Browser Helper Object: Difference between revisions

[[Image:Am{{Short addon manager.pngdescription|right|thumb|AddPlug-on Manager from Windowsin XPmodule SP2for Internet Explorer]]}}

A '''Browser Helper Object''' ('''BHO''') is a [[Library (computer science)|DLL]] [[Module (programming)|module]] designed as a [[Plug-in (computing)|plugin]] for the [[Microsoft]]'s [[Internet Explorer]] [[web browser]] to provide added functionality. BHOs were introduced in October 1997 with the release of [[Internet Explorer 4|version 4]] of Internet Explorer. Most BHOs are loaded once by each new instance of Internet Explorer. However, in the case of [[Windows Explorer]], a new instance is launched for each window.

BHOs isare still supported as of Windows 10, through [[Internet Explorer 11]], while BHOs isare not supported in their default web browser [[Microsoft Edge]].

Each time a new instance of Internet Explorer starts, it checks the [[Windows Registry]] for the key ''HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer\Browser Helper Objects''. If Internet Explorer finds this key in the registry, it looks for a [[Universally unique identifier#In COM|CLSID]] key listed below the key. The CLSID keys under Browser Helper Objects tell the browser which BHOs to load. Removing the registry key prevents the BHO from being loaded. For each CLSID that is listed below the BHO key, Internet Explorer calls CoCreateInstance to start the instance of the BHO in the same process space as the browser. If the BHO is started and implements the IObjectWithSite interface, it can control and receive events from Internet Explorer. BHOs can be created in any language that supports [[Component Object Model|COM]].<ref>Roberts Scott, ''Programming Microsoft Internet Explorer 5'', Microsoft Press, 1999, {{ISBN|0-7356-0781-8}}</ref>

The BHO [[application programming interface|API]] exposes [[hooking|hook]]s that allow the BHO to access the [[Document Object Model]] (DOM) of the current page and to control navigation. Because BHOs have unrestricted access to the Internet Explorer event model, some forms of [[malware]] (such as adware and spyware) have also been created as BHOs.<ref>{{Cite web|title=Browser ForHijack example,Objects the [[Download(BHOs)|url=https://blog.ject]]malwarebytes.com/threats/browser-hijack-objects-bhos/|access-date=2021-12-05|website=Malwarebytes malwareLabs|language=en-US}}</ref><ref>{{Cite installsjournal a|last=Park BHO|first=Beomsoo that|last2=Hong would|first2=Sungjin activate|last3=Oh upon|first3=Jaewook detecting|last4=Lee a|first4=Heejo secure|date=2005 [[HTTP]]|editor-last=Kantor connection|editor-first=Paul to|editor2-last=Muresan a|editor2-first=Gheorghe financial|editor3-last=Roberts institution,|editor3-first=Fred [[keystroke|editor4-last=Zeng logging|recordeditor4-first=Daniel theD. user's|editor5-last=Wang keystrokes]]|editor5-first=Fei-Yue (intending|editor6-last=Chen to|editor6-first=Hsinchun capture|editor7-last=Merkle passwords)|editor7-first=Ralph andC. transmit|title=Defending thea informationWeb toBrowser aAgainst websiteSpying usedwith byBrowser RussianHelper [[computerObjects crime|computer criminals]]url=https://link.springer.com/chapter/10.1007/11427995_85 |journal=Intelligence Otherand BHOsSecurity suchInformatics as|series=Lecture theNotes [[MyWayin Searchbar]]Computer trackScience users'|language=en browsing|location=Berlin, patternsHeidelberg and|publisher=Springer pass|pages=638–639 the information they record to third parties|doi=10.1007/11427995_85 |isbn=978-3-540-32063-0}}</ref>

*[https://sites.google.com/site/bhosearch/ Sites.google.com] {{Webarchive|url=https://web.archive.org/web/20141224114851/https://sites.google.com/site/bhosearch/ |date=2014-12-24 }}

*[https://web.archive.org/web/20050109091250/http://www.microsoft.com:80/windowsxp/using/web/sp2_addonmanager.mspx Control Internet Explorer Add-ons with Add-on Manager]{{snd}}an article on Microsoft.com that explains this new feature of Windows XP Service Pack 2