mgeeky-Penetration-Testing-.../phishing/decode-spam-headers
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img moved decode-spam-headers to a separate folder. 2021-10-28 19:08:37 +02:00
decode-spam-headers.py updated decode-spam-headers.py 2021-10-28 19:45:41 +02:00
README.md update 2021-10-28 19:13:45 +02:00

decode-spam-headers.py

This tool accepts on input an *.EML or *.txt file with all the SMTP headers. It will then extract a subset of interesting headers and using 79+ tests will attempt to decode them as much as possible.

This script also extracts all IPv4 addresses and domain names and performs full DNS resolution of them.

Resulting output will contain useful information on why this e-mail might have been blocked.

Example screenshots

  • Chain of MTA servers (nicely parsed Received headers):

1.png

  • Various headers decoded as much as possible, according to publicly available documentation (here Office365 ForeFront Spam Report):

2.png

  • Different custom heuristics implement to actively validate and seek for clues of spam categorization, here logic detecting Domain Impersonation:

3.png

  • Script attempts to reverse-engineer and document some of the Office365 Anti-Spam rules, as well as collect public knowledge about other opaque Anti-Spam headers:

4.png

Processed headers

Processed headers (more than 67+ headers are parsed):

  • X-forefront-antispam-report
  • X-exchange-antispam
  • X-exchange-antispam-mailbox-delivery
  • X-exchange-antispam-message-info
  • X-microsoft-antispam-report-cfa-test
  • Received
  • From
  • To
  • Subject
  • Thread-topic
  • Received-spf
  • X-mailer
  • X-originating-ip
  • User-agent
  • X-forefront-antispam-report
  • X-microsoft-antispam-mailbox-delivery
  • X-microsoft-antispam
  • X-exchange-antispam-report-cfa-test
  • X-spam-status
  • X-spam-level
  • X-spam-flag
  • X-spam-report
  • X-vr-spamcause
  • X-ovh-spam-reason
  • X-vr-spamscore
  • X-virus-scanned
  • X-spam-checker-version
  • X-ironport-av
  • X-ironport-anti-spam-filtered
  • X-ironport-anti-spam-result
  • X-mimecast-spam-score
  • Spamdiagnosticmetadata
  • X-ms-exchange-atpmessageproperties
  • X-msfbl
  • X-ms-exchange-transport-endtoendlatency
  • X-ms-oob-tlc-oobclassifiers
  • X-ip-spam-verdict
  • X-amp-result
  • X-ironport-remoteip
  • X-ironport-reputation
  • X-sbrs
  • X-ironport-sendergroup
  • X-policy
  • X-ironport-mailflowpolicy
  • X-remote-ip
  • X-sea-spam
  • X-fireeye
  • X-antiabuse
  • X-tmase-version
  • X-tm-as-product-ver
  • X-tm-as-result
  • X-imss-scan-details
  • X-tm-as-user-approved-sender
  • X-tm-as-user-blocked-sender
  • X-tmase-result
  • X-tmase-snap-result
  • X-imss-dkim-white-list
  • X-tm-as-result-xfilter
  • X-tm-as-smtp
  • X-scanned-by
  • X-mimecast-spam-signature
  • X-mimecast-bulk-signature
  • X-sender-ip
  • X-forefront-antispam-report-untrusted
  • X-microsoft-antispam-untrusted
  • X-sophos-senderhistory
  • X-sophos-rescan

Most of these headers are not fully documented, therefore the script is unable to pinpoint all the details, but at least it collects all I could find on them.

Usage

Help:

PS> py .\decode-spam-headers.py --help
usage: decode-spam-headers.py [options] <file>

optional arguments:
  -h, --help            show this help message and exit

Required arguments:
  infile                Input file to be analysed

Options:
  -o OUTFILE, --outfile OUTFILE
                        Output file with report
  -f {json,text}, --format {json,text}
                        Analysis report format. JSON, text. Default: text
  -N, --nocolor         Dont use colors in text output.
  -v, --verbose         Verbose mode.
  -d, --debug           Debug mode.

Tests:
  -r, --resolve         Resolve IPv4 addresses / Domain names.
  -a, --decode-all      Decode all =?us-ascii?Q? mail encoded messages and print their contents.

Sample run

Sample run:

  PS> py decode-spam-headers.py headers.txt

------------------------------------------
(1) Test: Received - Mail Servers Flow

HEADER:
    Received

VALUE:
    ...

ANALYSIS:
    - List of server hops used to deliver message:

          --> (1) "attacker" <attacker@attacker.com>

               |_> (2) SMTP-SERVICE (44.55.66.77)
                      time: 01 Jan 2021 12:34:20

                  |_> (3) mail-wr1-f51.google.com (209.85.221.51)
                          time: 01 Jan 2021 12:34:20
                          version: fuzzy match: Exchange Server 2019 CU11; October 12, 2021; 15.2.986.9

                      |_> (4) SN1NAM02FT0061.eop-nam02.prod.protection.outlook.com (2603:10b6:806:131:cafe::e5)
                              time: 01 Jan 2021 12:34:20
                              version: fuzzy match: Exchange Server 2019 CU11; October 12, 2021; 15.2.986.9

                          |_> (5) SA0PR11CA0138.namprd11.prod.outlook.com (2603:10b6:806:131::23)
                                  time: 01 Jan 2021 12:34:20
                                  version: fuzzy match: Exchange Server 2019 CU11; October 12, 2021; 15.2.986.9

                              |_> (6) CP2PR80MB4114.lamprd80.prod.outlook.com (2603:10d6:102:3c::15)
                                      time: 01 Jan 2021 12:34:23

                                  |_> (7) "Victim Surname" <victim@contoso.com>



------------------------------------------

[...]

