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This commit is contained in:
Mariusz B. / mgeeky
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## `decode-spam-headers.py`
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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.
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This script also extracts all IPv4 addresses and domain names and performs full DNS resolution of them.
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Resulting output will contain useful information on why this e-mail might have been blocked.
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### Example screenshots
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- Chain of MTA servers (nicely parsed `Received` headers):
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- Various headers decoded as much as possible, according to publicly available documentation (here _Office365 ForeFront Spam Report_):
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- Different custom heuristics implement to actively validate and seek for clues of spam categorization, here logic detecting _Domain Impersonation_:
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- 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:
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### Processed headers
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Processed headers (more than **67+** headers are parsed):
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- `X-forefront-antispam-report`
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- `X-exchange-antispam`
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- `X-exchange-antispam-mailbox-delivery`
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- `X-exchange-antispam-message-info`
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- `X-microsoft-antispam-report-cfa-test`
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- `Received`
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- `From`
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- `To`
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- `Subject`
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- `Thread-topic`
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- `Received-spf`
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- `X-mailer`
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- `X-originating-ip`
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- `User-agent`
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- `X-forefront-antispam-report`
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- `X-microsoft-antispam-mailbox-delivery`
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- `X-microsoft-antispam`
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- `X-exchange-antispam-report-cfa-test`
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- `X-spam-status`
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- `X-spam-level`
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- `X-spam-flag`
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- `X-spam-report`
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- `X-vr-spamcause`
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- `X-ovh-spam-reason`
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- `X-vr-spamscore`
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- `X-virus-scanned`
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- `X-spam-checker-version`
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- `X-ironport-av`
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- `X-ironport-anti-spam-filtered`
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- `X-ironport-anti-spam-result`
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- `X-mimecast-spam-score`
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- `Spamdiagnosticmetadata`
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- `X-ms-exchange-atpmessageproperties`
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- `X-msfbl`
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- `X-ms-exchange-transport-endtoendlatency`
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- `X-ms-oob-tlc-oobclassifiers`
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- `X-ip-spam-verdict`
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- `X-amp-result`
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- `X-ironport-remoteip`
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- `X-ironport-reputation`
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- `X-sbrs`
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- `X-ironport-sendergroup`
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- `X-policy`
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- `X-ironport-mailflowpolicy`
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- `X-remote-ip`
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- `X-sea-spam`
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- `X-fireeye`
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- `X-antiabuse`
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- `X-tmase-version`
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- `X-tm-as-product-ver`
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- `X-tm-as-result`
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- `X-imss-scan-details`
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- `X-tm-as-user-approved-sender`
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- `X-tm-as-user-blocked-sender`
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- `X-tmase-result`
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- `X-tmase-snap-result`
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- `X-imss-dkim-white-list`
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- `X-tm-as-result-xfilter`
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- `X-tm-as-smtp`
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- `X-scanned-by`
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- `X-mimecast-spam-signature`
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- `X-mimecast-bulk-signature`
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- `X-sender-ip`
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- `X-forefront-antispam-report-untrusted`
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- `X-microsoft-antispam-untrusted`
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- `X-sophos-senderhistory`
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- `X-sophos-rescan`
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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.
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### Usage
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Help:
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```
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PS> py .\decode-spam-headers.py --help
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usage: decode-spam-headers.py [options] <file>
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optional arguments:
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-h, --help show this help message and exit
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Required arguments:
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infile Input file to be analysed or --list tests to show available tests.
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Options:
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-o OUTFILE, --outfile OUTFILE
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Output file with report
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-f {json,text}, --format {json,text}
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Analysis report format. JSON, text. Default: text
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-N, --nocolor Dont use colors in text output.
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-v, --verbose Verbose mode.
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-d, --debug Debug mode.
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-l, --list List available tests and quit. Use it like so: --list tests
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Tests:
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-i tests, --include-tests tests
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Comma-separated list of test IDs to run. Ex. --include-tests 1,3,7
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-e tests, --exclude-tests tests
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Comma-separated list of test IDs to skip. Ex. --exclude-tests 1,3,7
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-r, --resolve Resolve IPv4 addresses / Domain names.
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-a, --decode-all Decode all =?us-ascii?Q? mail encoded messages and print their contents.
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```
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If you want to run only a subset of tests, you'll first need to learn Test IDs of which to pick.
