Sublime Security medium experimental mql

Link: SharePoint OneNote or PDF link with self sender behavior

Detects messages where the sender and recipient are the same address, containing SharePoint links to OneNote or PDF files, with minimal attachments and non-standard message IDs indicating potential abuse of SharePoint services for malicious purposes.

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Detection Logic

type.inbound
// self sender
and length(recipients.to) == 1
and recipients.to[0].email.email == sender.email.email
// single link to sharepoint
and length(filter(body.current_thread.links,
                  .href_url.domain.root_domain == 'sharepoint.com'
                  // it is either a OneNote or PDF file, or unknown
                  and regex.icontains(.href_url.path,
                                      '\/:[obu]:\/(?:p
| g\/personal)'
                  )
           )
) == 1
// only one link to sharepoint
and length(filter(body.current_thread.links,
                  .href_url.domain.root_domain == 'sharepoint.com'
           )
) == 1
// not sent via sharepoint
and not strings.starts_with(headers.message_id, '<Share-')
and not strings.ends_with(headers.message_id, '@odspnotify>')
// 0 or 1 attachments (this reduces FPs which had many attachments)
and length(attachments) - length(filter(attachments,
                                        strings.contains(body.html.raw,
                                                         strings.concat('src="cid:',
                                                                        .content_id
                                                         )
                                        )
                                 )
) <= 1

Field Validations

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