sublimehighRule

Attachment: Macro with suspected use of COM ShellBrowserWindow object for process creation

Macro references the ShellBrowserWindow COM object which can be used to spawn new processes from Explorer.exe rather than as a child process of the Office application. This can be useful for a threat actor attempting to evade security controls.

MITRE ATT&CK

T1566.001 T1204.002 T1486 T1059.005 T1059

execution

Detection Query

type.inbound
and any(attachments,
        (
          .file_extension in~ $file_extensions_macros
          or (
            .file_extension is null
            and .file_type == "unknown"
            and .content_type == "application/octet-stream"
            and .size < 100000000
          )
        )
        and any(file.explode(.),
                any(.scan.strings.strings,
                    strings.ilike(.,
                                  "*new:C08AFD90-F2A1-11D1-8455-00A0C91F3880*"
                    )
                )
        )
)

Author

ajpc500

Data Sources

Email MessagesEmail HeadersEmail Attachments

Platforms

References

Raw Content

name: "Attachment: Macro with suspected use of COM ShellBrowserWindow object for process creation"
description: |
  Macro references the ShellBrowserWindow COM object which can be used to spawn new processes from Explorer.exe rather than as a child process of the Office application. This can be useful for a threat actor attempting to evade security controls.
references:
  - "https://blog.f-secure.com/dechaining-macros-and-evading-edr/"
  - "https://delivr.to/payloads?id=0db5ac46-b59d-4bec-8252-59a40a0d9dec"
type: "rule"
authors:
  - twitter: "ajpc500"
severity: "high"
source: |
  type.inbound
  and any(attachments,
          (
            .file_extension in~ $file_extensions_macros
            or (
              .file_extension is null
              and .file_type == "unknown"
              and .content_type == "application/octet-stream"
              and .size < 100000000
            )
          )
          and any(file.explode(.),
                  any(.scan.strings.strings,
                      strings.ilike(.,
                                    "*new:C08AFD90-F2A1-11D1-8455-00A0C91F3880*"
                      )
                  )
          )
  )
attack_types:
  - "Malware/Ransomware"
tactics_and_techniques:
  - "Macros"
  - "Scripting"
detection_methods:
  - "Content analysis"
  - "File analysis"
  - "Macro analysis"
id: "527fc7f0-2750-57e2-bf2f-fbfea88b1004"