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323 votes
16 answers
396k views

Is there any disassembler to rival IDA Pro?

Is there any disassembler (not only a live debugger) second to IDA in capabilities? IDA is wonderful, and somewhat amazing in how robust and useful it is for reversing. However, it is quite expensive ...
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  • 4,028
125 votes
14 answers
124k views

Where can I, as an individual, get malware samples to analyze?

It seems that a popular use of software reverse engineering skills is to reverse malicious code in an effort to build better protection for users. The bottleneck here for people aspiring to break ...
119 votes
2 answers
104k views

What is PLT/GOT?

From time to time, when disassembling x86 binaries, I stumble on reference to PLT and GOT, especially when calling procedures from a dynamic library. For example, when running a program in gdb: (gdb)...
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  • 18k
116 votes
1 answer
89k views

How to handle stripped binaries with GDB? No source, no symbols and GDB only shows addresses?

I have GDB but the binary I want reverse engineer dynamically has no symbols, that is when I run the file utility it shows me stripped: ELF 64-bit LSB executable, x86-64, version 1 (SYSV), ...
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  • 10.5k
95 votes
20 answers
126k views

Decent GUI for GDB

Learning the GDB commands is on my bucket-list, but in the meantime is there a graphical debugger for *nix platforms that accepts Windbg commands, and has similar functionality? For example, the ...
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  • 3,836
83 votes
9 answers
262k views

How do I reverse engineer .so files found in android APKs?

I know how to reverse engineer normal android APKs using tools like APK-tool anddex2jar but i don't know how to work with obfuscation. Can anyone help or atleast provide some pointers? I know this ...
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  • 1,105
81 votes
3 answers
121k views

How are the segment registers (fs, gs, cs, ss, ds, es) used in Linux?

I try to understand the process of memory segmentation for the i386 and amd64 architectures on Linux. It seems that this is heavily related to the segment registers %fs, %gs, %cs, %ss, %ds, %es. Can ...
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  • 18k
72 votes
9 answers
80k views

Analyzing highly obfuscated JavaScript

I was recently analyzing a web page that contained some highly obfuscated JavaScript - it's clear that the author had went through quite a bit of effort to make it as hard to understand as possible. I'...
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66 votes
2 answers
42k views

What is DLL Injection and how is it used for reversing?

I was reading a discussion about dumping a processes part of a process's memory and someone suggested using DLL injection to do this. I'll be honest in that I don't really understand. How does DLL ...
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  • 1,387
66 votes
3 answers
12k views

What is the purpose of 'mov edi, edi'?

I see this instruction in the beginning of several Windows programs. It's copying a register to itself, so basically, this acts as a nop. What's the purpose of this instruction?
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  • 4,465
64 votes
7 answers
128k views

What are the possibilities for reverse engineering an IPA file to its source?

I browsed a lot, but can't find any resources for reverse engineering an IPA file (iPhone application). Is there any method to reverse engineer an IPA file to its source? I've tried to rename it to ...
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64 votes
4 answers
5k views

How can I analyze a potentially harmful binary safely?

I've recently managed to isolate and archive a few files that managed to wreak havoc on one of my client's systems. So I was wondering what software and techniques make the best sandbox for isolating ...
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  • 1,425
62 votes
6 answers
30k views

Where to find (free) training in reverse engineering? [closed]

Can someone give a list of websites with good (and free) reverse engineering training exercises ?
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  • 18k
59 votes
7 answers
125k views

What is a good Java decompiler and deobfuscator?

I am using JD-GUI to decompile Java JAR files, but the problem is that it leaves many errors, such as duplicate variables which I have to fix myself and check to see if the program still works (if I ...
58 votes
7 answers
16k views

Visualizing ELF binaries

I recently saw an older talk by Sergey Bratus and Greg Conti by the name of Voyage of the Reverser: A Visual Study of Binary Species. Are there any opensource/free tools that one could use to see ...
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56 votes
8 answers
33k views

how can I diff two x86 binaries at assembly code level?

I'm looking for a tool like Beyond Compare, meld, kdiff, etc. which can be used to compare two disassembled binaries. I know that there's binary (hex) comparison, which shows difference by hex values, ...
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  • 4,465
52 votes
7 answers
139k views

How to know in which language/technology program (.exe) is written?

