Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Posting-Version: version B 2.10.1 6/24/83; site linus.UUCP Path: utzoo!linus!smk From: smk@linus.UUCP (Steven M. Kramer) Newsgroups: net.unix-wizards Subject: Re: Unix Security List Message-ID: <117@linus.UUCP> Date: Thu, 21-Jul-83 13:16:05 EDT Article-I.D.: linus.117 Posted: Thu Jul 21 13:16:05 1983 Date-Received: Thu, 21-Jul-83 20:50:23 EDT References: <3247@sri-arpa.UUCP> Organization: MITRE Corp., Bedford MA Lines: 22 OK -- there are many problems with UNIX. We have 4.1 and have had security problems in the past. Let's start with mail. Rather than give the penetration scenarios, this list the fixes to mailing: in /usr/src/cmd/mail.c: put a setuid(getuid()) before the call to delivermail. /usr/src/cmd/delivermail/deliver.c: put a if(access(filename,2)!=0)return(CANTCREATE); before the fopen(filename,"a") /usr/src/cmd/mail.c: make MAILMODE ~0600 /usr/src/cmd/ucbmail/lex.c: after the check for 'No mail for %s' do a stat and see if the file is empty. If so, also print 'No mail for %s' and return(-1); /usr/lib/Mail.rc : make sure 'set keep' is in (to truncate rather than delete null mail files from /usr/spool/mail. Note this is because in 4.1 close(creat) calls itrunc() in the OS and doesn't touch the directory, which bring us to the next and final step:) /usr/spool/mail: make mode 711 Now, mail is secure for your machine. Next step is uucp, but I haven't done that fully yet. -- --steve kramer {allegra,genrad,ihnp4,utzoo,philabs,uw-beaver}!linus!smk (UUCP) linus!smk@mitre-bedford (ARPA)