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High Severity

Attachment: Archive containing HTML file with file scheme link

Labels

Credential Phishing
Evasion
Exploit
HTML smuggling
Social engineering
Archive analysis
File analysis
HTML analysis

Description

Attached archive contains an HTLM file with a file:// link, likely pointing to an SMB server. This technique can be used to steal NTLM hashes of users who open the HTML file. Known technique of TA577.

References

Sublime Security
Created Mar 7th, 2024 • Last updated Mar 7th, 2024
Feed Source
Sublime Core Feed
Source
GitHub
type.inbound
and any(attachments,
        .file_extension in $file_extensions_common_archives
        and any(file.explode(.),
                (
                  .file_extension in~ ("html", "htm", "shtml", "dhtml")
                  or .flavors.mime == "text/html"
                  or any(.flavors.yara, . == "html_file")
                )
                and any(.scan.url.urls, .scheme == "file")
        )
)
and (
  not profile.by_sender().solicited
  or (
    profile.by_sender().any_messages_malicious_or_spam
    and not profile.by_sender().any_false_positives
  )
)
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