Re: (newbie) Question about core linux security

From: Jim Richardson (warlock_at_eskimo.com)
Date: 02/11/04

  • Next message: Lew Pitcher: "Re: (newbie) Question about core linux security" 
    Date: Wed, 11 Feb 2004 01:41:34 -0800

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    On 10 Feb 2004 20:54:19 -0800,
     Sam Joharay <public_viewer@indiatimes.com> wrote:
    > Hi,
    >
    > A friend of mine pointed this out to me
    > (which I believe must be common knowledge
    > though I'm kinda surprised by it):
    >
    > Claim: If you have physical access to a linux
    > machine, you can gain root access. Furthermore
    > you can create a user with any name which will
    > have root access (thus leave a backdoor entry
    > for remote root access).
    >
    > How to: Reboot the PC. Hit Ctrl-X when the login
    > screen appears. You will get a command prompt
    > that says "boot:"
    > Type "linux 1"
    >
    > Once thus logged in, you have permissions to edit
    > all files. Edit /etc/passwd and add line:
    >
    > myuser::0:0:root:/root:/bin/bash
    >
    > Save file and exit (logout/reboot).
    > Now you have created a user with user name myuser
    > which has root privileges (try it).
    >
    >==============================================
    >
    > I want to know whether:
    >
    > a. this is a well known security flaw
    > b. if there is someway to prevent this.
    > c. is there anything that distinguishes a user thus
    > created from the root user (in terms of privileges)
    >
    >=============================================
    >
    > If the claim is true (I have tried it on the redhat
    > linux installation that I have) then IMHO, it means
    > that a linux machine is only as secure as the lock
    > that guards it.
    >
    > Please comment,
    > [Sam Jo]

    it's the same with any machine, if you have physical access, it's
    vulnerable. The OS is irrelevent. You can do the same thing with any
    version of MS-Windows.

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    -- 
Jim Richardson     http://www.eskimo.com/~warlock
If you can keep your head when all about you are losing theirs, you may have
an exciting future as a guillotine operator
  • Next message: Lew Pitcher: "Re: (newbie) Question about core linux security"

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