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I am reversing a firmware update and found a empty password field in /etc/passwd

root::0:0:root:/:/bin/sh
otheruser:x:0:0:otheruser:/bin/false

Do I need a password to login as root?

I found out, that the x in the password field indicates that the hash is written in /etc/shadow, were a * indicates that the password is empty. The /etc/shadow is not included in the firmware update, so i don't know the content.

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    About the root user, it is normally not to have password in /etc/shadow because you want to use SUDO privileges instead of root user. Keep it disabled from remote logins and even local access. The only way you should access to root privileges is thru sudo.
    – Osakr
    Sep 25, 2018 at 11:32
  • If you want to permit login you would set the shell to /bin/false, rigth? The question is if the missing x means that a blanc password is used
    – trietend
    Sep 25, 2018 at 11:51
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    No, the shell /bin/false returns false immediately after login so you'll get logged out automatically. About the password, you're right about the blank password, currently your root user doesn't have any password assigned. You could set a ! to block the account for example
    – Osakr
    Sep 25, 2018 at 11:56
  • thanks, so maybe i can get a root-shell on the device :)
    – trietend
    Sep 25, 2018 at 12:16
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    However, this does not mean that SSH will allow root to log in without a password.
    – multithr3at3d
    Sep 25, 2018 at 21:10

1 Answer 1

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An empty password field means the root account can be accessed without any password.

An * or ! means the account don't have a password and no password will access the account. An x means the password is on /etc/shadow.

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