HTML Application: Difference between revisions

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{{Short description|Microsoft Windows program}}

:''{{This article refers to |Microsoft's proprietary HTA implementation. For |information regarding the [[HTML5]] Cache Manifest, also referred to as offline HTML applications, please see [[|Cache manifest in HTML5]].''}}

{{ Infobox file format

| name = HTML Application (HTA)

| icon =

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| screenshot =

| caption =

| extension = <tt>{{mono|.hta</tt>}}

| mime = application/hta

| typecode =

| uniform type =

| magic = <code>{{mono|%hta</code>}}

| owner = [[Microsoft]]

| released = <!-- {{Start date|YYYY|mm|dd|df=yes}} -->

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| standard =

| free =

| url = {{URL|1=https://msdnlearn.microsoft.com/en-us/libraryprevious-versions/ms536471(VSv=vs.85).aspx?redirectedfrom=MSDN}}

}}

An '''HTML Application''' ('''HTA''') is a [[Microsoft Windows]] program whose source code consists of [[HTML]], [[Dynamic HTML]], and one or more scripting languages supported by [[Internet Explorer]], such as [[VBScript]] or [[JScript]]. The HTML is used to generate the user interface, and the scripting language is used for the program logic. An HTA executes without the constraints of the internetweb browser security model; in fact, it executes as a "fully trusted" application.

The usual file extension of an HTA is <code>.hta</code>.

The ability to execute HTAs was introduced to Microsoft Windows in 1999, along with the release of [[Microsoft Internet Explorer 5]].<ref>[http://support.microsoft.com/kb/200874 ''Article ID:200874 in Microsoft Support''], in Microsoft Support Knowledge Base</ref> On December 9, 2003, this technology was [[patent]]ed.<ref>[http{{Cite patent|number=US6662341B1|title=Method and apparatus for writing a windows application in HTML|gdate=2003-12-09|invent1=Cooper|invent2=Kohnfelder|invent3=Chavez|inventor1-first=Phillip R.|inventor2-first=Loren M.|inventor3-first=Roderick A.|url=https://newspatents.cnetgoogle.com/2100patent/US6662341B1/en?oq=PN/6,662,341}}</ref><ref>{{Cite web |last=Festa |first=Paul |date=2003-1012_312-5119072.html10 |title=Microsoft wins HTML application patent |url=http://www.cnet.com/news/microsoft-wins-html-application-patent/ |url-status=dead |archive-url=https://web.archive.org/web/20160310170211/http://www.cnet.com/news/microsoft-wins-html-application-patent/ |archive-date=2016-03-10 |access-date=2016-01-10 |website=[[CNET]]}}</ref>

== Uses ==

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===Execution===

[[File:HTA-Hello World exampleRectifiedWikipediaHTAWindow.png|alt=|thumb|300x300px346x346px|ScreenshotOne screenshot of anone example window that is produced by <code>mshta.exe</code>]]

[[File:HTA-Hello World example.png|thumb|300x300px|Screenshot of an example window produced by <code>mshta.exe</code>]]

An HTA is executed using the program <code>mshta.exe</code>, or, alternatively, double-clicking on the file. This program is typically installed along with Internet Explorer. <code>mshta.exe</code> executes the HTA by instantiating the Internet Explorer rendering engine (mshtml) as well as any required language engines (such as vbscript.dll).

An HTA is treated like any executable file with extension [[EXE|<code>.exe</code>]]. When executed via mshta.exe (or if the file icon is double-clicked), it runs immediately. When executed remotely via the browser, the user is asked once, before the HTA is downloaded, whether or not to save or run the application; if saved, it can simply be run on demand after that.<ref name=msintro/>

By default, HTAs are rendered as per "standards-mode content in IE7 Standards mode and quirks mode content in IE5 (Quirks) mode", but this can be altered using <code>X-UA-Compatible</code> headers.<ref name=msintro>{{cite web |url=https://msdn.microsoft.com/en-us/library/ms536496%28v=vs.85%29.aspx#Compatibility |title=Introduction to HTML Applications (HTAs).|website=MicrosftMicrosoft MSDN|date=May 2011 |author= |accessdateaccess-date= 24 June 2016}} Sections include Why Use HTAs, Creating an HTA, HTA-Specific Functionality, Security, Compatibility, Deployment</ref>

