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Questions tagged [struct]

A specific C language data-type construct which allow to declare a list of primitive types variables bound together in a single logical memory unit.

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25 votes
7 answers
7k views

How is a structure located within a disassembled program?

I took a basic 40-hr Reverse Engineering course a few summers ago. While teaching us to use IDAPro, the instructor demonstrated, rather quickly and without explaining much, how to label certain ...
Ken Bellows's user avatar
17 votes
3 answers
8k views

Parsing/Rescuing corrupted IDA database

I'm reversing an application with IDA. My VM crashed and left the IDA database in a corrupted unpacked state. The next time I tried to load it back, IDA gave me the following error message: The ...
Dominik Antal's user avatar
14 votes
2 answers
2k views

How do you set registers as structs within a function in IDA?

For example, in the following disassembly: .text:007C6834 014 mov eax, [esi+4] .text:007C6837 014 mov dword ptr [esi], offset ??_7CAvatar@@6B@ ; const CAvatar::...
Avery3R's user avatar
  • 1,258
12 votes
2 answers
16k views

How to find arrays of objects (entities, enemies) in a game I'm reversing with Cheat Engine?

I am reversing a game using Cheat Engine and OllyDBG, through this memory addresses within an FPS game are read and monitored, these addresses will contain the coordinates(xyz) of enemies. My ...
Daniel Filipe's user avatar
10 votes
3 answers
14k views

Converting a virtual table from .rdata into an IDA struct

Is there a way to convert a .rdata vtable entry to an IDA struct? An example of the vtable entry: And what the resulting struct should look like (but with all entries - this vtable specifically, ...
Jarryd Le Breton's user avatar
10 votes
1 answer
5k views

IDA Pro: use structs on parameters

I have a small function that is given a struct as parameters. The struct looks to something like this: struct my_struct { short a; unsigned int b; unsigned int c; }; Taking care of the ...
sqrtsben's user avatar
  • 340
8 votes
1 answer
4k views

radare2 ascii graph to image?

After analysing a function and pressing VV to go into graph mode, is it somehow possible to export/render the whole graph to an image? I have some huge main functions and it would be nice to have it ...
Paul G.'s user avatar
  • 183
8 votes
2 answers
3k views

How to deal with Static Memory Allocation while modifying an executable?

I'm not new to StackExchange, but I'm quite new to reverse engineering, so please be patient with me! :P At present I'm dealing with an executable that I would like to modify a little bit, for ...
Zarathos's user avatar
  • 185
7 votes
2 answers
2k views

Identifying possible structs in C/C++ disassembly

I'm currently working on taking apart a game (Soul Reaver: Legacy of Kain) and I often come across odd looking sections such as this in the decompiler *(_DWORD *)(a2 + 16) = a2 + 624; *(_DWORD *)(...
MicroTransactionsMatterToo's user avatar
7 votes
1 answer
3k views

Struct with negative offset in IDA possible

I have a structure which looks like this: RefString struct RefCount dd ? StrLen dd ? CString db... RefString ends When the code passes around a pointer, it doesn't point to the ...
Devolus's user avatar
  • 963
7 votes
1 answer
2k views

Read a struct from memory

I'm trying to load a struct defined in a program that i'm reading the memory of, so I can use it to define objects in my python debugger (in windows). What format do structs take in memory, and what ...
yarbelk's user avatar
  • 173
6 votes
2 answers
715 views

Reverse engineering Perl-compatible regular-expressions

I'm dealing with a piece of malware that does extensive use of PCRE (Perl-compatible regular expressions). Normally I would be able to read them, but it seems they're in some kind of binary format (...
Thomas Chopitea's user avatar
6 votes
1 answer
10k views

How to apply IDA structure to a pointer of a structure

I've encountered this function, which accepts a pointer to what I believe is a custom C struct. I came to this conclusion based on subsequent access to it. arg_0= dword ptr 4 ;struct passed in ...
vincentleest's user avatar
6 votes
2 answers
3k views

Creating a struct in IDA which contains a cString?

Normally I struct is a fixed size. Is it possible to define a structure which contains an element which has different sizes? To illustrate what I mean is this. The layout of the data in the file ...
Devolus's user avatar
  • 963
5 votes
2 answers
5k views

IDA PRO Structures Defining negative offset -4 -8 offset repair asm Hex-Rays

How do I fix structures in IDA PRO so they show up properly in Hex-Rays plugin (C decompiler). Similar question to: (But the solution doesn't work for me) Struct with negative offset in IDA possible ...
SSpoke's user avatar
  • 759
5 votes
1 answer
1k views

IDA: setting a register as a basepointer to struct

I read that question here (How do you set registers as structs within a function in IDA?) but this applies only to individual lines. Is it possible to set a register as a basepointer for a scope so ...
Devolus's user avatar
  • 963
4 votes
2 answers
894 views

