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Medium Severity

Attachment: Link file with UNC path

Description

Attached link file contains a UNC path. This can be used to relay NTLM password hashes; Windows will attempt to authenticate against the path even without the file being opened.

Sublime Security
Created Aug 17th, 2023 • Last updated Jan 12th, 2026
Source
type.inbound
and any(attachments,
        .file_extension in ("lnk", "url")
        and any(file.explode(.),
                any(.scan.strings.strings,
                    regex.icontains(.,
                                    '\\\\([a-zA-Z0-9_:%.$-]+)\\([a-zA-Z0-9_:%.$-]+)'
                    )
                ) // normal UNC paths
                or any(.scan.strings.strings,
                       regex.icontains(.,
                                       '%5C%5C([a-zA-Z0-9_:%.$-]+)%5C([a-zA-Z0-9_:%.$-]+)'
                       )
                ) // percent-encoded UNC paths
        )
)
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