• Sublime Core Feed
High Severity

Attachment: Archive contains DLL-loading macro

Labels

Malware/Ransomware
Exploit
LNK
Macros
Scripting
Archive analysis
File analysis
Macro analysis
YARA

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 Dec 28th, 2023
Feed Source
Sublime Core Feed
Source
GitHub
type.inbound
and any(attachments,
        (
          .file_extension in~ $file_extensions_common_archives
          or .file_type == "rar"
        )
        and (
          (
            any(file.explode(.),
                .scan.zip.encrypted == false
                // zip contains a dll file
                and any(.scan.zip.all_paths, strings.icontains(., "dll"))
            )
            and any(file.explode(.),
                    // macro references a dll file
                    any(.flavors.yara, strings.like(., "vb_file"))
                    and any(.scan.strings.strings, strings.icontains(., "dll"))
            )
          )
          or any(file.explode(.), // fallback for encrypted zips
                 .scan.zip.encrypted == true
                 and any(.scan.zip.all_paths,
                         any($file_extensions_macros, strings.icontains(.., .))
                 )
                 // zip contains a dll file
                 and any(.scan.zip.all_paths, strings.icontains(., "dll"))
          )
          or (
            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"))
          )
        )
)
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