Detection rules › Sublime MQL

Attachment: Canva PDF with susupicious author metadata

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

Detects inbound messages containing PDF attachments that were created using Canva but have author metadata containing '@proton.me', indicating potential service abuse where legitimate design tools are being misused in conjunction with privacy-focused email services.

Threat classification

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

CategoryValues
Attack typesBEC/Fraud, Credential Phishing
Tactics and techniquesFree email provider, PDF

Event coverage

Rule body MQL

type.inbound
and any(filter(attachments, .file_type == "pdf"),
        strings.icontains(beta.parse_exif(.).author, '@proton.me')
        and beta.parse_exif(.).producer == 'Canva'
)

Detection logic

Scope: inbound message.

Detects inbound messages containing PDF attachments that were created using Canva but have author metadata containing '@proton.me', indicating potential service abuse where legitimate design tools are being misused in conjunction with privacy-focused email services.

  1. inbound message
  2. any of filter(attachments) where all hold:
    • beta.parse_exif(.).author contains '@proton.me'
    • beta.parse_exif(.).producer is 'Canva'

Inspects: attachments[].file_type, type.inbound. Sensors: beta.parse_exif, strings.icontains.

Indicators matched (2)

FieldMatchValue
attachments[].file_typeequalspdf
strings.icontainssubstring@proton.me