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Run the script with `-l tests` to grab that list.
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List available test and their corresponding IDs:
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```
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C:\> py decode-spam-headers.py -l tests
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[.] Available tests:
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TEST_ID - TEST_NAME
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--------------------------------------
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1 - Received - Mail Servers Flow
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2 - Extracted IP addresses
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3 - Extracted Domains
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4 - Bad Keywords In Headers
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5 - From Address Analysis
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6 - Subject and Thread Topic Difference
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7 - Authentication-Results
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8 - ARC-Authentication-Results
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9 - Received-SPF
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10 - Mail Client Version
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11 - User-Agent Version
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12 - X-Forefront-Antispam-Report
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13 - X-MS-Exchange-Organization-SCL
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14 - X-Microsoft-Antispam-Mailbox-Delivery
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15 - X-Microsoft-Antispam Bulk Mail
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16 - X-Exchange-Antispam-Report-CFA-Test
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17 - Domain Impersonation
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18 - SpamAssassin Spam Status
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19 - SpamAssassin Spam Level
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20 - SpamAssassin Spam Flag
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21 - SpamAssassin Spam Report
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22 - OVH's X-VR-SPAMCAUSE
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23 - OVH's X-Ovh-Spam-Reason
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24 - OVH's X-Ovh-Spam-Score
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25 - X-Virus-Scan
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26 - X-Spam-Checker-Version
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27 - X-IronPort-AV
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28 - X-IronPort-Anti-Spam-Filtered
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29 - X-IronPort-Anti-Spam-Result
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30 - X-Mimecast-Spam-Score
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31 - Spam Diagnostics Metadata
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32 - MS Defender ATP Message Properties
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33 - Message Feedback Loop
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34 - End-to-End Latency - Message Delivery Time
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35 - X-MS-Oob-TLC-OOBClassifiers
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36 - X-IP-Spam-Verdict
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37 - X-Amp-Result
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38 - X-IronPort-RemoteIP
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39 - X-IronPort-Reputation
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40 - X-SBRS
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41 - X-IronPort-SenderGroup
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42 - X-Policy
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43 - X-IronPort-MailFlowPolicy
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44 - X-SEA-Spam
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45 - X-FireEye
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46 - X-AntiAbuse
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47 - X-TMASE-Version
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48 - X-TM-AS-Product-Ver
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49 - X-TM-AS-Result
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50 - X-IMSS-Scan-Details
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51 - X-TM-AS-User-Approved-Sender
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52 - X-TM-AS-User-Blocked-Sender
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53 - X-TMASE-Result
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54 - X-TMASE-SNAP-Result
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55 - X-IMSS-DKIM-White-List
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56 - X-TM-AS-Result-Xfilter
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57 - X-TM-AS-SMTP
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58 - X-TMASE-SNAP-Result
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59 - X-TM-Authentication-Results
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60 - X-Scanned-By
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61 - X-Mimecast-Spam-Signature
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62 - X-Mimecast-Bulk-Signature
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63 - X-Forefront-Antispam-Report-Untrusted
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64 - X-Microsoft-Antispam-Untrusted
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65 - X-Mimecast-Impersonation-Protect
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66 - X-Proofpoint-Spam-Details
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67 - X-Proofpoint-Virus-Version
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68 - SPFCheck
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69 - X-Barracuda-Spam-Score
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70 - X-Barracuda-Spam-Status
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71 - X-Barracuda-Spam-Report
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72 - X-Barracuda-Bayes
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73 - X-Barracuda-Start-Time
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74 - Similar to SpamAssassin Spam Level headers
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75 - SMTP Header Contained IP address
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76 - Other unrecognized Spam Related Headers
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77 - Other interesting headers
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78 - Security Appliances Spotted
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79 - Email Providers Infrastructure Clues
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80 - X-Microsoft-Antispam-Message-Info
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81 - Decoded Mail-encoded header values
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82 - Header Containing Client IP
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```
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### Sample run
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Sample run:
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```
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PS> py decode-spam-headers.py headers.txt
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------------------------------------------
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(1) Test: Received - Mail Servers Flow
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HEADER:
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Received
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VALUE:
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...
