What is entity reference?
An entity reference is a group of characters used in text as a substitute for a single specific character that is also a markup delimiter in XML. Using the entity reference prevents a literal character from being mistaken for a markup delimiter For example, if an attribute must contain a left angle bracket (<), you can substitute the entity ...
What are the basics of XML?
XML and HTML were designed with different goals:
- XML is designed to carry data emphasizing on what type of data it is.
- HTML is designed to display data emphasizing on how data looks
- XML tags are not predefined like HTML tags.
- HTML is a markup language whereas XML provides a framework for defining markup languages.
What is the difference between XML and XSD?
Summary:
- XSD is based and written on XML.
- XSD defines elements and structures that can appear in the document, while XML does not.
- XSD ensures that the data is properly interpreted, while XML does not.
- An XSD document is validated as XML, but the opposite may not always be true.
- XSD is better at catching errors than XML.
What are XML eXternal Entity (XXE) attacks?
XXE or XML External Entity attack is a web application vulnerability that affects a website which parses unsafe XML that is driven by the user. XXE attack when performed successfully can disclose local files in the file system of the website.
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What are character entities in XML?
Character entities are a method of including arbitrary characters in XML documents by referencing their UNICODE number rather than writing them directly. CSS has a similar mechanism to include special characters.
What is XML DOM object is entity reference?
The EntityReference objects are the general entity references which are inserted into the XML document providing scope to replace the text. The EntityReference Object does not work for the pre-defined entities since they are considered to be expanded by the HTML or the XML processor.
What is &# in XML?
The number in each sequence is the ASCII value of that character....Using Special Characters in XML.Symbol (name)Escape Sequence& (ampersand)&' (apostrophe or single quote)'" (double-quote)"2 more rows
How many types of entity are there in XML?
In general, we have three types of entities: internal entities, external entities, and parameter entities.
What is the purpose of XML DOM?
The XML Document Object Model (DOM) class is an in-memory representation of an XML document. The DOM allows you to programmatically read, manipulate, and modify an XML document. The XmlReader class also reads XML; however, it provides non-cached, forward-only, read-only access.
What is mean by entity reference in Java?
An entity reference is a reference to an entity. Entities are used to store data such as a node, user, etc.
What does > mean in XML?
the greater-than sign> stands for the greater-than sign: > ≤ stands for the less-than or equals sign: ≤ ≥ stands for the greater-than or equals sign: ≥
What is XML format example?
xml. It is formatted with tags like HTML tags and other XML-based file types include EDS, FDX, and DAE files. An XML file acts as a database to store the data. The most commonly used example of an XML-based file is RSS Feed.
Do you not use entity references?
Google's HTML/CSS Style Guide advises against using entity references: Do not use entity references. There is no need to use entity references like — , ” , or ☺ , assuming the same encoding (UTF-8) is used for files and editors as well as among teams.
How do you declare an entity?
An entity declaration is created by using the syntax in a document type definition (DTD) or XML schema. Secondly, the name defined in the entity declaration is subsequently used in the XML. When used in the XML, it is called an entity reference.
What is entity and element in XML?
As we said previously, an XML DTD is a collection of XML entity and element declarations and comments. Entities are name/value pairs that make the DTD easier to read and understand, while elements are the actual markup tags defined by the DTD, like HTML's
or
tags.
What is internal and external entity in XML?
Internal Entities: An internal entity (as we saw in above example) is one that is defined locally. Basic purpose of an internal entity is to avoid duplications by using same entity reference multiple times. External Entities: The difference with Internal Entity is; the external entity is defined in an separate file.
Is the XML DOM object is entity?
Entity interface represents a known entity, either parsed or unparsed, in an XML document. The nodeName attribute that is inherited from Node contains the name of the entity. An Entity object does not have any parent node, and all its successor nodes are read-only.
Which DOM node type may not have the entity reference node type as one of its child nodes?
