Windows Defender reports a Trojan for C project

[jorgenjo]

Hi!
Just installed Microsoft Visual Studio Community 2019, Version 16.6.0.
VisualStudio.16.Release/16.6.0+30114.105
Visual C++ 2019 00435-60000-00000-AA922
Windows 10 Pro, Version 1909, OS build 18363.836

Built a few test solutions/projects (C++ and C#). Seems to work OK.

However, when I try to build and then run a pure C program (should end up as a simple "Hello World!"), Windows Defender reports a Trojan:

Threat detected: Trojan:Win32/Fuerboos.C!cl
Alert level: Severe
Category: Trojan
Details: This program is dangerous and executes commands from an attacker.
Affected items: file: C:\Users\<user>\source\repos\helloworldc\Debug\helloworldc.exe

The source code in the single source.c file is only (no printf yet):

#include <stdio.h>

void main(void)
{

}

Build/run:

Create a new project
C++ Windows Console
Empty Project
Project name: helloworldc
Location: C:\Users\<user>\source\repos (default)
Place solution and project in the same directory: checked

Solution Explorer
Source Files
Right click: Add new item
C++ File (.cpp)
CHANGED NAME TO: source.c

BUILD
RUN: Local Windows Debugger
-> Windows Defender triggers, and error message from VS...

Seems to be 100% repeatable.

Continue reading...