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    or (
 31      strings.icontains(body.current_thread.text, 'Sharepoint')
 32      and (
 33        regex.icontains(body.html.raw, '{(?:domain|randomNumber\d?)}')
 34        or any(body.links,
 35               regex.icontains(.href_url.url, 'mailto:[^@]+@{domain}')
 36        )
 37        or regex.icontains(body.html.raw, '<title>[^<]*Easearch[^<]*</title>')
 38      )
 39    )
 40  )
 41  and (
 42    (
 43      any(ml.nlu_classifier(body.current_thread.text).intents,
 44          .name == "cred_theft" and .confidence == "high"
 45      )
 46      //
 47      // This rule makes use of a beta feature and is subject to change without notice
 48      // using the beta feature in custom rules is not suggested until it has been formally released
 49      //
 50      or any(ml.nlu_classifier(beta.ocr(file.message_screenshot()).text).intents,
 51             .name == "cred_theft" and .confidence == "high"
 52      )
 53    )
 54    or any(ml.nlu_classifier(body.current_thread.text).entities,
 55           .name == "urgency" and strings.ilike(.text, "*encrypted*")
 56    )
 57    or any(body.links,
 58           regex.imatch(.display_text,
 59                        '(?:re)?view (?:(?:&|and) (?:e([[:punct:]]|\s)?)?sign )?(?:complete )?(?:document|file)'
 60           )
 61    )
 62  )
 63  and not (
 64    (
 65      (
 66        strings.istarts_with(subject.subject, "RE:")
 67        or strings.istarts_with(subject.subject, "R:")
 68        or strings.istarts_with(subject.subject, "ODG:")
 69        or strings.istarts_with(subject.subject, "答复:")
 70        or strings.istarts_with(subject.subject, "AW:")
 71        or strings.istarts_with(subject.subject, "TR:")
 72        or strings.istarts_with(subject.subject, "FWD:")
 73        or regex.imatch(subject.subject, '(\[[^\]]+\]\s?){0,3}(re|fwd?)\s?:')
 74        or regex.imatch(subject.subject,
 75                        '^\[?(EXT|EXTERNAL)\]?[: ]\s*(RE|FWD?|FW|AW|TR|ODG|答复):.*'
 76        )
 77      )
 78      and (
 79        (length(headers.references) > 0 or headers.in_reply_to is not null)
 80        // ensure that there are actual threads
 81        and (
 82          length(body.previous_threads) > 0
 83          or (length(body.html.display_text) - length(body.current_thread.text)) > 200
 84        )
 85      )
 86    )
 87  )
 88  and (
 89    profile.by_sender_email().prevalence != 'common'
 90    or not profile.by_sender_email().solicited
 91    or profile.by_sender().any_messages_malicious_or_spam
 92  )
 93  and not profile.by_sender().any_messages_benign
 94  
 95  // negate highly trusted sender domains unless they fail DMARC authentication
 96  and (
 97    (
 98      sender.email.domain.root_domain in $high_trust_sender_root_domains
 99      and not headers.auth_summary.dmarc.pass
100    )
101    or sender.email.domain.root_domain not in $high_trust_sender_root_domains
102  )
103  
104  // negate sharepoint file share
105  and not (
106    // based on the message id format
107    (
108      (
109        strings.starts_with(headers.message_id, '<Share-')
110        and strings.ends_with(headers.message_id, '@odspnotify>')
111      )
112      // negate legitimate access request to file
113      or (
114        strings.starts_with(headers.message_id, '<Sharing')
115        and strings.ends_with(headers.message_id, '@odspnotify>')
116      )
117      // deal with Google thinking the message ID is "broke"
118      or (
119        strings.icontains(headers.message_id, 'SMTPIN_ADDED_BROKEN')
120        and any(headers.hops,
121                any(.fields,
122                    .name == "X-Google-Original-Message-ID"
123                    and strings.starts_with(.value, '<Share-')
124                    and strings.ends_with(.value, '@odspnotify>')
125                )
126        )
127      )
128    )
129    // all of the "action" links are sharepoint/ms
130    and all(filter(body.links,
131                   strings.icontains(subject.subject, .display_text)
132                   or .display_text == "Open"
133            ),
134            .href_url.domain.root_domain in ("sharepoint.com")
135            or (
136              .href_url.domain.tld == "ms"
137              // Microsoft does not own the .ms TLD, this checks to ensure it is one of their domains
138              and (
139                network.whois(.href_url.domain).registrant_company == "Microsoft Corporation"
140                or strings.ilike(network.whois(.href_url.domain).registrar_name,
141                                 "*MarkMonitor*",
142                                 "*CSC Corporate*",
143                                 "*com laude*"
144                )
145              )
146            )
147    )
148  )
149  // negate sharepoint file shares with mimecast rewrites
150  and not (
151    // rewritten message ID
152    strings.iends_with(headers.message_id, 'mimecast.lan>')
153    and all(filter(body.links,
154                   strings.icontains(subject.subject, .display_text)
155                   or .display_text == "Open"
156            ),
157            .href_url.domain.root_domain in (
158              "mimecastprotect.com",
159              "mimecast.com"
160            )
161            and any(.href_url.query_params_decoded["domain"],
162                    strings.parse_domain(.).tld == "ms"
163                    or strings.parse_domain(.).root_domain == "sharepoint.com"
164            )
165    )
166  )  
167attack_types:
168  - "Credential Phishing"
169tactics_and_techniques:
170  - "Impersonation: Brand"
171  - "Social engineering"
172detection_methods:
173  - "Computer Vision"
174  - "Content analysis"
175  - "File analysis"
176  - "Natural Language Understanding"
177  - "Sender analysis"
178id: "284b1b70-8daa-5adf-9df8-15d4c6b5ead9"