• Sublime Core Feed
Medium Severity

Attachment: RTF file with suspicious link

Description

This rule detects RTF attachments directly attached or within an archive, containing an external link to a suspicious low reputation domain.

References

No references.

Sublime Security
Created Aug 2nd, 2024 • Last updated Jul 23rd, 2025
Source
type.inbound
and any(attachments,
        (
          .file_extension in~ $file_extensions_common_archives
          or .file_type == "rtf"
        )
        and any(file.explode(.),
                .flavors.mime == 'text/rtf'
                and any(.scan.url.urls,
                        .domain.valid
                        and .domain.subdomain is not null
                        and not (
                          strings.ends_with(.url, "jpeg")
                          or strings.ends_with(.url, "png")
                        )
                        and (
                          (
                            .domain.root_domain not in $tranco_1m
                            and .domain.root_domain not in $umbrella_1m
                          )
                          or (
                            .domain.root_domain in $free_file_hosts
                            or .domain.root_domain in $free_file_hosts
                            or .domain.root_domain in $free_subdomain_hosts
                            or .domain.root_domain in $url_shorteners
                            or .domain.root_domain in $social_landing_hosts
                          )
                          // or the url contains the recipient email and the root_domain is not in tranco
                          or (
                            any(recipients.to,
                                strings.icontains(..url, .email.email)
                            )
                            and (
                              .domain.root_domain not in $tranco_1m
                              and .domain.root_domain not in $umbrella_1m
                            )
                          )
                        )
                )
        )
)
and not profile.by_sender().solicited
and not profile.by_sender().any_messages_benign
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