dil is the least significant byte of the rdi register. It is highly likely that the rax register is modified in there. To load the binary into x64dbg, below is the commandline you can use: Once, the binary is loaded, you will see six windows by default. The second JE jumps all the way down to the function. To move on, lets search for ‘rarkey’, these are my results (yours should be the same except for the addresses): This looks like the function is trying to find any of the allowed file formats. Register for our Application Security – State of the Nation report and fill in the survey! Okay, lets get back to our only useful find: If you put a breakpoint on there and resume (F9) the program, you notice that the breakpoint is actually getting hit within a second. You can see on the top right window that our password ‘pass123’ and original password ‘PASSWORD1’ is loaded onto the registers RCX and RAX for comparison. Then we patched this routine by removing the je instruction that was causing the application to execute in the non-registered state. The middle two windows, left one shows you the .text section of the assembly code, and right one shows the fastcalls in x64 assembly. I prefer to use the Mingw-x64 compiler, but some also use clang x64. This does not look like a coincidence. je at 00007FF70E2F80D2 is taken and mov al,1 is not executed. Let me quickly explain what these windows are: The top left window displays the disassembled code. We check what happens when je is not taken by changing the je with nop instructions (we could also invert je to jne). We have verified that the constant 369 in the instruction is used for the evaluation copy string. Then, press F7 to step inside the call function. So now the je has basically been erased and execution will continue at 00007FF70E2F80D4. It will walk you through the entire assembly code of the binary. We search for the instructions that modify the rax register. Memory addresses mentioned in this tutorial are likely to be different on your system. The evaluation copy string is not in the title bar any more and the “about” window also shows that the application is registered to “” (empty). To load the file in debugger either drag & drop it on the icon or attach the process to x64dbg (File→ Attach or Alt+A) The instruction at 00007FF70E2FAE07 that decides if the jne is taken, cmp byte ptr ds:[7FF7B92848E4],dil, compares the byte located at memory address 7FF7B92848E4 with the contents of the dil register. Press F9 again until the application runs. The only way that instruction could have been executed is by coming from address 00007FF7B91EAE20, which is also made clear by the grey dashed arrow on the left of the addresses. To search for strings, right click anywhere in the disassembled code -> Search for -> All Modules -> String References. To test out whether we have the right method, you can change the 2nd instruction its opcode from (JE) to JNE. And then you should see that RAX is changed to Zero. Now right click on the ‘Incorrect Password’ area and select Follow in Disassembler. And we see two jump statements after them. thanks. Search for the constant 873 in x64dbg: right click somewhere in the CPU window and goto Search for -> Current module -> Constant. Lets follow the code (step over, f8): As you can see, the jump (JE) wasn’t hit and we are going to execute the function located at 0x13F169968. More specifically, trace back which instructions preceded the instruction at 00007FF6A403AE4A, how did we get there? Set a break point at 00007FF70E2FAE0E and restart the application. The patch is fairly simple, if its JNZ it will always show the nag screen unless it actually should shows us the nag screen (the 1/10 times) screen. Once, you’ve reached this breakpoint, hit stepi (F7) till you reach the mov RCX, RAX or 0000000000401601 address. www.extremehacking.org We want to know what value is at memory location 7FF7B92848E4 and in dil when the application breaks at 00007FF70E2FAE07, because this value decides whether we come in the registration flow or in the ‘evaluation’ flow. Fastcalls are x64 calling conventions which is done between just 4 registers. WinRAR has a 32 and 64 bit installer, whereas the previous target (Internet Downloader Manager) only has a 32 bit installer. You might already have seen due the bytes between the last 2 addresses are minimal that they are really close to eachother: If tried figuring out what that function is used for, but I noticed it isn’t executed at all. We could trace back where dil is set or we can check whether the byte located at 7FF7B92848E4 is written to at some point. We are looking for jumps that will change the instruction flow to show another string in the title bar. Also, when you look through the method you will see strings like ‘reminder’ and you will see the link that is on the nag screen. To see what will happen when the jump is taken, we change jne to jmp, so it will unconditionally jump. We know a few strings when we executed the binary i.e. However, below are alternatives along with the download links which you can choose. Once, the binary is loaded, you will see six windows by default. That’s why I decided to reverse engineer it and write a tutorial upon it. Lets take ‘rarkey.key’. Reverse engineering tools in Windows are highly different from that of Linux, but on the assembly level, it would somewhat be the same. This is however a re-posting of my own blog from here. Now whenever you resume the program and get past the breakpoint a nag screen will appear! So, unlike GDB where we can supply the argument inside the GDB; in Windows, we will have to supply it during the loading of binary via the command line itself. ‘Incorrect password’, or ‘Correct password’ or ‘help’. The string evaluation copy appears to be in a string table with the constant 873 mapped to it. Now you are in the References tab of x64dbg. The value of eax is FFFFFFEE. We now need to modify the return value of 1 to 0 which is returned by the check_pass() function. As this is the only location where 369 is used it is highly likely that this instruction will load the evaluation copy string from the string table. ow if you are on 32bit you can use OllyDBG, if you are on 64bit you need to use another debugger. Change 369 to 368, which is 872 in hex. Hmm, that’s unexpected behavior as that would skip our patch. Once it is there, you can see our password pass123 loaded on to the RCX register from RAX register. Enter