Malwarebytes gives trojan warning for basic C# “Hello World!” program

Question

Basically, I just ran a scan of my computer with Malwarebytes (updated the definitions before running), and it said my \"helloworld\" program written in C# has a trojan.

Answer 1

The answer by Baldrick is likely correct, but there is also another possibility: There are viruses which search for random executables on the system and modify them by inserting their own code into them (this is, in fact, the original definition of "computer virus"). When you find that an executable which you know is trustworthy suddenly is reported as infected, you might be dealing with such a virus.

But unless your virus scanner reports other executables as the same virus, this is unlikely.

Answer 2

I just figured this out: change the "Guid" in AssemblyInfo.cs a little, then try again.

That worked for me.

Answer 3

The problem could be that the Backdoor.MSIL.PGen Trojan is typically called 'hello.exe'. The name of your executable is presumably 'hello.exe' or 'helloworld.exe'.

Just rename your project or change the output executable to something not containing 'hello', and it should stop detecting it.

This answer is somewhat speculative, but given the name of your project, and a history of over-aggressive detection of this malware (see here), it seems a reasonable stab.