• Sublime Core Feed
High Severity

Attachment: Calendar invite with suspicious link leading to an open redirect

Labels

Spam
Free email provider
Free file host
Free subdomain host
Open redirect
Content analysis
URL analysis

Description

Calendar invite contains a link to either a free file host or free subdomain host, and the resulting webpage contains another link to an open redirect.

References

No references.

Sublime Security
Created Mar 26th, 2024 • Last updated Apr 25th, 2024
Feed Source
Sublime Core Feed
Source
GitHub
type.inbound
and any(attachments,
        (
          .file_extension == "ics"
          or .content_type in ("application/ics", "text/calendar")
        )
        and any(file.explode(.),
                any(.scan.url.urls,
                    (
                      .domain.domain in $free_file_hosts
                      or (
                        .domain.root_domain in $free_subdomain_hosts
                        and .domain.subdomain is not null
                        and not (
                          strings.ends_with(.url, "jpeg")
                          or strings.ends_with(.url, "png")
                        )
                        and .domain.subdomain != "www"
                      )
                    )
                    and any(ml.link_analysis(.).final_dom.links,
                            any(.href_url.rewrite.encoders,
                                strings.icontains(., "open_redirect")
                            )
                    )
                )
        )
)
// negate highly trusted sender domains unless they fail DMARC authentication
and (
  (
    sender.email.domain.root_domain in $high_trust_sender_root_domains
    and (
      any(distinct(headers.hops, .authentication_results.dmarc is not null),
          strings.ilike(.authentication_results.dmarc, "*fail")
      )
    )
  )
  or sender.email.domain.root_domain not in $high_trust_sender_root_domains
)
and (
  not profile.by_sender().solicited
  or (
    profile.by_sender().any_messages_malicious_or_spam
    and not profile.by_sender().any_false_positives
  )
)
and not profile.by_sender().any_false_positives
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