sublimemediumRule

Brand impersonation: Gusto

Impersonation of Gusto, a cloud-based payroll management company.

MITRE ATT&CK

T1566 T1566.001 T1566.002 T1598 T1598.003 T1583.001

initial-access

Detection Query

type.inbound
and (
  strings.ilike(sender.display_name, '*gusto*')
  or strings.ilevenshtein(sender.display_name, 'gusto') <= 1
  or strings.ilike(sender.email.domain.domain, '*gusto*')
)
and any(ml.logo_detect(file.message_screenshot()).brands,
        .name == "Gusto" and .confidence in ("medium", "high")
)
and sender.email.domain.root_domain !~ 'gusto.com'

// negate highly trusted sender domains unless they fail DMARC authentication
and (
  (
    sender.email.domain.root_domain in $high_trust_sender_root_domains
    and not headers.auth_summary.dmarc.pass
  )
  or sender.email.domain.root_domain not in $high_trust_sender_root_domains
)

Data Sources

Email MessagesEmail HeadersEmail Attachments

Platforms

Raw Content

name: "Brand impersonation: Gusto"
description: |
  Impersonation of Gusto, a cloud-based payroll management company.
type: "rule"
severity: "medium"
source: |
  type.inbound
  and (
    strings.ilike(sender.display_name, '*gusto*')
    or strings.ilevenshtein(sender.display_name, 'gusto') <= 1
    or strings.ilike(sender.email.domain.domain, '*gusto*')
  )
  and any(ml.logo_detect(file.message_screenshot()).brands,
          .name == "Gusto" and .confidence in ("medium", "high")
  )
  and sender.email.domain.root_domain !~ 'gusto.com'
  
  // negate highly trusted sender domains unless they fail DMARC authentication
  and (
    (
      sender.email.domain.root_domain in $high_trust_sender_root_domains
      and not headers.auth_summary.dmarc.pass
    )
    or sender.email.domain.root_domain not in $high_trust_sender_root_domains
  )
attack_types:
  - "Credential Phishing"
tactics_and_techniques:
  - "Impersonation: Brand"
  - "Lookalike domain"
  - "Social engineering"
detection_methods:
  - "Computer Vision"
  - "Content analysis"
  - "Header analysis"
  - "Sender analysis"
id: "54025c1c-34bc-5cbf-97b8-d544806fc587"