The FREE Cybersecurity Glossary by Thor Pedersen!

X.25: A packet-switched network protocol used in public data networks that provides error detection and recovery, flow control, and routing for reliable data transmission.

X.25 interface: A protocol suite for packet-switched network communications, X.25 facilitates data transmissions across long distances. It was widely used in the pre-Internet era for connecting terminals to computers, providing error correction and flow control. Although largely superseded by newer technologies, X.25 laid the groundwork for modern network communication standards.

X.500: X.500 is a standard for directory services used to store and organize information about users, resources, and services on a network. Examples of X.500-based directories include Active Directory and LDAP.

X.509 V3: A standard for public key certificates, which are used to verify the identity of a user or device in a network. It is used in secure communication protocols such as SSL/TLS, which require the use of certificates for authentication and encryption. Examples of X.509 V3 certificates include SSL/TLS certificates, digital signatures, and client authentication certificates.

Xmas Attack/Scan: A network scanning technique that manipulates the TCP header flags, sending packets with the FIN, URG, and PSH flags set—resembling a lit-up Christmas tree. It is designed to probe for responses that can reveal information about active services on network devices, potentially identifying vulnerable targets for further exploits.

XML Injection: An attack where malicious XML code is inserted into a system, exploiting insecure processing of XML input by an application. This can affect the logic of XML parsers, leading to unauthorized access, data exposure, or service disruption. It's distinct from other injection attacks by specifically targeting XML parser vulnerabilities.