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High Severity

Attachment: HTML smuggling with embedded base64-encoded ISO

Labels

Credential Phishing
Malware/Ransomware
Evasion
HTML smuggling
ISO
Archive analysis
Content analysis
File analysis
HTML analysis
Sender analysis

Description

HTML attachment contains a base-64 encoded ISO. This is a known TTP for multiple threat actors.

References

Sublime Security
Created Aug 17th, 2023 • Last updated Aug 21st, 2023
Feed Source
Sublime Core Feed
Source
GitHub
type.inbound
and any(attachments,
        (
          .file_extension in~ ("html", "htm")
          or .file_extension in~ $file_extensions_common_archives
          or .file_type == "html"
        )
        and any(file.explode(.),
                any(.scan.strings.strings,
                    strings.ilike(.,
                                  // Base64 encoded ISOs
                                  "*SVNPIDk2NjAvSEZT*",
                                  "*MTk5MyBFLllPVU5HREFMRQ*",
                                  // Reversed base64 encoded ISOs
                                  "*TZESvAjN2kDIPNVS*",
                                  "*QRMFERH5UVPllLFByM5kTM*"
                    )
                )
        )
)
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