sublimehighRule

Attachment with VBA macros from employee impersonation (unsolicited)

Attachment contains a VBA macro from a sender your organization has never sent an email to. Sender is using a display name that matches the display name of someone in your organization. VBA macros are a common phishing technique used to deploy malware.

MITRE ATT&CK

T1566.001 T1204.002 T1486 T1566.002 T1534 T1059.005 T1566 T1598

initial-accessexecution

Detection Query

type.inbound

// ensure the display name contains a space to avoid single named process accounts eg. 'billing, payment'
and strings.contains(sender.display_name, " ")
and sender.display_name in~ $org_display_names
and any(attachments,
        (
          .file_extension in~ $file_extensions_macros
          or .file_extension in~ $file_extensions_common_archives
          or (
            .file_extension is null
            and .file_type == "unknown"
            and .content_type == "application/octet-stream"
            and .size < 100000000
          )
        )
        and file.oletools(.).indicators.vba_macros.exists
)
and (
  not profile.by_sender().solicited
  or (
    profile.by_sender().any_messages_malicious_or_spam
    and not profile.by_sender().any_messages_benign
  )
)

Data Sources

Email MessagesEmail HeadersEmail Attachments

Platforms

References

https://threatpost.com/microsoft-outlook-users-targeted-by-gamaredons-new-vba-macro/156484/

Raw Content

name: "Attachment with VBA macros from employee impersonation (unsolicited)"
description: |
  Attachment contains a VBA macro from a sender your organization has never sent an email to.

  Sender is using a display name that matches the display name of someone in 
  your organization.

  VBA macros are a common phishing technique used to deploy malware.
references:
  - "https://threatpost.com/microsoft-outlook-users-targeted-by-gamaredons-new-vba-macro/156484/"
type: "rule"
severity: "high"
source: |
  type.inbound
  
  // ensure the display name contains a space to avoid single named process accounts eg. 'billing, payment'
  and strings.contains(sender.display_name, " ")
  and sender.display_name in~ $org_display_names
  and any(attachments,
          (
            .file_extension in~ $file_extensions_macros
            or .file_extension in~ $file_extensions_common_archives
            or (
              .file_extension is null
              and .file_type == "unknown"
              and .content_type == "application/octet-stream"
              and .size < 100000000
            )
          )
          and file.oletools(.).indicators.vba_macros.exists
  )
  and (
    not profile.by_sender().solicited
    or (
      profile.by_sender().any_messages_malicious_or_spam
      and not profile.by_sender().any_messages_benign
    )
  )
attack_types:
  - "Malware/Ransomware"
tactics_and_techniques:
  - "Impersonation: Employee"
  - "Macros"
  - "Social engineering"
detection_methods:
  - "Archive analysis"
  - "File analysis"
  - "Macro analysis"
  - "Sender analysis"
id: "9b262123-9010-5245-89a7-9ebd75333b2a"