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High Severity

Attachment: Archive contains DLL-loading macro

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Description

An attacker could send a trusted and signed document that references an untrusted DLL file, which will be loaded by the signed document.

References

Sublime Security
Created Aug 17th, 2023 • Last updated Sep 11th, 2023
Feed Source
Sublime Core Feed
Source
GitHub
type.inbound
and any(attachments,
        (
          .file_extension == "zip"
          and (
            any(file.explode(.),
                .scan.zip.encrypted == false
                // zip contains a dll file
                and any(.scan.zip.all_paths, strings.icontains(., "dll"))
            )
            and any(file.explode(.),
                    // macro references a dll file
                    any(.flavors.yara, strings.like(., "vb_file"))
                    and any(.scan.strings.strings, strings.icontains(., "dll"))
            )
          )
        )
        or any(file.explode(.), // fallback for encrypted zips
               .scan.zip.encrypted == true
               and any(.scan.zip.all_paths, any($file_extensions_macros, strings.icontains(.., .)))
               // zip contains a dll file
               and any(.scan.zip.all_paths, strings.icontains(., "dll"))
        )
        or (
          .file_extension in~ $file_extensions_common_archives
          and any(file.explode(.),
                  any(.flavors.yara, strings.like(., "vb_file"))
                  and any(.scan.strings.strings, strings.ilike(., "*Lib*.dll*"))
          )
          and any(file.explode(.), strings.ilike(.file_extension, "dll"))
        )
)

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