How to understand if exe/dll is written in C++/.Net/Java or in any other language. I tried to use Dependency walker but not able to get required information.
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51 votes
5 answers
30k views

Bypassing copy protection in microcontrollers using glitching

The ATmega microcontrollers generally have two lock bits, LB1 and LB2. One prevents further programming, and the other prevents the flash being read back. If both are set, the chip needs to be erased ...
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  • 1,672
49 votes
12 answers
5k views

Where to find information about a file format?

Let's say I found 'some' file (might be an executable, might be data, or something else) and want to run or read it. I open this file in a text editor, but the format isn't readable. Examples include: ...
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47 votes
4 answers
43k views

Is reverse engineering and using parts of a closed source application legal?

Is it legal to reverse engineer certain features of a closed source application and then integrate those features into a closed or open source application that may be either a commercial or non-...
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  • 2,275
45 votes
8 answers
32k views

How do I add functionality to an existing binary executable?

I want to add some functionality to an existing binary file. The binary file was created using gcc. Do I need to decompile the binary first, even though I sufficiently understand the functioning of ...
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  • 2,275
42 votes
4 answers
22k views

convert this x86 ASM to C?

How could this 32-bit x86 assembly be written in C? loc_536FB0: mov cl, [eax] cmp cl, ' ' jb short loc_536FBC cmp cl, ',' jnz short loc_536FBF loc_536FBC: mov byte ptr [eax], ' ' loc_536FBF mov cl, ...
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42 votes
1 answer
92k views

Decompiling iPhone App

I've been searching this site and more, but I haven't had much luck. I want to decompile an app to see how part of it works, and I've tried multiple programs. I've tried Hopper, IDA, and some other ...
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41 votes
3 answers
26k views

Unpacking binaries in a generic way

I find that more and more often binaries are being packed with exe protectors such as upx, aspack etc. I tried to follow a few tutorials on how to unpack them but the examples are often quite easy ...
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  • 2,908
40 votes
8 answers
78k views

Is there any way to decompile a .NET assembly or program?

Are there any tools available to take an already compiled .dll or .exe file that you know was compiled from C# or Visual Basic and obtain the original source code from it?
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  • 877
39 votes
8 answers
7k views

What are the targets of professional reverse software engineering?

At the professional level, for what purpose is reverse software engineering used? What software is targeted and why? For reasonably complex compiled code that's doing something novel, making ...
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37 votes
5 answers
103k views

How do you reverse engineer an EXE "compiled" with PyInstaller

Having recently watched/read a presentation given by Dave Kennedy at DEF CON 20 [PDF], I'd like to know how to decompile a Python script compiled with PyInstaller. In his presentation, he is creating ...
user avatar
  • 7,322
37 votes
9 answers
58k views

How does one reverse engineer a SWF file?

What tools and techniques exist to either decompile or analyze the bytecode in a SWF file? What resources are available to the reverse engineer to learn more about SWF internals?
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  • 1,194
36 votes
5 answers
7k views

What is the reason for this method to call itself?

While reversing a 32bit Mach-O binary with Hopper, I noticed this peculiar method. The instruction on 0x0000e506 seems to be calling an address right below the instruction. What would be the reason ...
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35 votes
3 answers
11k views

How can I reverse optimized integer division/modulo by constant operations?

When compiling a division or modulo by a constant, my compiler (LLVM GCC) generates a series of instructions that I don't understand. When I compile the following minimal examples: int mod7(int x) { ...
user avatar
  • 1,729
35 votes
3 answers
31k views

How do I figure out what is burned on an Arduino ROM?

I have an Arduino Uno Rev3. I would like to extract and find out what code is burned on the ROM of the micro-controller board. How do I extract the code from the board? How do I figure out the ...
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  • 2,275
35 votes
8 answers
43k views

Reverse engineering T-Disk barcodes for Tassimo coffee makers

In hope this is appropriate I have a Bosch Tassimo TAS2002EE coffee maker that uses T-Disks. Those contain coffee/milk/something else, and a barcode that is supposed to tell the machine how to deal ...
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  • 450
34 votes
5 answers
10k views

How can I analyse an executable with no read permission?

I have a binary on a Linux (Kernel 2.6) which I can execute, but can't read (chmod 0711). Therefore no static analysis is possible. user1: $ ls -l bin -r-s--x--- user2 user1 bin user1: $ file bin ...
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  • 2,849
33 votes
7 answers
11k views

What hints in machine code can point me to the compiler which was used to generate it?

