Callback Phishing: SumUp Infrastructure Abuse

  1name: "Callback Phishing: SumUp Infrastructure Abuse"
  2description: "A fraudulent invoice/receipt found in the body of the message sent by exploiting SumUp's receipt email service."
  3type: "rule"
  4severity: "high"
  5source: |
  6  type.inbound
  7  and sender.email.domain.root_domain in ("sumup.com")
  8  and (
  9    strings.ilike(body.html.display_text, "*delivery note*")
 10    or strings.ilike(body.html.display_text, "*made with sumup*")
 11  )
 12  // keep in sync with https://github.com/sublime-security/sublime-rules/blob/main/detection-rules/paypal_invoice_abuse.yml
 13  and (
 14    (
 15      // icontains a phone number
 16      (
 17        regex.icontains(strings.replace_confusables(body.current_thread.text),
 18                        '.*\+?([ilo0-9]{1}.)?\(?[ilo0-9]{3}?\)?.[ilo0-9]{3}.?[ilo0-9]{4}.*\n'
 19        )
 20        or regex.icontains(strings.replace_confusables(body.current_thread.text),
 21                           '.*\+[ilo0-9]{1,3}[ilo0-9]{10}.*\n'
 22        )
 23        or // +12028001238
 24   regex.icontains(strings.replace_confusables(body.current_thread.text),
 25                   '.*[ilo0-9]{3}\.[ilo0-9]{3}\.[ilo0-9]{4}.*\n'
 26        )
 27        or // 202-800-1238
 28   regex.icontains(strings.replace_confusables(body.current_thread.text),
 29                   '.*[ilo0-9]{3}-[ilo0-9]{3}-[ilo0-9]{4}.*\n'
 30        )
 31        or // (202) 800-1238
 32   regex.icontains(strings.replace_confusables(body.current_thread.text),
 33                   '.*\([ilo0-9]{3}\)\s[ilo0-9]{3}-[ilo0-9]{4}.*\n'
 34        )
 35        or // (202)-800-1238
 36   regex.icontains(strings.replace_confusables(body.current_thread.text),
 37                   '.*\([ilo0-9]{3}\)-[ilo0-9]{3}-[ilo0-9]{4}.*\n'
 38        )
 39        or ( // 8123456789
 40          regex.icontains(strings.replace_confusables(body.current_thread.text),
 41                          '.*8[ilo0-9]{9}.*\n'
 42          )
 43          and regex.icontains(strings.replace_confusables(body.current_thread.text
 44                              ),
 45                              '\+[1l]'
 46          )
 47        )
 48      )
 49      and (
 50        (
 51          4 of (
 52            strings.ilike(body.html.inner_text, '*you did not*'),
 53            strings.ilike(body.html.inner_text, '*is not for*'),
 54            strings.ilike(body.html.inner_text, '*done by you*'),
 55            regex.icontains(body.html.inner_text, "didn\'t ma[kd]e this"),
 56            strings.ilike(body.html.inner_text, '*Fruad Alert*'),
 57            strings.ilike(body.html.inner_text, '*Fraud Alert*'),
 58            strings.ilike(body.html.inner_text, '*fraudulent*'),
 59            strings.ilike(body.html.inner_text, '*using your PayPal*'),
 60            strings.ilike(body.html.inner_text, '*subscription*'),
 61            strings.ilike(body.html.inner_text, '*antivirus*'),
 62            strings.ilike(body.html.inner_text, '*order*'),
 63            strings.ilike(body.html.inner_text, '*support*'),
 64            strings.ilike(body.html.inner_text, '*sincerely apologize*'),
 65            strings.ilike(body.html.inner_text, '*receipt*'),
 66            strings.ilike(body.html.inner_text, '*invoice*'),
 67            strings.ilike(body.html.inner_text, '*Purchase*'),
 68            strings.ilike(body.html.inner_text, '*transaction*'),
 69            strings.ilike(body.html.inner_text, '*Market*Value*'),
 70            strings.ilike(body.html.inner_text, '*BTC*'),
 71            strings.ilike(body.html.inner_text, '*call*'),
 72            strings.ilike(body.html.inner_text, '*get in touch with our*'),
 73            strings.ilike(body.html.inner_text, '*quickly inform*'),
 74            strings.ilike(body.html.inner_text, '*quickly reach *'),
 75            strings.ilike(body.html.inner_text, '*detected unusual transactions*'),
 76            strings.ilike(body.html.inner_text, '*without your authorization*'),
 77            strings.ilike(body.html.inner_text, '*cancel*'),
 78            strings.ilike(body.html.inner_text, '*renew*'),
 79            strings.ilike(body.html.inner_text, '*refund*'),
 80            strings.ilike(body.html.inner_text, '*+1*'),
 81            regex.icontains(body.html.inner_text, 'help.{0,3}desk'),
 82            strings.ilike(body.html.inner_text, '* your funds*'),
 83            strings.ilike(body.html.inner_text, '* your checking*'),
 84            strings.ilike(body.html.inner_text, '* your saving*'),
 85            strings.ilike(body.html.inner_text, '*transfer*'),
 86            strings.ilike(body.html.inner_text, '*secure your account*'),
 87            strings.ilike(body.html.inner_text, '*recover your*'),
 88            strings.ilike(body.html.inner_text, '*unusual activity*'),
 89            strings.ilike(body.html.inner_text, '*suspicious transaction*'),
 90            strings.ilike(body.html.inner_text, '*transaction history*'),
 91            strings.ilike(body.html.inner_text, '*please ignore this*'),
 92            strings.ilike(body.html.inner_text, '*report activity*'),
 93          )
 94        )
 95        or regex.icontains(body.current_thread.text,
 96                           'note from.{0,50}(?:call|reach|contact|paypal)'
 97        )
 98        or any(ml.nlu_classifier(body.current_thread.text).intents,
 99               .name == "callback_scam"
100        )
101        or (
102          // Unicode confusables words obfuscated in note
103          regex.icontains(body.html.inner_text,
104                          '\+𝟭|𝗽𝗮𝘆𝗺𝗲𝗻𝘁|𝗛𝗲𝗹𝗽 𝗗𝗲𝘀𝗸|𝗿𝗲𝗳𝘂𝗻𝗱|𝗮𝗻𝘁𝗶𝘃𝗶𝗿𝘂𝘀|𝗰𝗮𝗹𝗹|𝗰𝗮𝗻𝗰𝗲𝗹'
105          )
106        )
107        or strings.ilike(body.html.inner_text, '*kindly*')
108      )
109    )
110  )
111    
112
113attack_types:
114  - "BEC/Fraud"
115  - "Callback Phishing"
116tactics_and_techniques:
117  - "Evasion"
118  - "Social engineering"
119detection_methods:
120  - "Content analysis"
121  - "Header analysis"
122  - "Sender analysis"
123id: "1c41649e-d701-513e-a676-20f48e834a7b"