Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!usc!elroy.jpl.nasa.gov!ncar!midway!uwvax!uwslh!jiml From: jiml@uwslh.slh.wisc.edu (James E. Leinweber) Newsgroups: comp.unix.admin Subject: Re: Network-wide Mail Spool? Message-ID: <1990Nov14.070548.7618@uwslh.slh.wisc.edu> Date: 14 Nov 90 07:05:48 GMT References: Organization: Wisconsin State Laboratory of Hygiene Lines: 19 karl_kleinpaste@cis.ohio-state.edu writes: >Any reason why one couldn't place symlinks: ... [making /usr/spool/mail/someone a link to ~someone/.newmail] Mail is a traditional source of security holes in Unix, particularly in the presence of symbolic links. Be very careful around scenarios such as: rm .newmail; ln -s /etc/passwd .newmail echo "cracked::0:0:::/tmp" | mail $USER If the mail delivery agent runs set-uid root, and the directory containing the mail box is writeable by the user, and symbolic links are allowed in mailbox paths, it had better be a community of trusted users. Also, if the user mailbox lives under their home directory and you have disk quotas, you could run into denial of service security risks too. -- Jim Leinweber (608)262-0736 State Lab. of Hygiene/U. of Wisconsin - Madison jiml@sente.slh.wisc.edu uunet!uwvax!uwslh!jiml fax:(608)262-3257