Brand impersonation: Sharepoint

  1name: "Brand impersonation: Sharepoint"
  2description: |
  3    Body, attached images or pdf contains a Sharepoint logo. The message contains a link and credential theft language.
  4type: "rule"
  5severity: "high"
  6source: |
  7  type.inbound
  8  and length(body.links) > 0
  9  and (
 10    any(attachments,
 11        (.file_type in $file_types_images or .file_type == "pdf")
 12        and any(ml.logo_detect(.).brands, .name == "Microsoft SharePoint")
 13    )
 14    or any(ml.logo_detect(file.message_screenshot()).brands,
 15           .name == "Microsoft SharePoint"
 16    )
 17    or strings.istarts_with(strings.replace_confusables(body.current_thread.text),
 18                            "Sharepoint"
 19    )
 20    or regex.icontains(body.html.raw,
 21                       '<img.*(title=|alt=).share.*src=""'
 22    ) // broken Sharepoint logo
 23    or (
 24      strings.icontains(strings.replace_confusables(body.plain.raw), "SharePoint")
 25      // message body references file deletion
 26      and regex.icontains(body.plain.raw,
 27                          '(expired )?file\s(was|has been|will be|scheduled (for|to be))\s?delet(ed|ion)'
 28      )
 29    )
 30  )
 31  and (
 32    (
 33      any(ml.nlu_classifier(body.current_thread.text).intents,
 34          .name == "cred_theft" and .confidence == "high"
 35      )
 36      //
 37      // This rule makes use of a beta feature and is subject to change without notice
 38      // using the beta feature in custom rules is not suggested until it has been formally released
 39      //
 40      or any(ml.nlu_classifier(beta.ocr(file.message_screenshot()).text).intents,
 41             .name == "cred_theft" and .confidence == "high"
 42      )
 43    )
 44    or any(ml.nlu_classifier(body.current_thread.text).entities,
 45           .name == "urgency" and strings.ilike(.text, "*encrypted*")
 46    )
 47    or any(body.links,
 48           regex.imatch(.display_text,
 49                        '(?:re)?view (?:(?:&|and) (?:e([[:punct:]]|\s)?)?sign )?(?:complete )?(?:document|file)'
 50           )
 51    )
 52  )
 53  and not (
 54    (
 55      (
 56        strings.istarts_with(subject.subject, "RE:")
 57        or strings.istarts_with(subject.subject, "R:")
 58        or strings.istarts_with(subject.subject, "ODG:")
 59        or strings.istarts_with(subject.subject, "答复:")
 60        or strings.istarts_with(subject.subject, "AW:")
 61        or strings.istarts_with(subject.subject, "TR:")
 62        or strings.istarts_with(subject.subject, "FWD:")
 63        or regex.imatch(subject.subject, '(\[[^\]]+\]\s?){0,3}(re|fwd?)\s?:')
 64        or regex.imatch(subject.subject,
 65                        '^\[?(EXT|EXTERNAL)\]?[: ]\s*(RE|FWD?|FW|AW|TR|ODG|答复):.*'
 66        )
 67      )
 68      and (
 69        (length(headers.references) > 0 or headers.in_reply_to is not null)
 70        // ensure that there are actual threads
 71        and (
 72          length(body.previous_threads) > 0
 73          or (length(body.html.display_text) - length(body.current_thread.text)) > 200
 74        )
 75      )
 76    )
 77  )
 78  and (
 79    profile.by_sender_email().prevalence != 'common'
 80    or not profile.by_sender_email().solicited
 81    or profile.by_sender().any_messages_malicious_or_spam
 82  )
 83  and not profile.by_sender().any_messages_benign
 84  
 85  // negate highly trusted sender domains unless they fail DMARC authentication
 86  and (
 87    (
 88      sender.email.domain.root_domain in $high_trust_sender_root_domains
 89      and not headers.auth_summary.dmarc.pass
 90    )
 91    or sender.email.domain.root_domain not in $high_trust_sender_root_domains
 92  )
 93  
 94  // negate sharepoint file share
 95  and not (
 96    // based on the message id format
 97    (
 98      (
 99        strings.starts_with(headers.message_id, '<Share-')
100        and strings.ends_with(headers.message_id, '@odspnotify>')
101      )
102      or // negate legitimate access request to file
103   (
104        strings.starts_with(headers.message_id, '<Sharing')
105        and strings.ends_with(headers.message_id, '@odspnotify>')
106      )
107      // deal with Google thinking the message ID is "broke"
108      or (
109        strings.icontains(headers.message_id, 'SMTPIN_ADDED_BROKEN')
110        and any(headers.hops,
111                any(.fields,
112                    .name == "X-Google-Original-Message-ID"
113                    and strings.starts_with(.value, '<Share-')
114                    and strings.ends_with(.value, '@odspnotify>')
115                )
116        )
117      )
118    )
119    // all of the "action" links are sharepoint/ms
120    and all(filter(body.links,
121                   strings.icontains(subject.subject, .display_text)
122                   or .display_text == "Open"
123            ),
124            .href_url.domain.root_domain in ("sharepoint.com")
125            or (
126              .href_url.domain.tld == "ms"
127              // Microsoft does not own the .ms TLD, this checks to ensure it is one of their domains
128              and (
129                network.whois(.href_url.domain).registrant_company == "Microsoft Corporation"
130                or strings.ilike(network.whois(.href_url.domain).registrar_name,
131                                 "*MarkMonitor*",
132                                 "*CSC Corporate*",
133                                 "*com laude*"
134                )
135              )
136            )
137    )
138  )  
139attack_types:
140  - "Credential Phishing"
141tactics_and_techniques:
142  - "Impersonation: Brand"
143  - "Social engineering"
144detection_methods:
145  - "Computer Vision"
146  - "Content analysis"
147  - "File analysis"
148  - "Natural Language Understanding"
149  - "Sender analysis"
150id: "284b1b70-8daa-5adf-9df8-15d4c6b5ead9"