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ANALYSIS:
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- List of server hops used to deliver message:
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--> (1) "attacker" <attacker@attacker.com>
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|_> (2) SMTP-SERVICE (44.55.66.77)
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time: 01 Jan 2021 12:34:20
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|_> (3) mail-wr1-f51.google.com (209.85.221.51)
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time: 01 Jan 2021 12:34:20
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version: fuzzy match: Exchange Server 2019 CU11; October 12, 2021; 15.2.986.9
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|_> (4) SN1NAM02FT0061.eop-nam02.prod.protection.outlook.com (2603:10b6:806:131:cafe::e5)
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time: 01 Jan 2021 12:34:20
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version: fuzzy match: Exchange Server 2019 CU11; October 12, 2021; 15.2.986.9
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|_> (5) SA0PR11CA0138.namprd11.prod.outlook.com (2603:10b6:806:131::23)
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time: 01 Jan 2021 12:34:20
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version: fuzzy match: Exchange Server 2019 CU11; October 12, 2021; 15.2.986.9
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|_> (6) CP2PR80MB4114.lamprd80.prod.outlook.com (2603:10d6:102:3c::15)
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time: 01 Jan 2021 12:34:23
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|_> (7) "Victim Surname" <victim@contoso.com>
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------------------------------------------
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[...]
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------------------------------------------
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(4) Test: Mail Client Version
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HEADER:
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X-Mailer
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VALUE:
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OEM
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ANALYSIS:
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- X-Mailer header was present and contained value: "OEM".
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------------------------------------------
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(5) Test: X-Forefront-Antispam-Report
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HEADER:
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X-Forefront-Antispam-Report
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VALUE:
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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
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f1-f100.google.com;CAT:DIMP;SFTY:9.19;SFS:(4636009)(956004)(166002)(6916009)(356005)(336012)(19
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625305002)(22186003)(5660300002)(4744005)(6666004)(35100500006)(82960400001)(26005)(7596003)(7636003)(554460
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02)(224303003)(1096003)(58800400005)(86362001)(9686003)(43540500002);DIR:INB;SFTY:9.19;
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ANALYSIS:
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- Microsoft Office365/Exchange ForeFront Anti-Spam report
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- CIP: Connecting IP address: 209.85.167.100
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- CTRY: The source country as determined by the connecting IP address
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- US
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- LANG: The language in which the message was written
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- de
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- IPV: Ingress Peer Verification status
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- NLI: The IP address was not found on any IP reputation list.
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- SFV: Message Filtering
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- SPM: The message was marked as spam by spam filtering.
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- H: The HELO or EHLO string of the connecting email server.
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- mail-lf1-f100.google.com
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- PTR: Reverse DNS of the Connecting IP peer's address
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- mail-lf1-f100.google.com
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- CAT: The category of protection policy
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- DIMP: Domain Impersonation
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- SFTY: The message was identified as phishing
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- 9.19: Domain impersonation. The sending domain is attempting to impersonate a protected domain
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- DIR: Direction of email verification
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- INB: Inbound email verification
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- Message matched 24 Anti-Spam rules (SFS):
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- (1096003)
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- (166002)
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- (19625305002)
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- (22186003)
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- (224303003)
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- (26005)
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- (336012)
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- (356005)
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- (35100500006) - (SPAM) Message contained embedded image.
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- (43540500002)
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- (4636009)
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- (4744005)
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- (55446002)
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- (5660300002)
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- (58800400005)
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- (6666004)
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- (6916009)
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- (7596003)
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- (7636003)
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- (82960400001)
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- (86362001)
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- (956004)
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- (9686003)
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- SCL: Spam Confidence Level: 5
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- SPAM: Spam filtering marked the message as Spam
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More information:
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- https://docs.microsoft.com/en-us/microsoft-365/security/office-365-security/anti-spam-message-headers
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- https://docs.microsoft.com/en-us/exchange/antispam-and-antimalware/antispam-protection/antispam-stamps
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- https://docs.microsoft.com/en-us/microsoft-365/security/office-365-security/spam-confidence-levels
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- https://docs.microsoft.com/en-us/exchange/monitoring/trace-an-email-message/run-a-message-trace-and-view-results
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------------------------------------------
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(6) Test: X-Microsoft-Antispam-Mailbox-Delivery
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HEADER:
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X-Microsoft-Antispam-Mailbox-Delivery
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VALUE:
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ucf:0;jmr:1;auth:0;dest:J;ENG:(910001)(944506458)(944626604)(750132)(520011016);
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ANALYSIS:
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- This header denotes what to do with received message, where to put it.
