Lowyat.NET: Latest topics by Mat Quasar

Which one do you need today?

Mat Quasar — Sat, 22 Feb 2025 22:30:32 +0800

Sensory Rest: Unplug or "digital detox", sit in silence.

Social Rest: Balance time alone and time with others, assess relationships that aren't supportive or meaningful.

Emotional Rest: Talk to a friend, journal, self-reflection and self-care.

Physical Rest:
Passive- napping, deep breathing, sitting.
Active- yoga, stretching, walking, massage, baths.

Mental Rest: Meditation, affirmations, scheduling breaks in workday.

Spiritual Rest: Prayer, scripture, journaling, time in nature.

Creative Rest: Poetry, play, dance, paint, write.

Photo taken inside an apartment's lift.

My first Win32 game prototype

Mat Quasar — Thu, 06 Feb 2025 15:49:33 +0800

Hi, this Win32 game prototype took me about 9 months from start to finish.

I started with console interface first, then finalized with GUI version.

It is written purely in FASM, using raw Win32 API.
Although it is in GUI, I use TextOutA function in GDI32.dll, which is just displaying text in GUI window, no graphics at the moment.

There is no collision detection yet, no scoring. What you can do with this program is:
1) Move the caret (gun) to the left or to the right
2) Shoot one bullet at one time
3) Watch the enemies moving around

For the enemies to move around, I use random number generator to predict the direction of movement.

I have included the source code here (EXE is not included as it is falsely detected as virus).
If you are interested to run the program, you can....
1) Download SHOOT.txt
2) Rename SHOOT.txt to SHOOT.asm
3) Download Flat Assembler for Windows
4) Run FASMW.EXE and open SHOOT.asm
5) Click Compile
6) Go to the File Explorer, and you'll see SHOOT.EXE along with SHOOT.asm.

Note: If you compile yourself, Windows Security won't detect this as virus. Of course, my code does nothing malicious.

But my game is still very crude, I might consider using GDI+ or SDL2 to develop my graphical version of 2D game.

It is challenging to read technical documentation

Mat Quasar — Wed, 04 Dec 2024 22:29:42 +0800

What do you understand in comprehending this section of technical documentation in Intel Software Developer's Manual?

Console App Development Service

Mat Quasar — Tue, 03 Dec 2024 15:15:13 +0800

I can help writing command-line program in Windows and Linux.

💎 It can be a simple database program using SQLite3.
💎 It can be a simple networking program.
💎 It can be a system or file utility.

The target architecture can be 32-bit or 64-bit.

My primary programming language is FASM, but I can also write C# console app.

A command-line program is a computer program that can work under terminal, for example, under Windows, it is CMD and PowerShell.

I uploaded some of my programs to this forum, you can try search for all topics in Codemaster and Linux & Open Source Software by FlierMate, FlierMate1, MatQuasar.

The difference in using timer in VB6 and Win32 API

Mat Quasar — Thu, 28 Nov 2024 18:21:42 +0800

For those who did Visual Basic 6, you must be familiar with using timer control in your application. Just drag and drop the Timer from the Toolbox:

Then start writing code, just set the Interval of the timer in design time or run time.
For this example, the timer is set during run time:

CODE

Private Sub Form_Load()
Timer0.Interval= 3000
Timer0.Enabled=True
End Sub

Public Sub Timer0_Timer()
Beep
End Sub

And you will get this Form1 application running: (It is best if set Timer control to Visible=False)

But how about using timer in other programming language? For example, in native Windows, C++ code can directly access the Win32 API to set and kill timer with callback.

Below are some example code taken from: https :// learn.microsoft.com/en-us/windows/win32/winmsg/using-timers

Creating a Timer:

CODE

// Set two timers.

