Cybersecurity Glossary

XHTML is short for extensible hypertext markup language. XHTML is a hybrid between XML and html and designed for network devices as a method of displaying web pages on network and portable devices. XHTML was first released January 26, 2000.

XML is short for extensible markup language. XML is a specification developed by w3c starting with the recommendation on February 10, 1998. XML is similar to html, XML uses tags to markup a document, allowing the browser to interpret the tags and display them on a page. Unlike HTML, XML language is unlimited (extensible) which allows self-defining tags and can describe the content instead of only displaying a page’s content. Using XML other languages such as RSS and MathML have been created, even tools like XSLT were created using XML.

XMPP which stands for extensible messaging and presence protocol, is a communications protocol for messaging systems. It is based on XML, storing and transmitting data in that format. It is used for sending and receiving instant messages, maintaining buddy lists, and broadcasting the status of one’s online presence. XMPP is an open protocol standard. Anyone can operate their own XMPP service, and use it to interact with any other XMPP service. The standard is maintained by XSF, the XMPP standards foundation.

XMT is also called transmit. XMT is the method of sending data to an alternate computer or device.

Yottabyte is abbreviated as YB. A yottabyte is equal to 1,208,925,819,614,629,174,706,176 (280) bits, or 1,000,000,000,000,000,000,000,000 (1024) bytes and is the largest recognized value used with storage.

Y2K is short for the year 2000 bug or the millennium bug. Y2K is a warning first published by Bob Bemer in 1971 describing the issues of computers using a two-digit year date stamp.

A Ymodem is a file-transfer protocol developed by Chuck Forsburg that is similar to the enhanced 1k version of Xmodem. Ymodem sends data in 1024-byte blocks, allows for multiple file transmissions at once, performs cyclic redundancy checks (CRC), and can reduce the transfer size to compensate for poor connections.

A zombie computer is a computer connected to the internet that has been compromised by a hacker, a computer virus, or a trojan horse. Generally, a compromised machine is only one of many in a botnet, and is used to perform malicious tasks of one sort or another under remote direction.

A zero-day (or zero-hour or day zero) attack is a computer threat that attempts to manipulate the computer application vulnerabilities that are undisclosed to the software developer. Zero-day exploits is the actual code that can use a security hole to carry out an attack. These exploits are used or shared by attackers before the software developer knows about the vulnerability.

The zero day or day zero is the day a new vulnerability is made known. In some cases, a zero day exploit is referred to as an exploit for which no patch is available yet. Day one is a day at which the patch is made available.