policyd-weight: Insecure temporary file creation

Background

policyd-weight is a Perl policy daemon for the Postfix MTA intended to eliminate forged envelope senders and HELOs.

Description

Chris Howells reported that policyd-weight creates and uses the “/tmp/.policyd-weight/” directory in an insecure manner.

Impact

A local attacker could exploit this vulnerability to delete arbitrary files or change the ownership to the “polw” user via symlink attacks.

Workaround

Set “$LOCKPATH = ‘/var/run/policyd-weight/’” manually in “/etc/policyd-weight.conf”.

Resolution

All policyd-weight users should upgrade to the latest version:

 # emerge --sync
 # emerge --ask --oneshot --verbose ">=mail-filter/policyd-weight-0.1.14.17"

This version changes the default path for sockets to “/var/run/policyd-weight”, which is only writable by a privileged user. Users need to restart policyd-weight immediately after the upgrade due to this change.