All Questions
9,514
questions
336
votes
16
answers
418k
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 ...
- 4,178
138
votes
2
answers
124k
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)...
- 18.9k
132
votes
14
answers
126k
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 ...
123
votes
2
answers
97k
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 to 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), ...
- 10.9k
101
votes
20
answers
138k
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 ...
- 4,056
92
votes
9
answers
303k
views
How do I reverse-engineer .so files found in Android APKs?
I know how to reverse-engineer normal Android APKs using tools like apktool and dex2jar, but I don't know how to work with obfuscation.
When I extract everything from APK, I get some Smali files (I ...
- 1,195
86
votes
3
answers
131k
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 ...
- 18.9k
76
votes
9
answers
85k
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'...
- 963
71
votes
7
answers
141k
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 ...
- 1,097
70
votes
2
answers
44k
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 ...
- 1,527
70
votes
3
answers
14k
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?
- 4,785
66
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 ...
- 1,475
63
votes
6
answers
32k
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 ?
- 18.9k
63
votes
7
answers
133k
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 ...
62
votes
7
answers
17k
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 ...
user1743
62
votes
8
answers
37k
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, ...
- 4,785
56
votes
7
answers
155k
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.
- 927
52
votes
5
answers
32k
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 ...
- 1,762
50
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: ...
user187
48
votes
4
answers
45k
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-...
- 2,435
47
votes
8
answers
33k
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 ...
- 2,435
45
votes
4
answers
23k
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, ...
- 563
43
votes
3
answers
28k
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 ...
- 3,208
42
votes
1
answer
93k
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 ...
- 429
41
votes
8
answers
81k
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?
- 907
40
votes
5
answers
127k
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 ...
- 7,542
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 ...
- 535
38
votes
9
answers
60k
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?
- 1,234
37
votes
5
answers
8k
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 ...
- 497
37
votes
5
answers
11k
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
...
- 3,059
37
votes
3
answers
12k
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) {
...
- 1,789
37
votes
3
answers
24k
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?
- 4,056
37
votes
3
answers
32k
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 ...
- 2,435
36
votes
8
answers
48k
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 ...
- 460
34
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 ...
- 927
34
votes
4
answers
16k
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 ...
- 1,639
33
votes
4
answers
33k
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 ...
- 4,056
33
votes
5
answers
29k
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 ...
- 443
32
votes
5
answers
56k
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 ...
- 1,326
32
votes
5
answers
5k
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 ...
- 421
32
votes
5
answers
11k
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 ...
- 2,475
32
votes
4
answers
12k
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 ...
- 9,178
32
votes
5
answers
24k
views
What is a good tools to reverse the effects of Minify on JavaScript?
Are there any scripts and/or online tools that can reverse the effects of minification?
I'm specifically looking to unminify a minified JavaScript file. Variable renaming is not a big issue, I want ...
- 816
32
votes
5
answers
43k
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 ...
- 18.9k
32
votes
1
answer
9k
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, ...
- 927
32
votes
2
answers
793
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'...
- 1,522
31
votes
1
answer
9k
views
How to reattach tabs in IDA?
I feel dumb for needing to ask, but I've been annoyed by this several times in the past and have yet to come across the answer.
Sometimes, when rearranging tabs in IDA Pro, I accidentally detach the ...
- 861
31
votes
9
answers
55k
views
Decompiling a 1990 DOS application
I have some crucial data written decades ago by an ancient 16bit DOS application. There are no docs, no source, and no information about the author. Just the 16 bit exe. I guess it's time for me to ...
- 599
30
votes
4
answers
43k
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 ...
- 475
30
votes
5
answers
55k
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 ...
- 433