The GetSecurityZone method is used to determine how a
resource should be handled in terms of local security policy before performing
a file transfer or download. For example, you may want to determine whether
a resource originates from the Internet or local intranet before deciding
whether to attach zone metadata, prompt the user, or apply additional
security restrictions. It can also be used to implement policy-based rules
for accepting or rejecting downloads based on their origin.
If the resource is specified using a file:// URL that
refers to a file on a network share (e.g.: file://server/share/file.txt),
the method will attempt to access that file across the network.
This may cause the application to block while Windows resolves the
hostname and establishes a connection to the shared volume. If the
network share is unavailable or slow to respond, the method may
block until the connection succeeds or the attempt times out.
If this method returns httpZoneNone, this indicates
either the resource type is not supported or there was an internal
failure when the Internet Security Manager attempted to map the resource
URL to a security zone. In most default configurations, this method
will return the zone httpZoneInternet for valid URLs unless the host
has been explicitly added to the Intranet Zone or Trusted Sites
list on the local system.
Security zones are used with Mark of the Web (MOTW) metadata which
indicates if a file originated from an external source, such as the
Internet or an untrusted network. When a file is downloaded using
a web browser or other applications, it may add a Zone.Identifier
alternate data stream to the file. This stream contains information
such as ZoneId=3, which corresponds to the Internet Zone.
Your application can use the GetFileZone method to
retrieve this information, which allows you to determine whether a
file was downloaded from an external source and what zone Windows has
associated with it. This metadata affects how files are handled by
Windows security components such as Microsoft Defender, SmartScreen,
Office Protected View, and script execution policies in Windows Explorer.
If the file has no metadata, it is generally treated as coming from
the Local Machine Zone (zone 0). If your application sets or clears
this metadata using the SetFileZone method, it can influence
how other applications interpret the file's trust level.
It is important to note that this method is used to determine
what security zone would be appropriate for a given resource, and it
only performs syntactic checks and classification of the URL using the
IInternetSecurityManager COM interface. The security zone this
method returns is based on the current system and user policy, using
zone assignments stored in the registry. Typically this information is
managed using Windows settings or Internet options in the control
panel. This method does not read the zone identifier metadata which
has been assigned to a file.
For more detailed information about the zone identifiers, refer to
the ZoneId property.