Every reverse engineer, malware analyst or simply a researcher eventually collects a set of utility software that they use on a daily basis to analyze, unpack, and crack other software. This article will cover mine. It will be useful to anyone who has not yet collected their own toolset and is just starting to look into the subject. However, an experienced reverse engineer must also be curious about what other crackers are using.
In this short tutorial you'll learn to crack software with the help of ollydbg tool. No more Trial softwares, patch them yourself easily.ollydbg software = h.
- It is still relatively easy to crack almost any program in the world. This is mainly due to computer processes' ability to be completely manipulated by an assembly debugger. Using this, you can completely bypass the registration process by making it skip the application's key code verification process without using a valid key. This works because assembly allows you to speak directly to the.
- Now that you have a cracked the registration protection of this software, launch the software and type any serial number. This should work like charm! Conclusion: This reversing tutorial demonstrates basic reverse engineering concepts using OllyDbg on how to find.
- 2) Use breakpoint-analysis to step through the application and find a serial key from inside the debugger windows 3) Decipher the serial-key generation and create a key-generator to produce infinite product keys. As you can see here is a sample crack-me, “passwordapp.exe”. Upon clicking the application, it shows us to enter a password for.
- Ollydbg shows you a lot of data, but for now just notice the Assembly Code in the top left pane, and the Paused message in the lower right. When you load a program into Ollydbg, it starts in a 'Paused' state, with the Assembly Code window showing the first instruction. Running Putty in Ollydbg In Ollydbg, from the menu bar, click Debug, Run.
WARNING
This article is for information purposes only. Neither the editorial team nor the author assumes any responsibility for possible harm that may arise from the use of these materials.
Debuggers
Debugging an application is an essential part of studying it, so every reverse engineer needs a debugger at the ready. A modern debugger must support both Intel architectures (x64 and x86), so this is the first prerequisite.
We must also be able to debug kernel-mode code. You will need this every once in a while, especially if you want to look for zero-day vulnerabilities in OS kernels or reverse engineer malware in drivers. The main candidates are x64dbg and WinDbg. The first debugger works in user mode, while the second one can debug kernel-mode code.
x64dbg
This is a modern debugger with a good user interface, a worthy successor of OllyDbg. It supports both architectures (x64 and x86), and there are tons of useful plugins.
Granted, it has its downsides as there are a number of annoying bugs. But it is actively developed and supported. Since the debugger works in user mode, it is of course vulnerable to a wide range of anti-debugging techniques. This is, however, in part offset by the availability of many different debugger hiding plugins.
x64dbg has a built-in decompiler and imports reconstructor (both x64 and x86), supports code graph visualization and read/write/execute/access breakpoints. This debugger has enabled some hackers to break down the infamous Denuvo DRM system!
Why not OllyDbg
We haven’t included OllyDbg here because it is very outdated. It does not support the latest operating systems or x64. The app’s official website announced a x64 version and even reported some development progress, but the site itself has not been updated since 2014. OllyDbg is undoubtedly a milestone piece of software, but now it seems that its time has passed. There have also been fewer kernel mode debuggers since Syser Kernel Debugger, a successor to SoftICE, was abandoned.
WinDbg
WinDbg is one of the best kernel or driver debugging tools. This debugger is supported by Microsoft and included in the Windows Driver Kit (WDK). This is currently the most up-to-date and powerful kernel code debugger. It does not feature the user-friendly interface of x64dbg, but there are not many other options, as other debuggers don’t support kernel-mode code.
WinDbg supports remote debugging and can download debug symbols directly from Microsoft servers. The VirtualKD booster exists to speed up the WinDbg setup for debugging kernel-mode code in a VM. WinDbg is definitely not for beginners, but as you gain experience in reverse engineering and start testing various interesting options, you won’t be able to avoid it.
WinDbg enables you to view various system structures and easily disassemble NTAPI functions. Of course it can also be used to debug “regular” applications, but I prefer to unleash this powerful weapon only when it is really needed!
Disassemblers
Reverse engineering cannot exist without static code analysis tools. The current selection of disassemblers is not much better than that of debuggers, but there we still have some favorites. The IDA Pro disassembler is a de facto standard in antivirus labs. Next is the Radare2 reverse engineering framework (many reckon that Radare2 is on par with IDA).
IDA Disassembler
There are two versions of IDA, a paid Pro version and a free Starter version. The free version is limited to x86 and does not support plugins. The Pro version offers full functionality with a large number of supported processor architectures and plugin support.
