Sebastian Krahmer discovered an issue in the way postfix handles mailboxes with
improper permissions and ownership.
It is possible for a user with permissions to create files in the mail spool
directory to create an insecure mailbox file for a known valid user. This
mailbox will retain the insecure permissions and ownership allowing anyone to
view the data.
The easiest example of this would be a local user with the ability to write to
the mail spool creates a file named 'root' which postfix will then delivery
root's mail into regardless of file permissions or ownership.
This issue affects Red Hat Enterprise Linux 3, 4, and 5.
This is public:
Created attachment 314316 [details]
Patch Suse used
Here is the patch Suse used. I'm not sure where it came form, or if it's right, but from looking at it, it should work.
The above patch did come from postfix upstream.
postfix-2.5.5-1.fc8 has been pushed to the Fedora 8 stable repository. If problems still persist, please make note of it in this bug report.
postfix-2.5.5-1.fc9 has been pushed to the Fedora 9 stable repository. If problems still persist, please make note of it in this bug report.
This issue has been addressed in following products:
Red Hat Enterprise Linux 5
Red Hat Enterprise Linux 4
Via RHSA-2011:0422 https://rhn.redhat.com/errata/RHSA-2011-0422.html
Red Hat would like to thank Sebastian Krahmer of the SuSE Security Team for reporting this issue.