Struct reconstruction in decompilers

I'm testing several decompilers about struct reconstruction, given the following C example: struct S { int x; int y; long z; long t; }; int foo(struct S s) { return s.x + s.y + s....
Ta Thanh Dinh's user avatar
4 votes
1 answer
7k views

In IDA how can I define a data address as a struct and array of datatype

As the title says im a bit lost on how to get something in the data section to be recognized as a struct or an array of structs or an array of strings etc. Cheers
Liam Mitchell's user avatar
4 votes
2 answers
3k views

Setting an IDA function pointer in a struct via script

The ordinary, manual way of redefining a struct member to become a function pointer would be to press on it, hit 'Y', and enter the proper declaration in the popup box. For example, for struct member ...
Sleeptime's user avatar
  • 147
3 votes
1 answer
376 views

What type of data structure is it?

I have the following data: .data:004305FC word_4305FC dw 1583h .data:004305FC .data:004305FE word_4305FE dw 35B6h ....
PSS's user avatar
  • 3,088
3 votes
2 answers
349 views

Problem with converting hex values to decimal

I'm reverse-engineering custom binary file format. I'm using 010 Editor to check this file. I found data structure to represent UTF-8 strings, which has header section of one or two bytes in length ...
Anthony J.'s user avatar
3 votes
1 answer
6k views

When defining a structure in IDA, can I define a field that is of another struct type?

I'm looking to define a structure in IDA like: struct StructA { int a; int b; } StructA; struct StructB { StructA a; int b; } StructB; Can I do this in IDA's structure definition ...
crush's user avatar
  • 233
3 votes
1 answer
2k views

IDA PRO Basics For Hex Rays How to fix address to struct which is dynamically calculated in if statement

I barely know any assembly and just started using IDA PRO a few months ago. I understand the code that Hex-Rays generates pretty well and I think I know why Hex-Ray's fails to create a struct of this ...
SSpoke's user avatar
  • 759
3 votes
1 answer
238 views

IDA Decompiler generates wrong output on array of structures!

There is a structure with size of 16-Bytes, and an array of it is defined. The disassembly code for navigation through the array is: MOV i, i,LSL#4 LDR R4, =arr_of_struct ADD i, i, R4 LDR ...
E.A's user avatar
  • 171
2 votes
1 answer
356 views

Identify two structs in IDA

When decompiling an exe file, I have defined two structs struct A and struct B that are of the same structure. They appeared under different contexts, thus I assumed that they were different structs. ...
WhatsUp's user avatar
  • 143
2 votes
2 answers
591 views

How to restore struct fields

I have an object named ComputeService::RPC that is being used as input in a function inside a binary file: __int64 __fastcall ComputeService::Rpc::GetClientProcessId(ComputeService::Rpc *this) pc *...
E235's user avatar
  • 583
2 votes
1 answer
2k views

What is __sighandler_t struct and purpose of SIGTRAP signal handler

I'm reversing an ELF x86 binary which apparently has anti-reversing/anti-debuging protections, and one of the first thing the ELF does is to call a sys_signal with a SIGTRAP value : .text:08048063 ...
Nark's user avatar
  • 283
2 votes
1 answer
420 views

How to reverse engineer structs in radare2?

Is there any way to indentify structs in radare2? when i tried to look them, they look like normal variables, i seen people using td and tl command but I don't know how to use them. If you know please ...
Mr. rc's user avatar
  • 45
2 votes
1 answer
146 views

What is the difference between uintX_n (used in IDA Pro) and unitX_t types?

During debugging a binary in IDA Pro, I've noticed types of the form 30 uint16_n 00000002 struct {uint16_t inner;} 42 uint32_n ...
Newbie's user avatar
  • 277
2 votes
2 answers
424 views

C++ structure containing a RTTI getter function?

I'm working on reversing a C++ application and I've come across a structure that contains a getter function that returns TypeDescriptor*, I've read some articles on RTTI and reversing C++ but can't ...
user3238415's user avatar
2 votes
1 answer
4k views

How can I define a struct in x64/x32Dbg?

See the image how there is ecx, ecx+4, ecx+8, ecx+24, etc... What if this is a struct and I want to define it... Can I do this in x64Dbg and if so, how? I do see a Struct tab in the hex dump area, but ...
the_endian's user avatar
  • 1,870
2 votes
2 answers
262 views

Locate member of a structure

In an assembly line, I have a call to gethostbyname(...). I have read that the return value of that function can be a pointer to a hostent structure (of course, it could be also a null pointer but for ...
user3097712's user avatar
  • 1,541
2 votes
1 answer
417 views

How do I reverse engineer structs that are put as parameters in a function

how do I go around figuring out where to reverse engineer a struct? As shown in the picture below, I have this function called "struct dynamic_array" which I want to reverse engineer and ...
Oliver Vedel Rasmussen's user avatar
2 votes
1 answer
906 views

