sublimelowRule

Spam: Sexually explicit content with emoji in subject from freemail provider

Detects messages from free email providers that contain sexually explicit content and include emojis in the subject line.

MITRE ATT&CK

T1566 T1598

initial-access

Detection Query

type.inbound
// sender is a freemail domain
and sender.email.domain.root_domain in $free_email_providers
// look for commonly used emojis in sexually explicit messages
and regex.icontains(subject.subject,
                    '(\x{1F346}|\x{1F608}|\x{1F609}|\x{1F351}|\x{2764}|\x{1F60D}|\x{1F618}|\x{1F48B}|\x{1F63B}|\x{1F445}|\x{1F51E}|\x{1F525}|\x{1F4F7})'
)
and any(ml.nlu_classifier(body.current_thread.text).topics,
        .name == 'Sexually Explicit Messages'
)

Data Sources

Email MessagesEmail HeadersEmail Attachments

Platforms

Raw Content

name: "Spam: Sexually explicit content with emoji in subject from freemail provider"
description: "Detects messages from free email providers that contain sexually explicit content and include emojis in the subject line."
type: "rule"
severity: "low"
source: |
  type.inbound
  // sender is a freemail domain
  and sender.email.domain.root_domain in $free_email_providers
  // look for commonly used emojis in sexually explicit messages
  and regex.icontains(subject.subject,
                      '(\x{1F346}|\x{1F608}|\x{1F609}|\x{1F351}|\x{2764}|\x{1F60D}|\x{1F618}|\x{1F48B}|\x{1F63B}|\x{1F445}|\x{1F51E}|\x{1F525}|\x{1F4F7})'
  )
  and any(ml.nlu_classifier(body.current_thread.text).topics,
          .name == 'Sexually Explicit Messages'
  )

attack_types:
  - "Spam"
tactics_and_techniques:
  - "Free email provider"
  - "Social engineering"
detection_methods:
  - "Content analysis"
  - "Header analysis"
  - "Natural Language Understanding"
  - "Sender analysis"
id: "4a2326d4-7f22-5a0c-9f91-6e302ee1987a"