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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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. ...
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Need help finding a windows struct

What I know about it: struct unknown_struct { struct _KAPC apc; struct _KEVENT event; char unknown[2056]; }; So first a kernel apc struct then a kernel event struct and the total size is ...
0 votes
2 answers
155 views

How to set a variable as "pointer to struct" in IDA in order to automatically replace offsets by field names?

In IDA, I have the following disassembly code (from an old 16-bit DOS application) : les bx, _Foo mov word ptr es:[bx+84h], 0FFFFh mov word ptr es:[bx+8Ch], 0FFFFh mov word ptr es:[bx+...
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Print CMarkupSTL object with GDB

CMarkupSTL is contain XML. How can I print that XML with GDB while I debug process? I run on Arm Linux
2 votes
1 answer
164 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 ...
2 votes
2 answers
152 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 *...
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-1 votes
2 answers
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Parse offset to PE struct

Im trying make my idb beautier. I want to parse the offset to PE structure. Here is some example: I want to parse (module + 60) to (module_base->e_lfanew) but when i change the type of module_base ...
1 vote
1 answer
102 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 ...
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1 answer
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troublesome stack frame setup

I have a function with the first few instructions defined as follows: sub rsp, 0x80 lea rbp, [rsp + 0x20] mov qword [rbp + 0x58], rsi mov qword [rbp + 0x50], rbx mov qword [rbp + 0x70], rcx mov ...
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0 votes
1 answer
183 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 ...
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How to replace a segment with a single structure consisting of the data in that segment - programmatically?

So I have something like this (I copied this from my other plugin functionality which simply creates a copy paste structure from the frame containing stack variables, while deleting them and then ...
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2 votes
1 answer
87 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 ...
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2 votes
2 answers
207 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 ...
1 vote
1 answer
55 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 ...
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0 votes
1 answer
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How is padding size calculated for members of structure types?

Looking at DWARFs of bzip2_base I see different offsets between members of a structure type although they are of the same type. Check _IO_FILE structure at the offset 0x9c here. All the way until the ...
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1 answer
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Generate dummy struct in IDA hexrays

I remember that hexrays has the option to generate a dummy struct from a pointer. That is if we access a pointer in offsets 0x36, 0x24 it will create a struct with members off24 , off36. In what ...
0 votes
1 answer
84 views

IDA: apply function parameter as struct pointer

In the following function foo .text:0000000000401110 foo proc near .text:0000000000401110 .text:0000000000401110 var_8 = qword ptr -8 .text:0000000000401110 .text:...
4 votes
2 answers
677 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....
2 votes
1 answer
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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 ...
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1 vote
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Process Memory Viewing Tool

I'm trying to remember a couple of tools that I used several years ago that allowed you to create structs and map certain regions of memory to those structures so you could view the correct data types ...
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2 votes
1 answer
657 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 ...
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1 vote
1 answer
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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 ...
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8 votes
1 answer
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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 ...
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3 votes
2 answers
301 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 ...
3 votes
1 answer
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 *)(...
0 votes
1 answer
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How can I export a struct in IDA Pro to a c-style struct?

I have a struct in IDA Pro that I want to export to a c-style struct. For example: 00000000 ICreateErrorInfo struc ; (sizeof=0x4, align=0x4, standard type) 00000000 ...
1 vote
1 answer
4k views

IDA Array of structs hiding strings

I have just started teaching myself IDA and I have had some trouble with an array of structs. I have found and defined a struct similar to this: (simplified) struct { char filename[50]; int field2; ...
6 votes
1 answer
9k 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 ...
1 vote
1 answer
585 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 ...
1 vote
1 answer
439 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:...
2 votes
2 answers
2k 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 ...
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 ...
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6 votes
2 answers
667 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 (...
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 ...
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2 votes
1 answer
436 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 ...
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2 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 ...
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3 votes
1 answer
5k 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 ...
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17 votes
3 answers
7k 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 ...
1 vote
2 answers
703 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, ...
5 votes
2 answers
4k 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 ...
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5 votes
1 answer
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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 ...
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9 votes
2 answers
12k 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, ...
3 votes
1 answer
6k 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
8 votes
1 answer
4k 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 ...
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5 votes
2 answers
2k 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 ...
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6 votes
1 answer
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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 ...
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6 votes
1 answer
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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 ...
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3 votes
1 answer
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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 ....
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12 votes
2 answers
15k 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 ...
13 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::...
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