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Article #266Re: /etc/passwd grungies
From: Doug Gwyn
Date: Sun, 09 Feb 1986 10:23
Date: Sun, 09 Feb 1986 10:23
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> BEWARE: In /etc/passwd blank or otherwise badly formatted lines can > cause *extremely* anomalous behaviour. This is an understatement. Any time a line of /etc/passwd is edited so that it contains the wrong number of fields, subsequent updating (e.g., by the "passwd" command) can produce one or more lines in /etc/passwd of the form ::0:0::: which has the interesting consequence that one can "log in" using a null username, not have to give a password, and end up as superuser. This problem was fixed in the /etc/passwd-reading library routines in UNIX System V, but not in 4.2BSD. I have seen this problem occur several times.
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Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Path: arc1-ca.pugleaf.net!utzoo!watmath!clyde!cbosgd!gatech!seismo!brl-smoke!gwyn From: gwyn@brl-smoke.ARPA (Doug Gwyn ) Newsgroups: net.bugs.usg,net.bugs.4bsd Subject: Re: /etc/passwd grungies Message-ID: <765@brl-smoke.ARPA> Date: Sun, 9-Feb-86 05:23:27 EST Article-I.D.: brl-smok.765 Posted: Sun Feb 9 05:23:27 1986 Date-Received: Tue, 11-Feb-86 06:34:57 EST References: <3039@mnetor.UUCP> Reply-To: gwyn@brl.ARPA Organization: /usr/local/lib/news/organization Lines: 16