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Internet Explorer |
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Internet ExplorerInternet Explorer, abbreviated IE or MSIE, is a web browser made by Microsoft and currently available as part of Microsoft Windows. As of 2005 Internet Explorer is by far the most widely used web browser, although since 2004 it began losing usage share to other browsers such as Mozilla Firefox, Safari, and Opera. The current estimation is about 85–90% of the total usage. (see below) It is available as a built-in component in newer versions of Microsoft Windows, and as a separate free of charge product for many older versions of Microsoft Windows. It has been shipped as the default browser in all versions of Microsoft Windows since Windows 95 OSR2. However, the last major upgrade to Internet Explorer was offered for Windows XP only. Despite initial plans of delaying the release of Internet Explorer 7 until the next major version of Windows codenamed Longhorn, Microsoft has recently announced a testing version of Internet Explorer 7 will be available for Windows XP SP2 users by the summer of 2005 (see below). For a time, Microsoft also produced Internet Explorer for Mac and versions for use via the X Window System on Solaris and HP-UX, but these are no longer in active development. HistoryRelease historyInternet Explorer is derived from Spyglass, Inc.'s version of Mosaic. Microsoft licensed Spyglass's software in 1995, in an arrangement under which Spyglass would receive a quarterly fee plus a percentage of Microsoft's revenues for the software. Microsoft originally released Internet Explorer 1.0 in August 1995 with the Internet Jumpstart Kit in Microsoft Plus for Windows 95. Version 1.5 was later released that supported basic table rendering [1]. Version 2.0 was released for both Windows 95 and Windows NT in November 1995, featuring support for SSL, cookies, VRML, and Internet newsgroups [1]. Version 2.0 was also released for the Macintosh and Windows 3.1 in April 1996. Version 2.1 supported frames, but not JavaScript, Java or ActiveX [1]. Internet Explorer 3.0 was released free of charge in August 1996 by bundling it with Windows 95 OSR2. Microsoft thus made no direct revenues on IE and was liable to pay Spyglass only the minimum quarterly fee. In 1997, Spyglass threatened Microsoft with a contractual audit, in response to which Microsoft settled for US $8 million [1]. Version 3 included Internet Mail and News 1.0 and the Windows Address Book. Later, Microsoft NetMeeting and Windows Media Player were integrated into the product and thus "helper" programs became no longer as necessary as they once were. Cascading Style Sheets were also introduced with version 3 of Internet Explorer. Version 4 was released in October 1997 and was shipped with Windows 98 and was modified to integrate more closely with Microsoft Windows. It included an option to enable "Active Desktop" which displayed Web content on the desktop itself and was updated automatically as the content changed. The user could select other pages for use as Active Desktops as well. "Active Channel" technology was also introduced to automatically obtain information updates from websites. The technology was based on an XML standard known as Channel Definition Format (CDF), which predated other web syndication formats like RSS. This version was designed to work on Windows 95, Windows 98, and Windows NT, and could be downloaded from the Internet, free of charge. It supported Dynamic HTML (DHTML). Outlook Express 4.0 also came integrated into the browser and replaced the aging Microsoft Internet Mail & News product that was released with previous versions. In September 1998, Microsoft released version 5 of Internet Explorer. Bi-directional text, ruby text and direct XML/XSL support were included in this release, along with enhanced support for CSS Level 1 and 2. The actual release of Internet Explorer 5 happened in three stages. Firstly, a Developer Preview was released in June 1998 (5.0B1), and then a Public Preview was released in November 1998 (5.0B2). Then in March 1999 the final release was released (5.0). In September it was released with Windows 98. Version 5.5 was later released for Windows Me in July 2000, and included many bug fixes and security patches. [1] Version 6 was released with Windows XP in October 2001. It mainly focused on privacy and security features, as they had become customer priorities. Microsoft implemented tools that support P3P, a technology under development by the W3C. [1] In a May 7, 2003 Microsoft online chat, Brian Countryman, Internet Explorer Program Manager, declared that on Microsoft Windows, Internet Explorer will cease to be distributed separately from the operating system (IE 6 being the last standalone version) [1]; it will, however, be continued as a part of the evolution of the operating system, with IE updates coming bundled in OS upgrades. Thus, IE and Windows will be kept more in sync: it will be less likely that people will use a relatively old version of IE on a newer version of Windows, and newer versions of IE will not be usable without an OS upgrade. This also partially accounts for the slow development of Internet Explorer and Windows Longhorn: the development team that was working on Windows Longhorn and the next version of Internet Explorer needed to pause its work during the development of Service Pack 2, to add what were seen as missing features like popup blocking and security patches to Windows XP. Some argue that Microsoft should make the browser technologies specific to each revision of the operating system and forego backward compatibility. [1] Antitrust:Main article: Microsoft antitrust case In a legal case brought by the US Department of Justice and twenty U.S. states, Microsoft was accused of breaking an earlier consent decree, by bundling Internet Explorer with its operating system software. The department took issue with Microsoft's contract