 behaviour 0xFFFF'FFFF'FFFF'FFFF - 1 = 0? Each message contains a BombID, a phase, and an indication of the, event that occurred. Try this one.'. Alternative paths? 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. Then type the, This will create ps and pdf versions of the writeup, (1) Reset the Bomb Lab from scratch by typing, (2) Start the autograding service by typing, (3) Stop the autograding service by typing, You can start and stop the autograding service as often as you like, without losing any information. phase_6 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. need to, but we are careful never to type "make cleanallfiles" again. What is the Russian word for the color "teal"? What were the poems other than those by Donne in the Melford Hall manuscript? Solve a total of 6 phases to defuse the bomb. In this version of the lab, you build your own quiet bombs manually, and then hand them out to the students. Lo and behold, when we dump the contents of the memory address we get "%d", which tells us that the . Less than two and the bomb detonates. 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. Try this . Software engineer at Amazon. The problem requires that the return value of the func4 should also be zero. Thus I'm pretty confident that this will be the pass phrase for the first phase. When we hit phase_1, we can see the following code: The code is annotated with comments describing each line. From this, we can guess that to pass phase_1, we need to enter the correct string. Custom, notifying bombs are constrained to run on a specific set of Linux, hosts determined by the instructor. servers running. 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. Contribute to xmpf/cse351 development by creating an account on GitHub. In addition, most, phase variants are parameterized by randomly chosen constants that are, assigned when a particular bomb is constructed. The bomb is defused . At each iteration, we check to see that the current value is double the previous value. Binary Bomb Lab :: Phase 6. It's a great. There is a small grade penalty for explosions beyond 20. The report daemon finds the most recent, defusing string submitted by each student for each phase, and, validates these strings by applying them to a local copy of the, student's bomb. Video on steps to complete phase one of the lab.If y'all real, hit that subscribe button lmao This command lists all the current breakpoints as well as how many times each breakpoint has been hit on the current run. And when we execute it, it expects to receive certain inputs, otherwise it 'blows' up. I found the memory position for the beginning of phase_1 and placed a break point there. 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]. Make sure you update this. We can get the full assembly code using an object dump: objdump -d path/to/binary > temp.txt. (**Please feel free to fork or star if helpful!). Cannot retrieve contributors at this time.
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