When I am looking at the machine code of an application, are there hints and patterns I can discern from the generated machine code which would indicate which compiler (and possibly version) was used ...
user avatar
  • 877
33 votes
5 answers
27k views

Open source GUI tool for decomposing a PDF

I've been looking for an open-source GUI tool to extract PDF's in an automated way on Windows systems. I've used Didier Steven's tools with great interest for a while, but cannot make sense of how to ...
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  • 443
32 votes
3 answers
21k views

What is a FLIRT signature?

I've seen this referenced in a couple of other questions on this site. But what's a FLIRT signature in IDA Pro? And when would I create my own for use?
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  • 3,836
31 votes
4 answers
14k views

How to reverse engineer a Windows 10 UWP app?

I wanted to see what Microsoft are doing when you click "Restart now" button in their Settings -> Update window on Windows 10: Somehow the results are not the same what is available via ...
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  • 1,275
31 votes
5 answers
4k views

Why is disassembly not an exact science?

Newbie here. From Wikipedia Disassembly is not an exact science: on CISC platforms with variable-width instructions, or in the presence of self-modifying code, it is possible for a single ...
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  • 411
31 votes
4 answers
37k views

What is the meaning of movabs in gas/x86 AT&T syntax?

I just found a strange instruction by assembling (with gas) and disassembling (with objdump) on a amd64 architecture. The original amd64 assembly code is: mov 0x89abcdef, %al And, after gas ...
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  • 18k
31 votes
2 answers
762 views

What is the current state of the art for platform modeling?

When we're doing reverse engineering, we have a few levels of models. One of them is the instruction semantics model, which tells us what every native instruction does to modify instruction state. We'...
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  • 1,432
30 votes
5 answers
53k views

How do I acquire SoftICE?

I have seen mentions of SoftICE on various questions throughout this site. However, the Wikipedia article on SoftICE implies that the tool is abandoned. Searching google, I see many links claiming to ...
user avatar
  • 1,236
30 votes
5 answers
10k views

Why there are not any disassemblers that can generate re-assemblable asm code?

I am struggling on this problem for around three months: How to use disassemblers (IDA Pro and others...) to generate re-assemblable asm code and assemble it back My experience is that: There is NO ...
user avatar
30 votes
4 answers
32k views

How do I identify and use JTAG?

I'm a software guy through and through. But periodically when I'm taking apart hardware I know to look for JTAG ports and RS232 ports. So far I've always been lucky and have been able to solder on ...
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  • 3,836
29 votes
5 answers
51k views

What is the linux equivalent to OllyDbg and Ida Pro?

What is the Linux equivalent to OllyDbg and IDA Pro ? Or if there are multiple tools that do the various functions that OllyDbg and IDA Pro do, where can I find these tools? I'd like to start ...
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  • 423
29 votes
2 answers
10k views

Why are machine code decompilers less capable than for example those for the CLR and JVM?

Java and .NET decompilers can (usually) produce an almost perfect source code, often very close to the original. Why can't the same be done for the native code? I tried a few but they either don't ...
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  • 7,814
29 votes
1 answer
42k views

What does mov qword ptr ds:[rax+18], r8 mean?

mov qword ptr ds:[rax+18], r8 In the above code, where are we copying the value of r8 register into? I know that ds means data segment which is a segment in memory, but what does exactly [rax+18] ...
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  • 589
29 votes
6 answers
13k views

Decompiling Android application

The Android java code is compiled into Dalvik byte code, which is quite readable. I wonder, is it possible in theory and in practice to write a decompilation software for Dalvik byte code?
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  • 4,465
29 votes
1 answer
8k views

What kinds of steps can I take to make my C++ application harder to reverse engineer?

If I am building a C++ application and I want to make it more difficult to reverse engineer, what steps can I take to do this? Does the choice of compiler affect this? What about compiler flags, ...
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  • 877
28 votes
4 answers
39k views

Cross debugging for ARM / MIPS ELF with QEMU/toolchain

as i'm new about cross-debugging and cross-compilation i need some help because i feel so confused. I have a MIPS elf file, [myelf][1] .You can see bellow the output of file myelf: myelf: ELF 32-bit ...
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28 votes
1 answer
92k views

Reversing ELF 64-bit LSB executable, x86-64 ,gdb

I'm a newbie and just got into RE. I got a ELF 64-bit LSB executable, x86-64. I'm trying to reverse it. First I tried to set a break point on line 1 using gdb ./filename break 1 The gdb says No ...
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  • 433

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