IDA does have a built-in debugger with rather basic functionality, but its unconventional interface takes some time to get used to. IDA can also be augmented with the Hex-Rays addon, a decompiler of application source code into C code. This is very useful as it really speeds up program analysis.
Overall, IDA is a very powerful and polished tool with a long development history. Unfortunately, the Pro version costs about $500-1000 (depending on the license type) and they do not sell it to just anybody. So we have to make do with other options.
Radare2
Radare2 was initially conceived as a simple hex editor but grew into a full framework able to debug and disassemble all types of code including firmware, viruses and cracks.
Radare is a set of console tools including a debugger, disassembler, decompiler, hex editor, its own compiler, utility for comparing binary files and much more. There is also a GUI addon named Cutter that greatly improves the look and usability of Radare’s framework.
The framework supports a large number of processors and platforms, which enables it to compete with products like IDA Pro. Another big advantage of Radare is that it is an open source, free and community-driven project.
Additional utilities
We have covered the main tools, but reverse engineering also needs packer identifiers, network monitors, hex editors and many other utilities. Let’s have a closer look to the main ones.
Detect it Easy (DiE)
This is a great packer identifier with a large number of useful functions. For example, it allows you to view file section entropy, which facilitates visual identification of encryption.
It also has a resource viewer with a dump-to-disk feature. DiE enables you to easily access the import table and add plugins and scripts, configure signature scanning methods and view file headers. It fully supports PE and PE+.
There is only one problem with this program: a slow update cycle, although it has not been abandoned. In fact, a new version was released recently!
INFO
You can see examples of working with DiE in my previous articles: “Manual unpacking. Cracking a custom packer based on GlobeImposter 2.0 ransomware” and “The art of unpacking. Gutting the protection of the crafty GootKit banker”.
ExeInfoPE
This is another packer and protector detector. It has an unconventional interface that will not be to everybody’s taste. On the other hand, the program is frequently updated, offers numerous interesting functions and user-friendly tips for unpacking.
Overall, I would recommend it to beginners. ExeInfoPE has a number of automatic unpackers and will tell you which tool to use to crack a bolt-on protection system.
Of course, the program also offers the full set of standard features including a file header viewer, section viewer, hex viewer and even a number of built-in mini-utilities like TerminateProcess and more. ExeInfoPE also supports plugins.
HxD
Sometimes you may need to access HDD, memory or applications in binary mode. This is where hex editors come in handy, as exemplified by HxD. This program is free and frequently updated, supports popular formats, is good for searching and offers a user-friendly UI. There are other well-executed features, such as the ability to remotely erase (zerofill) files. There is also a portable version for easy storage on a flash drive.
HIEW
This hex editor has a long history, but it is still supported by its devs. It comes in free and paid versions (the latter is $20 without updates or $200 with lifelong updates). The Norton Commander-like interface might scare off a younger crowd, but it is easy to get used to. What is especially great about HIEW, is that you can work in “keyboard-only” mode by controlling all its functions via hotkeys.
Pestudio
A useful program for malware analysis. Prestudio automatically scans files samples with VirusTotal, offers an interesting view of the analyzed application’s import table functions, shows the application’s viral markers, used libraries and PE file header info. It also enables you to work with resources. In other words, this is a versatile antivirus tool for initial sample analysis.
PE-bear
Another interesting viewer/editor of PE and PE+ files comes with a packer/protector identifier and shows info on file headers, resources and sections. If you want to, you can view sections in hex mode and disassemble them into regular assembler mnemonics.
PE-bear has a user-friendly UI and file-comparing utility. The program’s only downside, despite its open source code, are its rare updates. So, if you find a bug, you can fix it yourself.
Fakenet-NG
This program emulates working with a network. When studying malware samples, you often need to see all their Internet activities: monitor DNS and HTTP queries, sniff traffic and identify IP addresses of the controlling servers (for example, if you are dealing with a ransomware bot). Your VM should of course be offline, but if the virus detects it, it won’t do all the things that it usually does.
Fakenet-NG is fully supported with frequent updates, so this utility can be used in the latest operating sytems.
ProcessExplorer
It would be hard to perform reverse engineering without programs from Sysinternals that monitor how applications access the filesystem and processes. ProcessExplorer shows all processes in a hierarchical tree view, so you can easily see their spawning order. You can also see which dynamic libraries they use, as well as their priority, digital signatures, processor usage and much more.