TheHTAs HTAare enginedependent on the Trident (mshta.exeMSHTML) isbrowser dependentengine, onused by [[Internet Explorer]]., Startingbut fromare [[Windowsnot Vista]],dependent on the Internet Explorer application itself. If a user can [[Removal of Internet Explorer|removeremoves Internet Explorer]] from Windows, whichvia willthe causeControl Panel, the HTAMSHTML engine remains and HTAs continue to stopwork. HTAs continue to work in Windows 11 as workingwell.

HTAs are fully supported running in modes equivalent to Internet Explorer from versions 5 to 9. Further versions, such as 10 and 11, still support HTAs though with some minor features turned off.{{fact|date=May 2015}}

===Security considerations===

{{main|Browser security}}

When a regular HTML file is executed, the execution is confined to the security model of the [[web browser]],. thatThis is,means it is confined to communicating with the server, manipulating the page's [[object model]] (usually to validate forms and/or create interesting visual effects) and reading or writing [[HTTP cookie|cookies]].

On the other hand, an HTA runs as a fully trusted application and therefore has more privileges than a normal HTML file; for example, an HTA can create, edit and remove files and [[Windows Registry|registry]] entries. Although HTAs run in this 'trusted' environment, querying [[Active Directory]] can be subject to Internet Explorer Zone logic and associated error messages.

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==Vulnerabilities==

HTA have been used to deliver malware.<ref>{{Cite web|url=https://www.vmray.com/cyber-security-blog/spora-ransomware-dropper-hta-infect-system/|title=Spora Ransomware Dropper Uses HTA to Infect System|date=2017-01-17|website=VMRay|language=en-US|access-date=2018-12-22}}</ref><ref>{{Cite web|url=https://blog.netwrix.com/2017/06/01/nine-scariest-ransomware-viruses/|title=8 Scariest Ransomware Viruses|language=en-US|access-date=2018-12-22}}</ref> One particular HTA, named ''[[4chan]].hta'' (detected by antiviruses as JS/Chafpin.gen), was widely distributed by the users of the imageboard as a [[steganographic]] image in which the user were instructed to download the picture as an HTA file, which when executed, would cause the computer to automatically spam the website (evading 4chan's [[CAPTCHA]] in the process) with alternate variants of itself; it was reported that such attacks were previously delivered in which the user was prompted to save it as a [[JavaScript|.js]] file.<ref>{{cite web |last1=Constantin |first1=Lucian |title=4chan Flood Script Is Back with New Social Engineering Trick |url=https://news.softpedia.com/news/4chan-Flood-Script-Is-Back-with-New-Social-Engineering-Trick-151603.shtml |website=Softpedia |access-date=2021-11-09 |date=2010-08-10}}</ref>

==Example==

This is an example of [["Hello, World!" program|Hello World]] as an HTML Application.

<sourcesyntaxhighlight lang="html4stricthtml">

<HTML>

<HEAD>

<HTA:APPLICATION ID="HelloExample"

BORDER="thickbold"

BORDERSTYLE="complex"/>

<TITLE>HTA - Hello World</TITLE>

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</BODY>

</HTML>

</syntaxhighlight>

</source>

== See also ==

*[[Adobe AIR]]

*[[Active Scripting]]

*[[Apache Cordova]]

*[[Chromium Embedded Framework]]

*[[Electron (software framework)]]

*[[Firefox OS]]

*[[React Native]]

*[[XAML Browser Applications]] (XBAPs)

*[[XUL]] and [[XULRunner]] - a language and environment for Mozilla cross-platform applications that resembles the mechanism of HTML Applications.

*[[ApacheWindows CordovaScript Host]]

==References==

{{reflistReflist}}

==External links==

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{{Internet Explorer}}

[[Category:Widget enginesHTML|Application]]

[[Category:User interface markup languages]]

[[Category:Internet Explorer]]

[[Category:HTMLUser interface markup languages]]

[[Category:Widget engines]]