Bug#930361: exim4: Further on to CVE-2019-10149

[Brent Clark]

Package: exim4
Version: 4.89-2+deb9u4
Severity: important

Dear Maintainer,

This is just a FYI and I sure hope its nothing.

In light of CVE-2019-10149

What I did was build a vagrant instance with Exim 4.89-2+deb9u3 to
replicate the POC.

Please see https://pastebin.com/raw/EiLbpsH4 for successful
exploitation.

What was of interest to me, I upgraded to 4.89-2+deb9u4 and redid the POC.

Please see https://pastebin.com/raw/iqaJyHt2, but you will see is, the
file POC does not work, BUT mail still gets accepted.

Please see https://pastebin.com/raw/YLS7CBHY

I just want to double check is this is correct / acceptable.

Kind Regards
Brent Clark
P.s. Just a Q of food for thought, should not CHECK_RCPT_LOCAL_LOCALPARTS and / or
CHECK_RCPT_REMOTE_LOCALPARTS be updated in
/etc/exim4/conf.d/main/01_exim4-config_listmacrosdefs?

-- Package-specific info:
Exim version 4.89 #2 built 28-May-2019 20:13:55
Copyright (c) University of Cambridge, 1995 - 2017
(c) The Exim Maintainers and contributors in ACKNOWLEDGMENTS file, 2007 - 2017
Berkeley DB: Berkeley DB 5.3.28: (September  9, 2013)
Support for: crypteq iconv() IPv6 GnuTLS move_frozen_messages DKIM DNSSEC Event OCSP PRDR SOCKS TCP_Fast_Open
Lookups (built-in): lsearch wildlsearch nwildlsearch iplsearch cdb dbm dbmjz dbmnz dnsdb dsearch nis nis0 passwd
Authenticators: cram_md5 plaintext
Routers: accept dnslookup ipliteral manualroute queryprogram redirect
Transports: appendfile/maildir/mailstore autoreply lmtp pipe smtp
Fixed never_users: 0
Configure owner: 0:0
Size of off_t: 8
Configuration file is /var/lib/exim4/config.autogenerated
# /etc/exim4/update-exim4.conf.conf
#
# Edit this file and /etc/mailname by hand and execute update-exim4.conf
# yourself or use 'dpkg-reconfigure exim4-config'
#
# Please note that this is _not_ a dpkg-conffile and that automatic changes
# to this file might happen. The code handling this will honor your local
# changes, so this is usually fine, but will break local schemes that mess
# around with multiple versions of the file.
#
# update-exim4.conf uses this file to determine variable values to generate
# exim configuration macros for the configuration file.
#
# Most settings found in here do have corresponding questions in the
# Debconf configuration, but not all of them.
#
# This is a Debian specific file

dc_eximconfig_configtype='local'
dc_other_hostnames='REMOVED
dc_local_interfaces='127.0.0.1 ; ::1'
dc_readhost=''
dc_relay_domains='stephan.trial.co.za'
dc_minimaldns='false'
dc_relay_nets=''
dc_smarthost=''
CFILEMODE='644'
dc_use_split_config='false'
dc_hide_mailname=''
dc_mailname_in_oh='true'
dc_localdelivery='mail_spool'
mailname:stephan.trial.co.za
# /etc/default/exim4
EX4DEF_VERSION=''

# 'combined' -	 one daemon running queue and listening on SMTP port
# 'no'       -	 no daemon running the queue
# 'separate' -	 two separate daemons
# 'ppp'      -   only run queue with /etc/ppp/ip-up.d/exim4.
# 'nodaemon' - no daemon is started at all.
# 'queueonly' - only a queue running daemon is started, no SMTP listener.
# setting this to 'no' will also disable queueruns from /etc/ppp/ip-up.d/exim4
QUEUERUNNER='combined'
# how often should we run the queue
QUEUEINTERVAL='30m'
# options common to quez-runner and listening daemon
COMMONOPTIONS=''
# more options for the daemon/process running the queue (applies to the one
# started in /etc/ppp/ip-up.d/exim4, too.
QUEUERUNNEROPTIONS=''
# special flags given to exim directly after the -q. See exim(8)
QFLAGS=''
# Options for the SMTP listener daemon. By default, it is listening on
# port 25 only. To listen on more ports, it is recommended to use
# -oX 25:587:10025 -oP /run/exim4/exim.pid
SMTPLISTENEROPTIONS=''

-- System Information:
Debian Release: 9.9
  APT prefers stable-updates
  APT policy: (500, 'stable-updates'), (500, 'stable')
Architecture: amd64 (x86_64)

Kernel: Linux 4.9.0-9-amd64 (SMP w/2 CPU cores)
Locale: LANG=en_US.UTF-8, LC_CTYPE=en_US.UTF-8 (charmap=UTF-8), LANGUAGE=en_US.UTF-8 (charmap=UTF-8)
Shell: /bin/sh linked to /bin/dash
Init: systemd (via /run/systemd/system)

Versions of packages exim4 depends on:
ii  debconf [debconf-2.0]  1.5.61
ii  exim4-base             4.89-2+deb9u4
ii  exim4-daemon-light     4.89-2+deb9u4

exim4 recommends no packages.

exim4 suggests no packages.

-- debconf information:
  exim4/drec: