Subject: [secdir] Secdir review of draft-ietf-sieve-include-13

From: Radia Perlman <[email-masked]>
Date: Sun, 4 Dec 2011 21:22:31 -0800

Summary: No problems found with this document

Summary of document: This document specifies an extension to an existing
file format. That file format is defined in RFC5228 and specifies a format
for incoming mail filtering and sorting rules (e.g. if subject field
contains “Viagra” delete the message). This extension defines an ‘include’
command, which allows someone to hierarchically organize mail filtering
rules into separate files. The goal (among others) is so that there can be
some common filters that lots of users might want to use, users can
reference them with ‘include’ commands rather than copying their bodies
into their own filtering rules, and the common filters can then be updated
by a central authority and changes will automatically be reflected in each
user’s rules.
This extension only introduces one interesting new security concern, and it
is covered well in the security considerations. That concern is that a user
might be able to trick the mail sorting utility into opening files that the
user would not have permission to open. Depending on the OS, this might or
might not be easy for the mail sorting utility to avoid, but the security
considerations points out several variations, like making sure that file
names really are file names (and not something that could escape itself
into a shell script) and checking the access rules on the files to make
sure that there is no privilege elevation.

Radia