Executing data by a program

[Gregor]

Hello

I'm trying to program a self updating program that would just expand in place. I plan to use modules of code that will consist of instructions or resorces. Modules will be able to point to resource modules (it probably wont work because of compiler optimizations, but I'll worry 'bout that later), etc...but thats another story!

Bottom line, I need to know how to run code from memory.



I have truble describing what I want to do, but the following seems to make sense.


Let's say that I have a virus, a trojan. It waits for some data and than it executes it - load to memory and exec. I would like to know if you can execute .exe programs this way...some general info.


I'm wondering if the following would work (verlflow errors atm)

void execute(char * parameters)
{
	unsigned i,size;
	//Open a file
	ifstream file( parameters , ifstream::in|ifstream::binary);
	//Load to memory
	char* tmp,* mem = (char*)malloc(16777216);//Allocate 16 MB of memory
	size=16777216;
	for(i=0; file.good();  i++){
		if(i<size)
			file.read(mem+i, 1);
		else//Try to resize the array
		{
			tmp=mem;
			if(!realloc(mem, size+16777216)){//On fail
				free(tmp);
				cout<<"FAILED! Error loading into memory"<<endl;
				file.close();
				return;
			}
			size+=16777216;
		}//Resized
	}
	tmp=mem;
	if(!realloc(mem, i-1)){//On fail
		free(tmp);
		cout<<"FAILED! Error loading into memory"<<endl;
		file.close();
		return;
	}
	function f=(function)mem;
	f();
	file.close();
	free(mem);
	cout<<"Executed."<<endl;
};

Thanks!

[jsmith]

Not sure anyone is going to help write a virus...

[Gregor]

Mr. Obvious strikes again!:P
Yeah I know how it looks, and sadly its mostly used for that purposes - that's why I used a virus to describe what I need to do.

Please dont make me go postin' on chans:S Sick stuff there!

Update: Changed the description a bit

[jsmith]

So what are you trying to do then?

Newer CPUs have an option to disable execution from writable memory pages.

[writetonsharma]

i dont understand what you are talking.. what data you want to execute??

you can use a couple of things to have a trojan or virus like behavior..
1. key loggers, trapping keys and sending it on network..
2. dll injections which let you control any process on windows.. you can even inject your dll into windows explorer and explorer or any process will get mad..
install services with a different name and they wont come in the task manager.

and the good thing is you don't have to implement them.. microsoft has done all the hard work. ;)

[Gregor]

After some more research I came to see that this is not what I've been looking for, I cant do what I want to, not on OS level anyway.


So I ask how would you build a self updating program that could be loaded in parts - should I just use loads of dlls and one small exe? Is there a way I can store a dll in the exe itself?


Save me the research, i'd be much apprechiated

[writetonsharma]

you can create a self-extracting binary then. the same binary will run and as well as extract the dll from it when required. load it in the memory.

you can find tutorials or even full code on how to create self-extracting binary on

codeproject.com.

but your problem looks quite vague..i think you are not clear what you want to do??

[Gregor]

Yes, totaly. I'm looking into stuff to decide what my next project should be...posts like this actualy help me a great deal!

Thanks:D