DefinitionCyber espionage can be defined as the practice of accessing and stealing secret information, without the consent of its holders, using internet and information technology to their advantage. It is often used for accessing economic, political, strategic or military data to gain advantage over the target entity, be it an individual, organization or state.Cyber-espionage techniques have become much more sophisticated with the advancement in technology. Unsecured systems are susceptible to cyber attacks that can be conducted by malicious users from any place and at any time. The worst part of a cyber espionage attack is that it can go undetected for a long period of time resulting in a lot of damage. The victim may lose valuable information before even realising that it has been targeted by cyber attackers.  Nations, government, private and public companies, or even an individual can become a victim of cyber espionage.Tools of cyber espionageOver the last few years, cyber attackers have come up with a number of sophisticated and advanced tools for hacking into the computer networks and systems of their targets. Cyber espionage can be conducted through cracking techniques, spyware and malware etc.  Attackers may use malware to build a backdoor through which they can penetrate into the targeted networks. They may also attack the victims by exploiting existing vulnerabilities in the application software or operating system and using a combination of encryptions techniques and stealth programming.Cyber espionage: Potential TargetsCyber attackers may attack relevant sources to steal sensitive data such as military information.Enemy State sponsored hackers may target government computers to steal information.Attackers may try to access and steal data of people working for the private, government or military organization.Attacks aiming at stealing the intellectual property of organizations may also be conducted.Large spy networks may target multiple systems in various countries.Malicious users may attack vital industries and organizations such as energy businesses.Attackers may also target and spy on VIPs or government executives of a nation.