• Sublime Core Feed
Medium Severity

Attachment: RTF file with suspicious link

Labels

Credential Phishing
Evasion
Archive analysis
File analysis
Sender analysis
URL analysis

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 16th, 2025
Feed Source
Sublime Core Feed
Source
GitHub
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 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
MQL Rule Console
DocsLearning Labs

Playground

Test against your own EMLs or sample data.

Share

Post about this on your socials.

Get Started. Today.

Managed or self-managed. No MX changes.

Get Started