dmarcsyslogforwarder

README

DMARCSYSLOGFORWARDER

This program is used to read in dmarc reports from a dedicated IMAP mailbox and converts them to single entries and sends them in XML or JSON format via syslog to a remote server. This can be used to feed dmarc reports into your favourite SIEM.

As each dmarc report can contain multiple entries the report is split into single reports. The source ip from the report is also resolved via DNS.

This program does not work on windows as the golang syslog library is not compatible.

Syslog JSON Format

{
  "event_id": "",
  "event_category": "",
  "version": "1.0",
  "domain": "google.com",
  "date_begin": 1636416000,
  "date_end": 1636502399,
  "report_id": "",
  "org_name": "",
  "email": "noreply-dmarc-support@google.com",
  "extra_contact_info": "https://support.google.com/a/answer/2466580",
  "errors": null,
  "source_ip": "",
  "source_dns": [
    "domain1",
    "domain2",
    "domain3"
  ],
  "source_dns_string": "domain1, domain2, domain3",
  "count": 1,
  "envelope_to": "",
  "header_from": "",
  "envelope_from": "",
  "policy_published": {
    "domain": "",
    "adkim": "",
    "aspf": "",
    "p": "",
    "sp": "",
    "pct": "",
    "fo": ""
  },
  "policy_evaluated": {
    "disposition": "",
    "dkim": "",
    "spf": "",
    "reason": null
  },
  "result_spf": {
    "domain": "",
    "scope": "",
    "result": ""
  },
  "result_dkim": {
    "domain": "",
    "selector": "",
    "result": "",
    "human_result": ""
  }
}

Syslog XML Format

<syslog_entry>
  <!-- SIEM specif fields start (ommitted when empty) -->
  <event_id>FROM_CONFIG</event_id>
  <event_category>FROM_CONFIG</event_category>
  <!-- SIEM specif fields end -->
  <version></version>
  <domain>google.com</domain>
  <date_begin>1636416000</date_begin>
  <date_end>1636502399</date_end>
  <report_id></report_id>
  <org_name>google.com</org_name>
  <email>noreply-dmarc-support@google.com</email>
  <extra_contact_info>https://support.google.com/a/answer/2466580</extra_contact_info>
  <errors>
    <error></error>
    <error></error>
    <error></error>
  </errors>
  <source_ip></source_ip>
  <source_dns>
    <dns>domain1</dns>
    <dns>domain2</dns>
    <dns>domain3</dns>
  </source_dns>
  <source_dns_string>domain1, domain2, domain3</source_dns_string>
  <count></count>
  <envelope_to></envelope_to>
  <header_from></header_from>
  <envelope_from></envelope_from>
  <policy_published>
    <domain></domain>
    <adkim></adkim>
    <aspf></aspf>
    <p></p>
    <sp></sp>
    <pct></pct>
    <fo></fo>
  </policy_published>
  <policy_evaluated>
    <disposition></disposition>
    <dkim></dkim>
    <spf></spf>
    <reason>
      <type></type>
      <comment></comment>
    </reason>
    <reason>
      <type></type>
      <comment></comment>
    </reason>
  </policy_evaluated>
  <result_spf>
    <domain></domain>
    <scope></scope>
    <result></result>
  </result_spf>
  <result_dkim>
    <domain></domain>
    <selector></selector>
    <result></result>
    <human_result></human_result>
  </result_dkim>
</syslog_entry>

Config File

See the config.example.json for an example.

Fieldname	Description
format	can either be xml or json
fetchInterval	How often should the job fetch emails from the IMAP server and process them
syslogServer	The syslog server in the format ip:port
syslogProtocol	The syslog protocol. can be tcp, udp or "". On empty string the local unix socket is used
syslogTag	The syslog tag to add to all messages
dnsServer	a custom DNS server to use for queries. Uses the system default if left empty
dnsConnectTimeout	timeout when connecting to the DNS server
dnsTimeout	timeout when waiting on DNS answers
dnsCacheTimeout	how long should DNS answers be cached
batchSize	how many emails to fetch per login/logout run. As the IMAP server can simply close connections on timeout and the library can not handle reconnects the mails are fetched in multuple runs
eventID	Value that will be serialized into "EventID". May be needed by your SIEM to match the logs against a log type. This field does not appear in the XML if it's left empty.
eventCategory	Value that will be serialized into "EventCategory". May be needed by your SIEM to match the logs against a log type. This field does not appear in the XML if it's left empty.
imap.host	IMAP server in the format ip:port
imap.ssl	use SSL/TLS when connecting to server
imap.user	IMAP username
imap.pass	IMAP password
imap.folder	the IMAP folder the reports are in
imap.ignoreCert	Ignore invalid TLS certificates when connecting to the IMAP server
imap.timeout	Time to wait for imap commands to complete

Installation

adduser --system dmarc
mkdir /home/dmarc
chown -R dmarc:dmarc /home/dmarc
cd /home/dmarc
git clone https://github.com/FireFart/dmarcsyslogforwarder.git
cd dmarcsyslogforwarder
make
./install_service.sh