How to properly label ALL structure members of C-style struct in IDA Pro

I've made a very trivial C program which throws a struct on the heap and then diassembled it. Surprisingly, IDA Pro actually identified the struct as soon as I added it by name using the Structures ...
the_endian's user avatar
  • 1,870
2 votes
2 answers
607 views

Need help unraveling the format (time, string, float/decimal, integer/float/decimal) in .dat file

The files (idx, dat) are from a plant/facility operational historian. The .dat file is supposed to have entries, each with identifier (tag name/id/key), value (decimal/float) for different times (...
tamersalama's user avatar
2 votes
2 answers
3k views

Initializing a struct in win32 assembly programming using MASM

I'm trying to create a demo program demonstrating struct(s) in MASM , I've written a code like this : struct1 struct first db ? second dw ? struct1 EndS .386 .model flat,stdcall option casemap:none ...
user3679015's user avatar
2 votes
1 answer
513 views

IDA PRO Struct Pointer Counter big number not starting from address offset 0, Lowers a bit slightly but not all the way to 0

I put the whole question in 2 images. From research, it seems I need to use Ctrl+R, but I don't think that's what I need since I couldn't lower the number a bit further in order to reach 0. I think ...
SSpoke's user avatar
  • 759
2 votes
0 answers
98 views

Is it no longer possible to re-order structures in IDA?

In older versions of IDA, you could right-click a struct in the structure view and change its position in the list, making it easier to separate "internal" vs "external" structs. ...
Drew McGowen's user avatar
2 votes
0 answers
55 views

PDF file have two trailers?

If I analyse multiple PDF files with a hex editor, I see that all of them have two trailers. That's possible if an object has changed or renewed (https://blog.idrsolutions.com/multiple-trailers-in-a-...
Moooz's user avatar
  • 21
1 vote
2 answers
785 views

Cross-referencing object fields

I'ld like to see which functions are operating with certain object's fields that I already processed, meaning I created the structure and assigned it to the correct places in the functions in IDA, ...
Dominik Antal's user avatar
1 vote
2 answers
3k views

Need Ideas to Reverse Engineer this HCC file format

January 17, 2015 update, We made some progress by converting the CSV to hcc file; however, MT5 is deleting the file. Attached is our code. Can someone help us? http://www.mediafire.com/download/...
Uncle Bob's user avatar
1 vote
1 answer
63 views

How are members of a Structure Type positioned on the stack?

Some of the structure types have members that are not stacked next to each other. Check out the structure type at 0x33E6 in bzip2_base (x86-64) here. There's an int at location offset 0, a char at 4 ...
Sav's user avatar
  • 15
1 vote
1 answer
110 views

Competitive Types

I have the following lines discovered in a piece of code (using IDA PRO) : ... ... push 44h pop edi push edi ; size_t xor esi, esi lea eax, [ebp+StartupInfo] push esi ; int ...
user3097712's user avatar
  • 1,541
1 vote
1 answer
2k views

IDA Pro: how to pass a function a pointer to a structure field

When a C++ subclass object is being passed to a function which accepts base class objects, the C++ compiler implementation is so the subclass object pointer gets shifted down to point to the ...
Igor Lebedev's user avatar
1 vote
1 answer
162 views

Define partial struct with IDA

I want to define struct in Ida , but I know only partial of this struct I only know that in arr[12] that int student_id , and I don't know the rest of struct. Ida recognize that struct as char * . How ...
func's user avatar
  • 43
1 vote
1 answer
330 views

How can I unpack this archive file?

I recently discovered a binary container file in a GameCube video game which I cannot unpack! I asked around, and I was told that it is an archive with this exact file structure: char Signature[8]; ...
Simon Aarons's user avatar
1 vote
1 answer
708 views

Where Ida Pro is using my defined structures

I'm have many functions that has a structure pointer as a function parameter (e.g. "VecInt *"). Ida knows that each function uses this type (because decompile window works fine). The same will happen ...
IdaNewUser's user avatar
1 vote
1 answer
558 views

Using members of a struct in Win32 (MASM)

Due to the following topic, Initializing a struct in win32 assembly programming using MASM I tried to correct my mistakes, So I tried the following code : .386 .model flat,stdcall option casemap:...
user3679015's user avatar
1 vote
0 answers
47 views

How can I create a radare2 type for a variable-length struct?

I'm trying to parse a binary file and it has a structure similar to this, struct foo { int64_t count_things; int64_t offset_to_thing[count]; int8_t bytes[]; int64_t other fields; } ...
Evan Carroll's user avatar
  • 1,789
1 vote
0 answers
281 views

Ghidra: undefined4 to bytearray

I am trying to reverse a c++ program and make the decompiler represent a byte-array in a single line. The c++ code contains the following line: BYTE fileArray[139] = {0x50, 0x51....} Ghidra ...
0x0000000000000000000's user avatar