with OEM computer manufacturers that bound the manufacturers to include Internet Explorer with the copies of Microsoft Windows they installed on systems they shipped. Allegedly, it would not allow the manufacturer to put an icon for any other web browser on the default desktop in place of Internet Explorer. Microsoft maintained that integration of its web browser into its operating system was in the interests of consumers. Microsoft asserted in court that IE was integrated with Windows 98, and that Windows 98 could not be made to operate without it. Australian computer scientist Shane Brooks later demonstrated that Windows 98 could in fact run with IE files removed. [1] Brooks went on to develop software designed to customize Windows by removing "undesired components". [1] Microsoft has claimed that the software did not remove all components of Internet Explorer, leaving many dynamic link library files behind. On April 3 2000, Judge Jackson issued his findings of fact that Microsoft had abused its monopoly position by attempting to "dissuade Netscape from developing Navigator as a platform", that it "withheld crucial technical information", and attempted to reduce Navigator's usage share by "giving Internet Explorer away and rewarding firms that helped build its usage share" and "excluding Navigator from important distribution channels". [1] Jackson also released a remedy that suggested Microsoft should be broken up into two companies. This remedy was overturned on appeal, amidst charges that Jackson had revealed a bias against Microsoft in communication with reporters. The findings of fact that Microsoft had broken the law, however, were upheld. Seven months later, the Department of Justice agreed on a settlement agreement with Microsoft. However as of 2004, although nineteen states have agreed to the settlement, Massachusetts is still holding out. Future developmentOn February 15, 2005, Microsoft Chairman Bill Gates announced the new browser version at the RSA Conference 2005 in San Francisco. The new beta version is expected to be released in the summer of 2005, a change in direction from when it said it would release the next version of Internet Explorer only with the next version of Windows, nicknamed Longhorn. It will be available to Windows XP and later only, including Windows XP Professional x64 Edition and Windows Server 2003 SP1 [1]. The new version of Internet Explorer is intended to support tabbed browsing and defend users from phishing as well as deceptive or malicious software. However, there is no mention of further improvements in CSS and other Web standards, a heavy concern of web developers. Some see this announcement as a result of the rising usage share of other web browsers, noticeably Mozilla Firefox [1] [1] [1]. FeaturesWhile in many ways similar to competing browsers, Internet Explorer also has features that differentiate it from competitors. Distinguishing featuresThese are features found in Internet Explorer alone, which are not found in other common browsers.
The favicon (short for "favorites icon") introduced by Internet Explorer is now also supported and extended in other browsers. Web standardsDuring the browser wars of the late 1990s, modifications of Internet Explorer and Netscape were focused on the addition of non-standard features. This is in contrast to more recent browsers which have been designed with web standards in mind. Since version 5, there have been no significant changes in IE's Trident rendering engine. As a result, as of 2005, IE lags behind in support for standards. Although each version of IE has improved standards support, including the introduction of a "standards-compliant mode" in version 6, the core standards that are used to build web pages (HTML and CSS) are still implemented in an incomplete and incorrect fashion. For example, there is no support for the tag that is part of the HTML 4.01 standard, and there are bugs in the implementation of float-margins for the CSS1 standard. [1] [1] The Internet Explorer box model bug is also one of the best-known bugs in Internet Explorer's implementation of CSS. Other than PNG, Internet Explorer also does not support progressive display of progressive JPEG [1] [1]. Progressive JPEG divides the file into a series of scans. The user agent should display progressive JPEG from lower quality scans to higher quality scans during transmission of the file. The user should see a gradual improvement of the quality of the image. This was quite useful in the past since many users (especially home users) were on dial-up access where the bandwidth is very limiting. However, in Internet Explorer the image was not rendered until the completion of download. Fortunately this problem is less significant now due to the introduction of Broadband Internet access. Unlike other browsers, Internet Explorer does not obey MIME types specified in the MIME Content-Type header. For example, a document sent as text/plain containing HTML-like tags will be interpreted as a HTML document, while it was intended to be displayed as a plain text document [1]. Internet Explorer does not fully support HTTP/1.1 content negotiation, because the browser does not specify, in its requests, what MIME type and character encodings it can accept. Content negotiation is a technique whereby an HTTP server uses the browser's—ultimately, the user's—preferences for media (MIME) type, languages, character encoding, and transfer encoding (for example, compression) in order to determine the best representation of a resource to send to a user agent, when multiple representations are available. An example would be the negotiation of image format (such as SVG, PNG, or GIF), and document format (WML, XHTML, or HTML, for instance). Internet Explorer supports the Unicode standard for multilingual text, and is therefore theoretically capable of displaying any character which is present in an installed font. In practice, Internet Explorer does not automatically