Detection rules › Sublime MQL

Service abuse: Square marketing with suspicious QR code

Severity
high
Type
rule
Source
github.com/sublime-security/sublime-rules

Detects messages from Square's marketing domain containing QR codes that redirect to self-service creation platforms, file sharing services, or image hosting services.

Threat classification

Sublime's own taxonomy (not MITRE ATT&CK).

CategoryValues
Attack typesCredential Phishing
Tactics and techniquesQR code, Free file host

Event coverage

Message attribute
sender.email
type

Rule body MQL

type.inbound
and sender.email.domain.domain == "squaremktg.com"
and beta.scan_qr(file.message_screenshot()).found
//
// This rule makes use of a beta feature and is subject to change without notice
// using the beta feature in custom rules is not suggested until it has been formally released
//
and any(filter(beta.scan_qr(file.message_screenshot()).items,
               // ignore square's own free website hosting service
               .url.domain.root_domain != "square.site"
        ),
        (
          .url.domain.root_domain in $self_service_creation_platform_domains
          or .url.domain.domain in $self_service_creation_platform_domains
        )
        or (
          .url.domain.root_domain in $free_file_hosts
          or .url.domain.domain in $free_file_hosts
        )
)

Detection logic

Scope: inbound message.

Detects messages from Square's marketing domain containing QR codes that redirect to self-service creation platforms, file sharing services, or image hosting services.

  1. inbound message
  2. sender.email.domain.domain is 'squaremktg.com'
  3. beta.scan_qr(file.message_screenshot()).found
  4. any of filter(...) where any holds:
    • any of:
      • .url.domain.root_domain in $self_service_creation_platform_domains
      • .url.domain.domain in $self_service_creation_platform_domains
    • any of:
      • .url.domain.root_domain in $free_file_hosts
      • .url.domain.domain in $free_file_hosts

Inspects: sender.email.domain.domain, type.inbound. Sensors: beta.scan_qr, file.message_screenshot. Reference lists: $free_file_hosts, $self_service_creation_platform_domains.

Indicators matched (1)

FieldMatchValue
sender.email.domain.domainequalssquaremktg.com