A CDATASection node cannot have any child nodes. The CDATASection node can appear as the child of the DocumentFragment, EntityReference, and Element nodes. The node represents a reference to an entity in the XML document (its nodeTypeString property is "entityreference").
Which statement is true about XML Mcq?
All the statements are true. All XML documents must have a DTD. All XML elements must be lowercase.
Is it easier to process XML than HTML?
Yes, XML is easier to process XML than HTML. XML is extensible because it is not a fixed format like HTML. It is easy to write programs which process XML document.
What is the semicolon on the end of an XML document?
A general entity is referenced within an xml document must be surrounded by an ampersand (&) on one end and the semicolon (;) on the other (&myEntity;).
Why is document entity important?
The reason the document entity is important is that, at the end of the day, it's the only thing the xml specifications requires an xml parser to read. Document entities are defined as xml documents are parsed before it has been used. Previous: XML declarations.
What is XML in HTML?
Like html, xml also has entities and widely used to reap several advantages while creating an xml document. By specification, XML documents consist of a set of storage units. These storage units are called Entities. Entities act as a replacement mechanism.
What is entity in XML?
To explain in another note, we can say that Entities can be used as a kind of shortcut that allows you to embed blocks of text or even entire documents and files into an XML document. This makes updating documents across networks very easy.
What are the three types of entities?
In general, we have three types of entities: internal entities, external entities, and parameter entities .
Why repeat frequently used names?
Repeating frequently used names in a way that guarantees consistency in spelling and use. Providing for easier updates. By using entities in your markup for items you know will be changed later-such as weather reports or software version changes-you greatly improve dynamic document automation.
What is an entity in Microsoft Word?
Entities act as a replacement mechanism. A similar kind of example of using entities is, creating and attaching mail-merge to Microsoft Word documents. We create a database of names and address and attach them to an MS Word document.
Why are character entities introduced?
They are introduced to avoid the ambiguity while using some symbols. For example, an ambiguity is observed when less than ( < ) or greater than ( > ) symbol is used with the angle tag ( <> ). Character entities are basically used to delimit tags in XML. Following is a list of pre-defined character entities from XML specification. These can be used to express characters without ambiguity.
What is character entity?
Character entities are basically used to delimit tags in XML. Following is a list of pre-defined character entities from XML specification.
What is an entity in XML?
This means, entities are the placeholders in XML. These can be declared in the document prolog or in a DTD. There are different types of entities and in this chapter we will discuss Character Entity.
What is a numeric character?
Numeric Character Entities. The numeric reference is used to refer to a character entity. Numeric reference can either be in decimal or hexadecimal format. As there are thousands of numeric references available, these are a bit hard to remember.
What is the most preferred type of character entity?
As it is hard to remember the numeric characters, the most preferred type of character entity is the named character entity. Here, each entity is identified with a name. 'Aacute' represents capital character with acute accent. 'ugrave' represents the small with grave accent.
Can XML code use symbols?
Both , HTML and XML, have some symbols reserved for their use, which cannot be used as content in XML code. For example, < and > signs are used for opening and closing XML tags. To display these special characters, the character entities are used.
Why is XML important?
XML also makes it easier to expand or upgrade to new operating systems, new applications, or new browsers, without losing data. With XML, data can be available to all kinds of "reading machines" like people, computers, voice machines, news feeds, etc.
When did XML become a W3C recommendation?
XML became a W3C Recommendation as early as in February 1998.
Does XML have predefined tags?
XML Does Not Use Predefined Tags. The XML language has no predefined tags. The tags in the example above (like <to> and <from>) are not defined in any XML standard. These tags are "invented" by the author of the XML document.
Does XML have a message body?
It has receiver information. It has a heading. It has a message body. But still, the XML above does not DO anything. XML is just information wrapped in tags. Someone must write a piece of software to send, receive, store, or display it:
Does XML do anything?
