sublimemediumRule

Invoicera infrastructure abuse

This rule is tailored to flag infrastructural abuse involving Invoicera, a SaaS-based invoicing and billing platform, which has been identified as a tool in widespread spam and credential phishing campaigns.

MITRE ATT&CK

T1566 T1566.001 T1566.002 T1598

initial-access

Detection Query

type.inbound
and sender.email.domain.root_domain == "invoicera.com"
// suspicious recipient pattern
and (
  length(recipients.to) == 0
  or any(recipients.to, .email.domain.valid == false)
  or length(recipients.bcc) > 0
)
// suspicious link
and (
  any(body.links,
      .href_url.domain.root_domain in $free_file_hosts
      or .href_url.domain.domain in $free_file_hosts
  )
  or any(body.links,
         .href_url.domain.root_domain in $free_subdomain_hosts
         and .href_url.domain.subdomain is not null
         and .href_url.domain.subdomain != "www"
  )
)
// mismatched reply-to
and (
  headers.return_path.email is not null
  and headers.return_path.email != sender.email.email
)

Data Sources

Email MessagesEmail HeadersEmail Attachments

Platforms

Raw Content

name: "Invoicera infrastructure abuse"
description: "This rule is tailored to flag infrastructural abuse involving Invoicera, a SaaS-based invoicing and billing platform, which has been identified as a tool in widespread spam and credential phishing campaigns."
type: "rule"
severity: "medium"
source: |
  type.inbound
  and sender.email.domain.root_domain == "invoicera.com"
  // suspicious recipient pattern
  and (
    length(recipients.to) == 0
    or any(recipients.to, .email.domain.valid == false)
    or length(recipients.bcc) > 0
  )
  // suspicious link
  and (
    any(body.links,
        .href_url.domain.root_domain in $free_file_hosts
        or .href_url.domain.domain in $free_file_hosts
    )
    or any(body.links,
           .href_url.domain.root_domain in $free_subdomain_hosts
           and .href_url.domain.subdomain is not null
           and .href_url.domain.subdomain != "www"
    )
  )
  // mismatched reply-to
  and (
    headers.return_path.email is not null
    and headers.return_path.email != sender.email.email
  )

attack_types:
  - "Credential Phishing"
  - "Spam"
tactics_and_techniques:
  - "Free file host"
  - "Free subdomain host"
  - "Image as content"
  - "Social engineering"
detection_methods:
  - "Content analysis"
  - "Header analysis"
  - "Sender analysis"
id: "1e56f310-750b-5c26-84eb-63e78f20a6bd"