Re: Writing a SECURE daemon

From: Volker Birk (bumens_at_dingens.org)
Date: 11/07/03

  • Next message: Volker Birk: "Re: Searching for security article." 
    Date: Fri, 7 Nov 2003 09:34:42 +0100

    Mario L. Mueller <mario@goopers.com> wrote:
    > What do you mean by "split" the code?

    I.e. make two services which are communicating via IPC.

    > A separate
    > thread?

    A thread will not be enough because it runs with the UID of the
    calling thread. You need another process.

    > In my current code, I've setuid and setgid within the same executable
    > to a special user "mydaemon.mydaemon", since this user/group has
    > restricted access on the server. And I'm wondering if this is enough
    > to achieve what you're suggesting.

    This is better than nothing. But think about using two processes.
    Also using inetd could be a good choice. You then can run everything
    without UID 0.

    > Maybe I'm overlooking something, but is it safe to assume that only a
    > hacker who has access to the source code would be able to take
    > advantage of these unchecked buffers?

    No, the object code is already enough to examine such holes.

    > Or in other words, are there
    > ways for hackers to find unchecked buffers to exploit without
    > referencing the source code? (Disregarding psychic hackers) :-)

    Disassemblers and Debuggers exist.

    VB. 

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