------------------------------------------
(4) Test: Mail Client Version

HEADER:
    X-Mailer

VALUE:
    OEM

ANALYSIS:
    - X-Mailer header was present and contained value: "OEM".


------------------------------------------
(5) Test: X-Forefront-Antispam-Report

HEADER:
    X-Forefront-Antispam-Report

VALUE:
    CIP:209.85.167.100;CTRY:US;LANG:de;SCL:5;SRV:;IPV:NLI;SFV:SPM;H:mail-lf1-f100.google.com;PTR:mail-l
    f1-f100.google.com;CAT:DIMP;SFTY:9.19;SFS:(4636009)(956004)(166002)(6916009)(356005)(336012)(19
    625305002)(22186003)(5660300002)(4744005)(6666004)(35100500006)(82960400001)(26005)(7596003)(7636003)(554460
    02)(224303003)(1096003)(58800400005)(86362001)(9686003)(43540500002);DIR:INB;SFTY:9.19;

ANALYSIS:
    - Microsoft Office365/Exchange ForeFront Anti-Spam report

        - CIP: Connecting IP address: 209.85.167.100

        - CTRY: The source country as determined by the connecting IP address
                - US

        - LANG: The language in which the message was written
                - de

        - IPV: Ingress Peer Verification status
                - NLI: The IP address was not found on any IP reputation list.

        - SFV: Message Filtering
                - SPM: The message was marked as spam by spam filtering.

        - H: The HELO or EHLO string of the connecting email server.
                - mail-lf1-f100.google.com

        - PTR: Reverse DNS of the Connecting IP peer's address
                - mail-lf1-f100.google.com

        - CAT: The category of protection policy
                - DIMP: Domain Impersonation

        - SFTY: The message was identified as phishing
                - 9.19: Domain impersonation. The sending domain is attempting to impersonate a protected domain

        - DIR: Direction of email verification
                - INB: Inbound email verification

        - Message matched 24 Anti-Spam rules (SFS):
                - (1096003)
                - (166002)
                - (19625305002)
                - (22186003)
                - (224303003)
                - (26005)
                - (336012)
                - (356005)
                - (35100500006)         - (SPAM) Message contained embedded image.
                - (43540500002)
                - (4636009)
                - (4744005)
                - (55446002)
                - (5660300002)
                - (58800400005)
                - (6666004)
                - (6916009)
                - (7596003)
                - (7636003)
                - (82960400001)
                - (86362001)
                - (956004)
                - (9686003)

        - SCL: Spam Confidence Level: 5
                - SPAM: Spam filtering marked the message as Spam


More information:
        - https://docs.microsoft.com/en-us/microsoft-365/security/office-365-security/anti-spam-message-headers
        - https://docs.microsoft.com/en-us/exchange/antispam-and-antimalware/antispam-protection/antispam-stamps
        - https://docs.microsoft.com/en-us/microsoft-365/security/office-365-security/spam-confidence-levels
        - https://docs.microsoft.com/en-us/exchange/monitoring/trace-an-email-message/run-a-message-trace-and-view-results


------------------------------------------
(6) Test: X-Microsoft-Antispam-Mailbox-Delivery

HEADER:
    X-Microsoft-Antispam-Mailbox-Delivery

VALUE:
    ucf:0;jmr:1;auth:0;dest:J;ENG:(910001)(944506458)(944626604)(750132)(520011016);

ANALYSIS:
    - This header denotes what to do with received message, where to put it.

        - auth: Message originating from Authenticated sender
                - 0: Not Authenticated

        - dest: Destination where message should be placed
                - J: JUNK directory

        - Message matched 6 Anti-Spam Delivery rules:
                - (520011016)
                - (750132)
                - (910001)
                - (944506458)
                - (944626604)


------------------------------------------
(7) Test: X-Microsoft-Antispam Bulk Mail

HEADER:
    X-Microsoft-Antispam
VALUE:
    BCL:0;

ANALYSIS:
    - BCL: BULK Confidence Level: 0
        The message isn't from a bulk sender.

    More information:
                - https://docs.microsoft.com/en-us/microsoft-365/security/office-365-security/bulk-complaint-level-values

------------------------------------------

[...]

------------------------------------------
(10) Test: MS Defender ATP Message Properties

HEADER:
    X-MS-Exchange-AtpMessageProperties

VALUE:
    SA|SL

ANALYSIS:
    - MS Defender Advanced Threat Protection enabled following protections on this message:
        - Safe Attachments Protection
        - Safe Links Protection


------------------------------------------
(11) Test: Domain Impersonation

HEADER:
    From

VALUE:
    "attacker" <attacker@attacker.com>

ANALYSIS:
    - Mail From: <attacker@attacker.com>

                - Mail Domain: attacker.com
                       --> resolves to: 11.22.33.44
                           --> reverse-DNS resolves to: ec2-11-22-33-44.eu-west-3.compute.amazonaws.com
                               (sender's domain: amazonaws.com)

                - First Hop:   SMTP-SERVICE (44.55.66.77)
                       --> resolves to:
                           --> reverse-DNS resolves to: host44-55-66-77.static.arubacloud.pl
                               (first hop's domain: arubacloud.pl)

        - Domain SPF: "v=spf1 include:_spf.google.com ~all"

        - WARNING! Potential Domain Impersonation!
                - Mail's domain should resolve to:      amazonaws.com
                - But instead first hop resolved to:    arubacloud.pl