Sync from PR#2159

Create spam_google_group_invite.yml by @zoomequipd
#2159
Source SHA 88db12f
Triggered by @zoomequipd

detection-rules/spam_google_group_invite.yml

@@ -0,0 +1,15 @@
+name: "Spam: Google Groups Invitations"
+description: "Detects suspicious Google Groups invitations containing inappropriate content or suspicious patterns. The rule looks for invites from non-organizational domains that contain random alphanumeric strings, explicit keywords, or suspicious call-to-action phrases in the group names or descriptions."
+type: "rule"
+severity: "low"
+source: "type.inbound\n// \n//  Warning: This rule contains sexually explict keywords\n// \nand sender.email.email == \"[email protected]\"\nand (\n  strings.istarts_with(subject.subject, 'Invitation to join ')\n  or strings.istarts_with(subject.subject, 'You have been added to ')\n)\n// the invite is not from an $org_domain user\nand not any($org_domains,\n            strings.icontains(body.current_thread.text,\n                              strings.concat('@',\n                                             .,\n                                             ' invited you to join the '\n                              )\n            )\n            or strings.icontains(body.current_thread.text,\n                                 strings.concat('@', ., ' added you to the ')\n            )\n)\nand (\n    // the group name contains 7 char sets at the start and end and must contain a number\n    regex.icontains(subject.subject,\n                    '(?:added to|to join) [A-Z0-9]{6,7} .*(?:[[:^ascii:]]|[[:^alpha:]]) [A-Z0-9]{6,7}$'\n    )\n    // calls to action in the group name\n    or regex.icontains(subject.subject,\n                       '(?:added to|to join) .*(join|(?:click|go|tap) here)'\n    )\n    // it contains an emoji in the group name\n    or regex.icontains(subject.subject,\n                       '(?:added to|to join) .*[\\x{1F300}-\\x{1F5FF}\\x{1F600}-\\x{1F64F}\\x{1F680}-\\x{1F6FF}\\x{1F700}-\\x{1F77F}\\x{1F780}-\\x{1F7FF}\\x{1F900}-\\x{1F9FF}\\x{2600}-\\x{26FF}\\x{2700}-\\x{27BF}\\x{2300}-\\x{23FF}]'\n    )\n    or \n    regex.icontains(body.current_thread.text, '(?:about this group|message from).*(?:sex|horny|cock|fuck|ass|pussy|dick|tits|cum).*https?://')\n)\n"
+attack_types:
+  - "Spam"
+tactics_and_techniques:
+  - "Free email provider"
+detection_methods:
+  - "Content analysis"
+  - "Sender analysis"
+id: "4e0bec29-be9c-526f-ad56-824b4d87f55d"
+testing_pr: 2159
+testing_sha: 88db12fe0e212220660632ddd9078eaafe7d091c