XML Does Not DO Anything. Maybe it is a little hard to understand, but XML does not DO anything. This note is a note to Tove from Jani, stored as XML: The XML above is quite self-descriptive: It has sender information. It has a message body. But still, the XML above does not DO anything.
Does XML work if new data is added?
Most XML applications will work as expected even if new data is added (or removed).
What is a DTD in HTML 5?
The HTML 5 DTDs define many named entities, references to which act as mnemonic aliases for certain Unicode characters. The HTML 5 specification requires the use of the standard DTDs and does not allow users to define additional entities. In the table below, the "Standard" column indicates the first version of the HTML DTD ...
How many XML characters can be used in a document?
If the document is read by an XML parser that does read external entities, then the five built-in XML character entities can safely be used. The other 248 HTML character entities can be used as long as the XHTML DTD is accessible to the parser at the time the document is read. Other entities may also be used if they are declared in the internal DTD subset.
What does standard column mean in HTML?
In the table below, the "Standard" column indicates the first version of the HTML DTD that defines the character entity reference. To use one of these character entity references in an HTML or XML document, enter an ampersand followed by the entity name and a semicolon, e.g., enter © for the copyright symbol (©).
What is RFC 2070?
The normative reference to RFC 2070 (still found in DTDs defining the character entities for HTML or XHTML ) is historic; this RFC (along with other RFC's related to different part of the HTML specification) has been deprecated in favor of the newer informational RFC 2854 which defines the "text/html" MIME type and references directly the W3C specifications for the actual HTML content.
What is W3C MathML?
The W3C MathML Working Group took over maintenance of the ISO public entity sets, combined with the MathML and documents them in XML Entity Definitions for Characters. This set can support the requirements of XHTML, MathML and as an input to future versions of HTML.
How many character entities can be used in XHTML?
However, the usability of entity references in XHTML is affected by how the document is being processed: If the document is read by a conforming HTML processor, then only the 252 HTML character entities can safely be used.
What is character data in HTML?
In SGML, HTML and XML documents, the logical constructs known as character data and attribute values consist of sequences of characters, in which each character can manifest directly (representing itself), or can be represented by a series of characters called a character reference, of which there are two types: a numeric character reference and a character entity reference. This article lists the character entity references that are valid in HTML and XML documents.
How to use entity reference?
An entity reference is an ampersand (&), followed by the name of the entity, followed by a semicolon (;).
How many internal entities are there in XML?
There are five internal entities which are predefined in internal entities. All xml processors are required to support references to those entities, even if they are not declared. Here is a table containing predefined entities and their replacement text: Entity Name. Replacement Text.
What is the entity declaration?
All entities are declared with the "ENTITY" declaration. The exact format of the declaration distinguishes between internal, external, and parameter entities.
What is internal entity?
Internal Entities. An internal entity is one that is defined locally within a DTD. The basic purpose of an internal entity is to get rid of typing the same content (like the name of the organization) again and again.
What entity reference is used to contain the name of a company?
If you've defined the entity "compname" to contain the name of your company, then you can use it with the following entity reference "&compname;".
Do entities have to be declared in XML?
They may be declared in the DTD, if your XML parser processes the DTD also known as the external subset), or the internal subset.Note: if the same entity is declared more than once, only the first declaration applies and the internal subset is processed before the external subset.
What is an XML external entity attack?
An XML External Entity attack is a type of attack against an application that parses XML input. This attack occurs when XML input containing a reference to an external entity is processed by a weakly configured XML parser. This attack may lead to the disclosure of confidential data, denial of service, server side request forgery, port scanning from the perspective of the machine where the parser is located, and other system impacts.
What is XML 1.0?
The XML 1.0 standard defines the structure of an XML document. The standard defines a concept called an entity, which is a storage unit of some type. There are a few different types of entities, external general/parameter parsed entity often shortened to external entity, that can access local or remote content via a declared system identifier. ...
Where is tainted data allowed?
Tainted data is allowed within the system identifier portion of the entity, within the document type declaration (DTD).