evaluation copy in the search box below. Today I’ll be showing you how to crack WinRAR. If nothing is found, make sure you are in the winrar.exe memory region by going to the Symbols tab and double clicking winrar.exe. ", Copyright 2015 Extreme Hacking | All Rights Reserved | Cyber Suraksha Abhiyan | Site Protected by Sadik Shaikh |, Advanced Ethical Hacking Institute in Pune, CEHv8 CHFIv8 ECSAv8 CAST ENSA CCNA CCNA SECURITY MCITP RHCE CHECKPOINT ASA FIREWALL VMWARE CLOUD ANDROID IPHONE NETWORKING HARDWARE TRAINING INSTITUTE IN PUNE, Center For Advanced Security Training in India, IT Security Training Information Security Traning Courses in Pune, Houston consulate one of worst offenders in Chinese espionage, say U.S. officials, Shocked I am. Click on the row with je and press space, enter nop and tick “keep size” and “fill with NOP’s”. It uses the jne (jump if not equal) condition, which means it will jump to crack_mex64.401636 if its is not equal to One. The string cannot be found, so most likely it is not stored as consecutive characters in the executable. String tables are used to save memory. Memory addresses mentioned in this tutorial are likely to be different on your system. We back trace from the end of the routine, which can be found by the ret instruction. Make sure that after you have saved the file you replace the original WinRAR.exe with your patched version. So, this is the point where our interesting function starts. Now the application is running inside the debugger and it will pause (break) at some address, this is the entry break point. Click OK once, and then click cancel to not further modify instructions. This type of breakpoint will break when a value is written to that memory address. Set a breakpoint at 00007FF7B91EAE20 by highlighting the row and pressing F2. April 23, 2018 This means the instruction you are at now, cmp eax, 13, will result in a value that is higher than 0. The only difference you would find would be the kernel level calls and the DLLs which would be of Windows rather than the libraries of Linux. Run x64dbg and open the WinRAR.exe executable in x64dbg by … Windows applications can store strings in a string table ‘resource’, so we use a tool to read the string tables of the executable which is called Resource hacker. In the previous blog here, we reverse engineered a simple binary containing plaintext password in Linux with the help of GNU Debugger (GDB). This site uses Akismet to reduce spam. These constants are used in the executable to load the string mapped to it. Once you have downloaded the required debugger, you can compile the source code which is uploaded on my Git repo here. The value of eax are the 32 least significant bits of the rax register (image), which can be seen on the top-right window in x64dbg. So the byte was written at 00007FF6F0E78FAB, with the instruction mov byte ptr ds:[7FF6F0F148E4],al. This is the same as disassemble main in GDB. There, the instruction cmp eax, 13 will compare the eax register with the value 13 (in hex), and set the ZF if eax <= 0x13. The EAX is a 32 bit register which is the last 32 bits of the RAX register. If you inspected the first JE you would notice that it jumps past the second JE. Now continue running the binary till it reaches the point where it checks the return value of the binary as to whether its Zero or One, which is at address 000000000040160C. Then watch what happens when we press F9 again. However for the curious cats, more information can be found here. Press F9 until the application runs. The registration routine can be found in many ways, but usually a good place to search is for certain strings. After exiting a routine call the return value is stored in rax. nop means no-op and does not execute anything. We found the registration routine by tracing back from the evaluation copy string. E.g. However, since we are only focusing on x64, we will have to use x64dbg which supports both x86 and x64 disassembly. Enter evaluation copy and click search. It could be some testing code or just there to brainfuck reversers but as long as the code won’t get executed we can leave it there and have no worries about it. Now since our passwords are different, it will be printing out ‘Incorrect password’. The string in the title bar has now changed to only xx days left to buy a license. at address 0000000000401594. JMP (jump) means that it will always take the jump, no matter what and that means we will never have to see the nag again :). Press ctrl+f to search for a string. Note. Remember, that our binary accepts an argument which is our password. al is the the least significant byte of the rax register, which is used to hold return values of routines (functions). I would recommend skipping this if you are A beginner. thanks, this is useful since i am studying about reverse engineering.
Conor Benn Girlfriend, Walmart Henry Rifle Price, Robert Deleo Salary, Michelle Witten Nurse, Rv Raffle 2020, How To Repot Watermelon Peperomia, Dafydd Ap Gruffydd, Baby Pitbulls For Sale, Bethany College Kansas Apparel, Television Segment For Short, Archangel Haniel Prayer For Love, Colin Larkin Gmp, Vicks Vaporub For Cellulite Before And After, Zeb Hogan Death, How Long Is The Timer In The Game Outburst, Jessica Ennis Net Worth, Metaphysical Name Generator, Fortnite Helicopter Controls, Nikki Bella House, Cod Burst Perk, Over Yonder Lyrics, Dbz Kai Ocean Dub, Cnco Members Height, The Kings Head Chichester, Dai Densetsu No Yuusha No Densetsu Volume 17 Summary, Daring Greatly Quote, Where Is The Neutron Located In The Atom, Flip Cup Variations, Biggest Soca Artist, Rylee Martell Video, ユナイテッド93 日本人 久下, Nissan Pulsar Bonnet, Example Of Broadsheet Newspaper, Gaelic Girls Names, Mpow Bluetooth Transmitter Airpods, Ballon Rouge Ballon Bleu Ballon Vert Joyeux Anniversaire, Nhl Trade Machine, Saluda County Sc Marriage License, Battlefield Of The Mind Chapters, What Does The Name Scarlett Mean In The Bible, Mame4droid Rom Set, Mimi Slinger Emmerdale Instagram, Miss Representation 123movies, Darling Nikki 700 Pounds, Easily Criticized Definition, Aldi Ready To Wok Noodles Syns, Erma Crossover Fanfiction, 300 Word Essay On Petty Theft, Achyutam Keshavam Rama Narayanam, Dbz Kai Ocean Dub, Bucyrus, Ohio Murders, What Does It Mean When A Girl Calls You Doll Face, Undercover En Ligne, Howell Binkley Cancer, Jermaine Agnan Pictures, Southwest Valley Constructors Douglas Az, Dentsville Sc History, Angular Material Mat Grid List,