RegShot
A handy utility for monitoring registry changes. RegShot takes snapshots of the registry before and after you do some system or software changes.
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TCPView
A small program for monitoring an application’s network activity. You can see which ports it accesses (both local and remote), together with protocols, process identifiers and transmitted packet counters. Overall, this is one of the most useful tools for any hacker!
Resource Hacker
A popular program for editing resources, including manifests, icons, text dialog lines, cursor info and much more. You won’t need this functionality very often, but when you do, this is a suitable tool to have.
Summing up
We have covered the main utilities used for most reverse engineering tasks. I think this should be enough for a beginner. Your own list will grow as you progress.
Many reverse engineers end up writing their own targeted programs, plugins and scripts. You won’t be able to find tools for every task that will make your life easier. If you know similar software or want to share links to other useful tools, please do so in the comments!
Using API Monitor to crack copy protected software
This tutorial demonstrates how to use API Monitor to crack copy protected software.
Software cracking is the modification of software to remove or disable features which are considered undesirable by the person cracking the software, usually related to protection methods: copy protection, trial/demo version, serial number, hardware key, date checks, CD check or software annoyances like nag screens and adware – Wikipedia
For this tutorial we will be using Mirial Softphone which is a HD video conferencing application. This tutorial is for educational purposes only, so please do not use this to create or distribute a cracked copy of the software.
When you first install the application, it prompts you for a license file. After installing the license you have 30 days to evaluate the application. The expiration date is displayed on this screen; in our case it is March 15, 2011.
Trial applications usually store license information in either the registry or on the file system. Since this application prompted us for a license file, we know that it uses the file system. Start up the 32-bit version of API Monitor and enable API’s from the File Management category.
Select Hook Process from the File menu to start monitoring the application.
API Monitor will start monitoring and displaying API calls. The application should now display a message indicating that it is an evaluation version. Hit cancel to quit the application.
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Now that we have captured the API calls made by the application, we need to find the one that reads the license file. Scan through the calls in the API summary view until you find the right one.
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The application is reading from mirial.lic file. The name suggests that it might be a license file, so let’s open it up.
We’ve located the license file and it has the expiration date in it.
Modify the expiration date in the license file to 2012-03-15 and save the file. Now launch the application again. The application should now display an error indicating that the license is invalid. Hit cancel to quit the application.
Our next step is to start debugging the application right after it has read the license file. From Step 3, we know that the application uses CreateFileA to open the file and ReadFile to read the file. Setup a Breakpoint on CreateFileA and launch the application in API Monitor. The breakpoint will be hit multiple times; continue until you reach the one that opens the license file.
Switch back to API Monitor and enable a post-call breakpoint on the ReadFile API and disable the CreateFileA breakpoint. Now hit Continue to let the application run. API Monitor should now display the ReadFile breakpoint.
Now hit the Break button to have API Monitor generate a breakpoint in the application. You should now be able to attach to the application using a debugger.
Your debugger should now display disassembled instructions from the application
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If you look at the call stack, you’ll notice that the current frame is in apimonitor-drv-x86.sys. Use the debugger to step out until you reach code in the application.
The debugger is currently at a location right after the application has finished reading the license file and before it checks the validity of the license. We need to locate the code that performs this check and disable it.
The most common software crack is the modification of an application’s binary to cause or prevent a specific key branch in the program’s execution. This is accomplished by reverse engineering the compiled program code using a debugger such as SoftICE, OllyDbg, GDB, or MacsBug until the software cracker reaches the subroutine that contains the primary method of protecting the software (or by disassembling an executable file with a program such as IDA). The binary is then modified using the debugger or a hex editor in a manner that replaces a prior branching opcode with its complement or a NOP opcode so the key branch will either always execute a specific subroutine or skip over it. – Wikipedia
Stepping though some of the code, we come across this location which looks like a possible match to the code we’re looking for.
The value of register eax is 0, right after the function call. Let’s modify the value to 1 and continue running the application. The application displays a different error message this time; instead of an invalid license, the application is telling us that it is unable to locate the file.
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Now that we have pinpointed the location where the application checks for a valid license, all we need to do is to play around with the values and jmp instructions to find one that works. In this case, inverting the jump instruction from je to jne tells the application that it has a valid license file. Running the application with the modified code displays our new expiration date of March 15, 2012.