Detection rules › Sublime MQL

Stripe invoice abuse

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

A fraudulent invoice/receipt found in the body of the message sent by exploiting Stripe's invoicing service. Callback Phishing is an attempt by an attacker to solicit the victim (recipient) to call a phone number. The resulting interaction could lead to a multitude of attacks ranging from Financial theft, Remote Access Trojan (RAT) Installation or Ransomware Deployment.

Threat classification

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

CategoryValues
Attack typesBEC/Fraud, Callback Phishing
Tactics and techniquesPDF

Event coverage

Rule body MQL

type.inbound
and length(attachments) == 2
and sender.email.domain.root_domain == "stripe.com"
and headers.auth_summary.dmarc.pass
and any(attachments,
        .file_extension == "pdf"
        and any(file.explode(.),
                4 of (
                  strings.ilike(.scan.ocr.raw, "*Btc Purchase*"),
                  strings.ilike(.scan.ocr.raw, "*suspicious activity*"),
                  strings.ilike(.scan.ocr.raw,
                                "*get in touch with us straight once*"
                  ),
                  strings.ilike(.scan.ocr.raw, "*your phone number*"),
                  strings.ilike(.scan.ocr.raw, "*due deducted*"),
                  strings.ilike(.scan.ocr.raw,
                                "*merchant security service center*"
                  ),
                )
        )
)

Detection logic

Scope: inbound message.

A fraudulent invoice/receipt found in the body of the message sent by exploiting Stripe's invoicing service. Callback Phishing is an attempt by an attacker to solicit the victim (recipient) to call a phone number. The resulting interaction could lead to a multitude of attacks ranging from Financial theft, Remote Access Trojan (RAT) Installation or Ransomware Deployment.

  1. inbound message
  2. length(attachments) is 2
  3. sender.email.domain.root_domain is 'stripe.com'
  4. headers.auth_summary.dmarc.pass
  5. any of attachments where all hold:
    • .file_extension is 'pdf'
    • any of file.explode(.) where:
      • at least 4 of 6: .scan.ocr.raw matches any of 6 patterns
        • *Btc Purchase*
        • *suspicious activity*
        • *get in touch with us straight once*
        • *your phone number*
        • *due deducted*
        • *merchant security service center*

Inspects: attachments[].file_extension, headers.auth_summary.dmarc.pass, sender.email.domain.root_domain, type.inbound. Sensors: file.explode, strings.ilike.

Indicators matched (8)

FieldMatchValue
sender.email.domain.root_domainequalsstripe.com
attachments[].file_extensionequalspdf
strings.ilikesubstring*Btc Purchase*
strings.ilikesubstring*suspicious activity*
strings.ilikesubstring*get in touch with us straight once*
strings.ilikesubstring*your phone number*
strings.ilikesubstring*due deducted*
strings.ilikesubstring*merchant security service center*