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- auth: Message originating from Authenticated sender
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- 0: Not Authenticated
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- dest: Destination where message should be placed
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- J: JUNK directory
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- Message matched 6 Anti-Spam Delivery rules:
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- (520011016)
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- (750132)
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- (910001)
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- (944506458)
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- (944626604)
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------------------------------------------
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(7) Test: X-Microsoft-Antispam Bulk Mail
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HEADER:
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X-Microsoft-Antispam
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VALUE:
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BCL:0;
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ANALYSIS:
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- BCL: BULK Confidence Level: 0
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The message isn't from a bulk sender.
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More information:
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- https://docs.microsoft.com/en-us/microsoft-365/security/office-365-security/bulk-complaint-level-values
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------------------------------------------
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[...]
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------------------------------------------
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(10) Test: MS Defender ATP Message Properties
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HEADER:
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X-MS-Exchange-AtpMessageProperties
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VALUE:
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SA|SL
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ANALYSIS:
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- MS Defender Advanced Threat Protection enabled following protections on this message:
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- Safe Attachments Protection
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- Safe Links Protection
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------------------------------------------
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(11) Test: Domain Impersonation
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HEADER:
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From
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VALUE:
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"attacker" <attacker@attacker.com>
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ANALYSIS:
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- Mail From: <attacker@attacker.com>
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- Mail Domain: attacker.com
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--> resolves to: 11.22.33.44
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--> reverse-DNS resolves to: ec2-11-22-33-44.eu-west-3.compute.amazonaws.com
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(sender's domain: amazonaws.com)
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- First Hop: SMTP-SERVICE (44.55.66.77)
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--> resolves to:
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--> reverse-DNS resolves to: host44-55-66-77.static.arubacloud.pl
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(first hop's domain: arubacloud.pl)
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- Domain SPF: "v=spf1 include:_spf.google.com ~all"
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- WARNING! Potential Domain Impersonation!
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- Mail's domain should resolve to: amazonaws.com
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- But instead first hop resolved to: arubacloud.pl
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```
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@ -0,0 +1,70 @@
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#!/usr/bin/python3
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import os, sys, re
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import string
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import argparse
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import json
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import textwrap
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import socket
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import time
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import glob
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import base64
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rules = {}
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scanned = set()
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def walk(path):
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global rules
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global scanned
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print(f'Walking {path}...')
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|
||||
for file in glob.glob(os.path.join(path, '**'), recursive=True):
|
||||
if not file.lower().endswith('.txt'):
|
||||
continue
|
||||
|
||||
if file in scanned: continue
|
||||
scanned.add(file)
|
||||
|
||||
data = ''
|
||||
with open(file) as f:
|
||||
data = f.read()
|
||||
|
||||
for m in re.finditer(r'(\(\d{4,}\))', data, re.I):
|
||||
rule = m.group(1)
|
||||
|
||||
if rule in rules.keys():
|
||||
if file not in rules[rule]['files']:
|
||||
rules[rule]['count'] += 1
|
||||
rules[rule]['files'].add(file)
|
||||
else:
|
||||
rules[rule] = {}
|
||||
rules[rule]['count'] = 1
|
||||
rules[rule]['files'] = set([file, ])
|
||||
|
||||
def main(argv):
|
||||
|
||||
paths = []
|
||||
for i in range(len(argv)):
|
||||
arg = argv[i]
|
||||
if i == 0: continue
|
||||
|
||||
if not os.path.isdir(arg):
|
||||
print('[!] input path does not exist or is not a dir! ' + arg)
|
||||
sys.exit(1)
|
||||
|
||||
walk(os.path.abspath(arg))
|
||||
|
||||
print(f'[.] Found {len(rules)} unique rules.:')
|
||||
|
||||
candidates = []
|
||||
for k, v in rules.items():
|
||||
if v['count'] > 1:
|
||||
print(f'\n\t- {k: <15}: occurences: {v["count"]} - files: {len(v["files"])}')
|
||||
|
||||
if len(v['files']) < 6:
|
||||
for f in v['files']:
|
||||
print('\t\t- ' + str(f))
|
||||
|
||||
if __name__ == '__main__':
|
||||
main(sys.argv)
|
||||
File diff suppressed because it is too large
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Reference in New Issue