Thread: dll injection - 99% CPU Usage

  1. #1

    dll injection - 99% CPU Usage

    Hello again.

    First of all I would like to thank everyone who helped me in the previous post. I much appreciate it.

    As you know I am trying to develop an up to date program that bypasses a firewalls outbound protection. In order to prove that they aren't that good.

    Untill now we reverse engineerd backstealth ( This basically gave us the idea on how to go to work. This did not give us a working version, merely the method. After that we reverse engineerd the dll. And here is where the problems arised. So we decided to write our own dll.

    Now I have everything working. Except one thing I can not figure out. The dll injection works fine. I can even show message boxes from IE. But when the program wants to connect to the internet, IE suddenly uses 99% of my CPU and does NOT connect.

    I can almost do everything from that dll. I can call everything that is inside libraries loaded by the process as it seems. But that is no problem, a browser has loaded kernel32 and wininet. As said the process hangs when i execute internet related functions. The functions are called froma thread that belongs to IE, i checked that. The firewall is disabled.

    My question is when would such a problem occur? Is it my network perhaps? What would be the solution to this problem? Any tips and help are again very much appreciate it. I will mentione this board in the credits section when we publish it.

    Thanks in advance!

  2. #2
    The browser does not crash without the dll. Of course I tried the obvious things as attaching a debugger after IE locked up to find where the infinite loop is. But it does not seem to help and I do not know ASM. And the debug info generated for the injected dll doesn't seem to help as i am calling functions inside iexplore. I am sure it is locked up inside IE and not inside my DLL. I have no loops that would cause this behaviour in the dll code. I also tried to create a socket manually. Again no go.

    Any suggestions?

  3. #3
    Banned master5001's Avatar
    Join Date
    Aug 2001
    Visalia, CA, USA
    Hmmm it sounds like your dll is being opened more than once (probably more than a couple of hundred times). Try adding some logging in the DLL_PROCESS_ATTACH.

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