SetTimer(hwnd, // handle to main window
IDT_TIMER1, // timer identifier
10000, // 10-second interval
(TIMERPROC) NULL); // no timer callback

SetTimer(hwnd, // handle to main window
IDT_TIMER2, // timer identifier
300000, // five-minute interval
(TIMERPROC) NULL); // no timer callback

The callback to the GUI window is through WM_TIMER message in the window procedure.
(We have to familiar ourselves with window class, window procedure, message loop, message queue while working with GUI window in Windows)

CODE

case WM_TIMER:

switch (wParam)
{
case IDT_TIMER1:
// process the 10-second timer

return 0;

case IDT_TIMER2:
// process the five-minute timer

return 0;
}

Or if initializing the timer with callback to your own TimerProc procedure, the parameters to pass are a little different:

CODE

// Set the timer.

SetTimer(hwnd, // handle to main window
IDT_TIMER3, // timer identifier
5000, // 5-second interval
(TIMERPROC) MyTimerProc); // timer callback

Destroying a Timer

CODE

// Destroy the timers.

KillTimer(hwnd, IDT_TIMER1);
KillTimer(hwnd, IDT_TIMER2);
KillTimer(hwnd, IDT_TIMER3);

This is the screenshot of the GUI window with timer I created in FASM:

(It will beep every 3 seconds, but I am not posting the code on here anyway)

WM_TIMER is a low-priority message among window messages like WM_PAINT.
Make sure messages like WM_PAINT does not block the message queue, or else WM_TIMER message cannot be read.

Do you have other example of programming language to share, as to how to use timer in your software project?

Avalonia Visual Basic 6

Mat Quasar — Wed, 20 Nov 2024 17:39:02 +0800

(This was first discovered by flashang)

https://github.com/BAndysc/AvaloniaVisualBasic6

QUOTE

A recreation of the classic Visual Basic 6 IDE and language in C# with Avalonia

For web version, go to https://bandysc.github.io/AvaloniaVisualBasic6/

For desktop version, download from: https://github.com/BAndysc/AvaloniaVisualBasic6/releases

If you build yourself from source, requires .NET 9.

Memory patch variable value of another program!

Mat Quasar — Tue, 19 Nov 2024 17:38:19 +0800

I posted this on somewhere before, but it was console version. The following is GUI (a message box) version.

So, this short article is going to demonstrate how to overwrite a variable value in memory of another program.
I have this gui.exe, which is popping up message box with default caption. But after I run hackmem.exe, the caption in the message box.... CHANGED! How this is even possible?

Well, with the help of such a dangerous API, WriteProcessMemory, this is possible, but the memory area to be written must be accessible.

Microsoft explains 'WriteProcessMemory' Win32 API function as:

QUOTE

Writes data to an area of memory in a specified process.

This is also called Process Injection, part of Offensive Security. I like to call it 'memory patch'.

So, let's see how it looks like:

Before:

After:

How to play:
1. Run gui.exe
2. Click Retry to repeat, or Cancel to quit, but don't click Cancel yet.
3. Run hackmem.exe
4. Now click Retry in gui.exe to see "new" message
5. Have fun!

In summary, the code flow of hackmem.exe is as below:

CODE

call [FindWindow]

call [GetWindowThreadProcessId]

call [OpenProcess]

call [WriteProcessMemory]

It will find a window by looking for its title called "gui" (the program to be hacked), then get process identifier from window handle, then open the process with PROCESS_ALL_ACCESS permission, and overwrite the beginning of data section of the EXE.

Let say my gui.exe gets loaded at 0x400000 (image base), and I put the data section (with variables) in the first section, the first section is going to be referenced at 0x401000, since memory alignment is 4KB (0x1000). If I put my data section after code section, then the memory area to overwrite is 0x402000, and so forth.

This is how WriteProcessMemory work, the function parameters:

CODE

BOOL WriteProcessMemory(

[in] HANDLE hProcess,

[in] LPVOID lpBaseAddress,

[in] LPCVOID lpBuffer,

[in] SIZE_T nSize,

[out] SIZE_T *lpNumberOfBytesWritten

);

I will need to put 0x401000 as 2nd parameter, or lpBaseAddress, with lpBuffer being the new data for the variable value of program running as hProcess.

I am not going to show the code, as you can find plenty of examples and tutorials online.

Shoot out to junyian, angch and flashang for keeping me in touch with IT.