choose fonts for blocks of mixed Unicode text. Characters can end up displayed as blank squares or question marks. Web designers must guess which appropriate fonts may be present on users' computers, and manually specify them for every change of Unicode block. In contrast, most other browsers do this automatically. Conversely, many other web designers build websites compliant to W3C standards, and then implement workarounds or hackss to account for Internet Explorer's rendering inadequacies, or to hide advanced website features from IE. The CSS hacks are often very complicated, as they need to deal with different versions IE under different platforms (mostly Windows and Mac). The hacks utilize not just Internet Explorer-specific features, but also some rendering-engine bugs that are well known. Some of the more common hacks: One of the most popular IE hack collections is known as IE7, written by Dean Edwards. [1] It is an attempt to make Internet Explorer more compliant when it comes to web standards. In addition to the support of some CSS2 selectors, it also fixes some of the IE bugs. However, as many client-side scripts need to be loaded and run before displaying the page properly, there is a considerable amount of loading time needed for every single page. In order to render as many web pages as possible, Microsoft has designed Internet Explorer's rendering engine with strong fault-tolerance in mind. It will compensate for errors made by web designers while building web pages, by filling in missing HTML tags and ignoring structural problems. The impact of this decision is mixed. This tolerance of invalid pages does help typical end-users who have asked to view that specific page, since even terribly nonstandard pages still provide information. However, since some developers test only by seeing if IE renders a page, nonstandard pages have proliferated, making it more difficult to create tools (such as specialized search tools) that automatically process and analyze web pages. As of April 9 2005, security advisory site Secunia counts 19 security flaws unpatched (not yet fixed) for Internet Explorer 6, although some of these flaws only affect Internet Explorer when running on certain versions of Windows or when running in conjunction with certain other applications. [1] See computer security for more details about the importance of unpatched known flaws. On June 23, 2004, an attacker using compromised Microsoft IIS Web servers on major corporate sites used two previously-undiscovered security holes in IE to insert spam-sending software on an unknown number of end-user computers [1] [1] [1]. This malware became known as Download.ject and it caused users to infect their computers with a backdoor and key logger merely by viewing a web page. Infected sites included several financial sites. The United States Computer Emergency Readiness Team (US-CERT) has asserted that IE's design makes it difficult to secure. They state that "There are a number of significant vulnerabilities in technologies relating to the IE domain/zone security model, local file system (Local Machine Zone) trust, the Dynamic HTML (DHTML) document object model (in particular, proprietary DHTML features), the HTML Help system, MIME type determination, the graphical user interface (GUI), and ActiveX. … IE is integrated into Windows to such an extent that vulnerabilities in IE frequently provide an attacker significant access to the operating system." [1] In addition, some security exploits associated with Internet Explorer are made possible through normal usage patterns of users of Microsoft Windows. For example, in Windows XP, it is the default system behavior to allow normal users to log into accounts with administrator privileges for everyday computer use. In this situation, an exploit which allows a cracker to run arbitrary code effectively gives away control of the entire computer. This would be the case for any browser which ran with unrestricted privileges. Because the everyday use of root accounts for normal users is rare on other operating systems, attacks which rely upon inappropriately restricted browser processes are most often targeted at Windows-based browsers. However, many programs on Windows do not work or work poorly without administrator privileges, so what are considered normal security practices on other operating systems are sometimes impractical to perform on Windows. Many security analysts attribute IE's frequency of exploitation in part to its ubiquity, since its market dominance makes it the most obvious target. However, many others argue that this is not the full story; the Apache web server has a much larger market share than Microsoft IIS, yet Apache has had fewer (and generally less serious) security vulnerabilities than IIS. [1] Microsoft's Craig Mundie has admitted that Microsoft's products were "less secure than they could have been" because it was "designing with features in mind rather than security"—even though most people didn't use those new features. [1] As a result of its many problems, some security experts, including Bruce Schneier and David A. Wheeler, recommend that users stop using Internet Explorer for normal browsing, and switch to a different browser instead. [1] [1] Several technology columnists have suggested the same [1] [1] [1]. On July 6, 2004, US-CERT released an exploit report in which the last of seven workarounds was to use a different browser, especially when visiting untrusted sites. [1], These malware attacks mostly depend on ActiveX for their activation and propagation to other computers. Microsoft has recognized the problem with ActiveX since 1996 when Charles Fitzgerald, program manager of Microsoft's Java team said, "If you want security on the 'Net', unplug your computer. ... We never made the claim up front that ActiveX is intrinsically secure." [1] ActiveX controls, once run, have all the users' privileges instead of the limited privileges granted by competing approaches (like Java and JavaScript); ActiveX controls are also non-standard and are not portable to non-Windows platforms. As pointed out by Professor Edward Felten of Princeton University: ActiveX security relies on security zones and digital signing, which are not as reliable as other measures like sandbox security model and same origin policy [1]. It is explained in an O'Reilly book, "Malicious Mobile Code": The security problems of ActiveX were first demonstrated in February 1997 by the Chaos Computer Club (CCC), who demonstrated an ActiveX control that could communicate with an installation of Intuit's Quicken financial software on a user's hard drive to automatically transfer money from a user's account to CCC's bank account. [1] The U.S. Department of Defense (DoD) defines ActiveX as a category 1 (maximum risk) mobile code technology, and strictly limits how ActiveX can be used in DoD systems. [1] Browser Helper Objects (BHOs) are DLL components, that add functionality to Internet Explorer. They are installed by some 3rd-party software, including Morpheus and Alexa. Since BHO's have access to browser state and behavior, they may be used for malicious purposes. Furthermore, since they may be silently installed by 3rd party software and operate as a component of Internet Explorer, a user may not know that they are running within the browser. With Windows XP Service Pack 2 however, the Add-on Manager that Microsoft added to Internet Explorer lists all installed BHOs and give the user the option to enable or disable each BHO. The forth-coming Microsoft AntiSpyware, which is currently in beta, monitors BHOs in Internet Explorer on Windows 2000, XP and Server 2003, and will warn the user before a new BHO is installed. Critics have claimed that security fixes take too long to be released after discovery of the problems, and that the problems are not always completely fixed. After Microsoft released patches to close 20 holes in its general operating system in February 2003, Marc Maifrett, Chief Hacking Officer of eEye Digital Security, stated that "If it really took them that long technically to make (and test) the fix, then they have other problems. That's not a way to run a software company." [1] Maifrett was criticized by The Register for publicizing a security hole leading to the creation of the Code Red worm and stated that "had they not made such a grand public fuss over their .ida hole discovery and their SecureIIS product's ability to defeat it, it's a safe bet that Code Red would not have infected thousands of systems" [1]. Microsoft attributes the perceived delays to rigorous testing. The testing matrix for Internet Explorer demonstrates the complexity and thoroughness of corporate testing procedures. The browser is released in 26 different languages on many different Windows platforms. Therefore, it is estimated that each patch is tested on at least 237 installations. [1] Although security patches continue to be released for a range of platforms, most recent feature additions and security improvements were released for Windows XP only. Nevertheless, Internet Explorer remains the dominant web browser. Different organizations report different usage share figures, depending on their approaches and samples; web analysis company WebSideStory reports that IE has a 89.85% USA usage share (as of February 18, 2005) [1], OneStat reports that IE has an 87.28% global usage share (as of February 28, 2005) [1], and Janco Associates, Inc. reports IE has an 84.85% usage share as of January 31, 2005 [1].
Simply installing and using another browser does not prevent third party programs and core operating system components from using IE libraries. Thus, a user who does not use IE to browse the Web can still be targeted by attacks against vulnerabilities in these libraries—for instance, via Outlook Express or the Windows Help subsystem. However, removing the IE libraries will cause these programs, and other software which depends upon them, to cease functioning or even to crash the system. It is unclear what it means to "remove IE" because such a removal depends on being able to determine which files or functions on an installed Windows system are part of IE — that is, to draw a line between IE and the rest of Windows. Microsoft has held that this is not meaningful; that "IE" is no longer (as it was prior to Windows 98) a separate piece of software, but simply a brand name for the Web-browsing and HTML-displaying capacities of the Windows operating system. In this view, the result of removing IE is simply a damaged Windows system; to have a working system without IE one must replace Windows entirely. In contrast, some programmers and security writers have held that it is possible to have a useful and working Windows system with IE excised. Consultant Fred Vorck, who advocates that consumers should have the choice to remove "integrated" features of Microsoft Windows [1]; Dino Nuhagic, who is the creator of nLite — a product that allows users to remove Windows components like Internet Explorer and Windows Media Player, amongst others [1]; and Shane Brooks, who created LitePC to remove and manage Windows components [1], have all suggested removing Internet Explorer from computers in order to decrease exposure to security risks on the Internet [1]. It is possible to remove Internet Explorer from Windows 95, 98 and ME (see instructions on the Netscape website [1] and on Microsoft's website [1]), as well as from Windows 2000 and Windows XP at installation time. Microsoft claims that attempting to remove Internet Explorer from Windows may result in system instability. Microsoft's position is in contrast with other operating systems and browsers. Other operating systems typically include at least one browser—for instance, Safari and Internet Explorer for Mac in Mac OS X. However, in these systems the web browser can be removed or replaced like any other application. |
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