Can XML be validated?
Since the whole XML document is communicated from an untrusted client, it’s not usually possible to selectively validate or escape tainted data within the system identifier in the DTD. Therefore, the XML processor should be configured to use a local static DTD and disallow any declared DTD included in the XML document.
Can fortune get RCE?
If fortune is on our side, and the PHP “expect” module is loaded, we can get RCE. Let’s modify the payload
Does an application need to return the response to an attacker?
Note that the application does not need to explicitly return the response to the attacker for it to be vulnerable to information disclosures. An attacker can leverage DNS information to exfiltrate data through subdomain names to a DNS server that they controls.
What Is Xml?
- XML stands for "extensible markup language". XML is a language designed for storing and transporting data. Like HTML, XML uses a tree-like structure of tags and data. Unlike HTML, XML does not use predefined tags, and so tags can be given names that describe the data. Earlier in t…
What Is Document Type Definition?
- The XML document type definition (DTD) contains declarations that can define the structure of an XML document, the types of data values it can contain, and other items. The DTD is declared within the optional DOCTYPEelement at the start of the XML document. The DTD can be fully self-contained within the document itself (known as an "internal DTD") or can be loaded from elsewh…
What Are XML Custom Entities?
- XML allows custom entities to be defined within the DTD. For example: This definition means that any usage of the entity reference &myentity; within the XML document will be replaced with the defined value: "my entity value".
What Are XML External Entities?
- XML external entities are a type of custom entity whose definition is located outside of the DTD where they are declared. The declaration of an external entity uses the SYSTEMkeyword and must specify a URL from which the value of the entity should be loaded. For example: The URL can use the file://protocol, and so external entities can be loaded from file. For example: XML external en…
What Is An Entity
Use of Entities in XML Document
- Denoting special markup, such as the > and < tags.
- Managing binary files and other data not native to XML.
- Reducing the code in DTD by bundling declarations into entities.
- Offering richer multilingual support.
Rules For Using Legal Entity Markup
- The entity must be declared in the DTD. If you are using anXML document which is not validated against a DTD or schema, thenyou have to declare one within the xml document itself and thismust consi...
- A general entity is referenced within an xml document mustbe surrounded by an ampersand (&) on one end and the semicolon (;)on the other (&myEntity;).
- The entity must be declared in the DTD. If you are using anXML document which is not validated against a DTD or schema, thenyou have to declare one within the xml document itself and thismust consi...
- A general entity is referenced within an xml document mustbe surrounded by an ampersand (&) on one end and the semicolon (;)on the other (&myEntity;).
- The name of an entity must begin with a letter or underscore(_) but can contain letters, underscores, whole numbers, colons,periods and/or hyphens.
- An entity declaration cannot consist of markup that beginsin the entity declaration and ends outside of it .
Types of Entities
- In general, we have three types of entities: internal entities, external entities, and parameter entities.
Internal Entities
- These are entities that refer to entities whose definitions can be found entirely within a document's DTD.
External Entities
- These are entity references that refer to entities whose definitions can be found outside of a document.
Parameter Entities
- These are available within internal or external subsets of DTD. In the subsequent pages, we have discussed each of these entities in detail. Besides the type of Entities mentioned above, we find it necessary to discuss the Document Entity of an xml document to be discussed specially. The document entity is the most important entity in an xml document and is actually one of only two …
Predefined Character Entities
Numeric Character Entities
- The numeric reference is used to refer to a character entity. Numeric reference can either be in decimal or hexadecimal format. As there are thousands of numeric references available, these are a bit hard to remember. Numeric reference refers to the character by its number in the Unicode character set. General syntax for decimal numeric reference i...
Named Character Entity
- As it is hard to remember the numeric characters, the most preferred type of characterentity is the named character entity. Here, each entity is identified with a name. For example − 1. 'Aacute' represents capital character with acute accent. 2. 'ugrave' represents the small with grave accent.