Description of problem: When an external SMTP session is established, and an address of "xxx" is specified on the MAIL FROM: line, sendmail blindly accepts this as valid. Note that "xxx@localhost" is rejected by sendmail. Version-Release number of selected component (if applicable): sendmail-8.13.1-2 How reproducible: Always Steps to Reproduce: 1. from a remote host, telnet host 25 2. EHLO foobar.redhat.com 3. MAIL FROM: <xxx> Actual results: 220 vaccine1.NoDak.edu ESMTP Sendmail 8.13.1/8.13.1; Wed, 26 Oct 2005 16:17:42 - 0500 EHLO nate.cc.ndsu.nodak.edu 250-vaccine1.NoDak.edu Hello nate.cc.ndsu.NoDak.edu [134.129.106.131], pleased to meet you 250-ENHANCEDSTATUSCODES 250-PIPELINING 250-8BITMIME 250-SIZE 26214400 250-DSN 250-AUTH GSSAPI DIGEST-MD5 CRAM-MD5 250-DELIVERBY 250 HELP MAIL FROM: root@localhost 553 5.5.4 root@localhost... Real domain name required for sender address MAIL FROM: root 250 2.1.0 root... Sender ok Expected results: 220 vaccine1.NoDak.edu ESMTP Sendmail 8.13.1/8.13.1; Wed, 26 Oct 2005 16:17:42 - 0500 EHLO nate.cc.ndsu.nodak.edu 250-vaccine1.NoDak.edu Hello nate.cc.ndsu.NoDak.edu [134.129.106.131], pleased to meet you 250-ENHANCEDSTATUSCODES 250-PIPELINING 250-8BITMIME 250-SIZE 26214400 250-DSN 250-AUTH GSSAPI DIGEST-MD5 CRAM-MD5 250-DELIVERBY 250 HELP MAIL FROM: root@localhost 553 5.5.4 root@localhost... Real domain name required for sender address MAIL FROM: root 553 5.5.4 root... Real domain name required for sender address Additional info: In /etc/mail/sendmail.cf, checks are made for various "localhost" addresses. "localhost.localdomain" is missing: # handle case of @localhost on address R<@> < $* @ localhost > $: < ? $&{client_name} > < $1 @ localhost > The following line wants adding to this: R<@> < $* @ localhost.localdomain > $: < ? $&{client_name} > < $1 @ localhost.localdomain > Note that localhost.localdomain still remains valid for local use, but not for remote SMTP use.
This request was evaluated by Red Hat Product Management for inclusion in a Red Hat Enterprise Linux maintenance release. Product Management has requested further review of this request by Red Hat Engineering, for potential inclusion in a Red Hat Enterprise Linux Update release for currently deployed products. This request is not yet committed for inclusion in an Update release.
I'm having a hard time understanding how this is a security vulnerability. What can be gained by sending mail as root?
An advisory has been issued which should help the problem described in this bug report. This report is therefore being closed with a resolution of ERRATA. For more information on the solution and/or where to find the updated files, please follow the link below. You may reopen this bug report if the solution does not work for you. http://rhn.redhat.com/errata/RHSA-2007-0252.html