Mark of the Web

Common card · No. 277139

The Mark of the Web (MoTW) is a metadata identifier used by Microsoft Windows to mark files downloaded from the Internet as potentially unsafe. Although its name specifically references the Web, it is also sometimes added to files from other sources perceived to be of high risk, including files copied from NTFS-formatted external drives that were themselves downloaded from the web at some earlier point. It is implemented using the alternate data stream (ADS) feature of Microsoft's default NTFS filesystem. Due to its reliance on features exclusive to NTFS, transferring the file to or from a partition with an alternative filesystem, such as FAT32 or Ext4, will strip the file of its ADSs and thus the mark. These alternate streams are intended to be transparent (i.e. hidden from most users) and are not shown to or made editable by users through any GUI built into Windows by default. A second type of MotW can arise when saving a webpage as an HTML document, as most browsers will insert an HTML...

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