Bugtraq: Re: vixie cron possible local root compromise

[Kris Kennaway <kris () OBSECURITY ORG>]

On Sun, Feb 11, 2001 at 12:38:02AM +0100, Flatline wrote:

> the login name is stored in a 20 byte buffer using the strcpy() function
> (which does no bounds checking). 'useradd' (the utility used to add users
> to the system)
> however allows usernames of over 20 characters (32 at most on my distribution).
>
> Therefore, running crontab as a user whose login name exceeds 20 characters
> crashes it.
I don't see any real-world scenarios where this would be exploitable -
usernames must be set by the administrator.  Even in the case of
e.g. a hostile NIS server, the NIS server can probably just add an
account with uid 0 and log in to the client with root privileges.

Kris

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