Backdoor malware is generally classified as a Trojan. A Trojan is a malicious computer program pretending to be something it's not for the purposes of delivering malware, stealing data, or opening up a backdoor on your system. Much like the Trojan horse of ancient Greek literature, computer Trojans always contain a nasty surprise.
Trojans are an incredibly versatile instrument within the cybercriminal toolkit. They come under many guises, like an email attachment or file download, and deliver any number of malware threats.
To compound the problem, Trojans sometimes exhibit a worm-like ability to replicate themselves and spread to other systems without any additional commands from the cybercriminals that created them. Take, for example, the Emotet banking Trojan. Emotet got its start in 2014 as an information stealer, spreading across devices and stealing sensitive financial data. Since then Emotet has evolved into a delivery vehicle for other forms of malware. Emotet helped make the Trojan the top threat detection for 2018, according to the State of Malware report.
In one example of backdoor malware, cybercriminals hid malware inside of a free file converter. No surprise—it didn't convert anything. In fact, the download was designed solely to open up a backdoor on the target system. In another example, cybercriminals hid backdoor malware inside of a tool used for pirating Adobe software applications (let that be a lesson on software piracy). And in one final example, a seemingly legitimate cryptocurrency ticker app called CoinTicker worked as advertised, displaying information about various forms of cryptocurrency and markets, but it also opened a backdoor.
Once cybercriminals have their foot in the door, they might employ what's known as a rootkit. A rootkit is a package of malware designed to avoid detection and conceal Internet activity (from you and your operating system). Rootkits provide attackers with continued access to infected systems. In essence, the rootkit is the doorstopper that keeps the backdoor open.
Trojans are an incredibly versatile instrument within the cybercriminal toolkit. They come under many guises, like an email attachment or file download, and deliver any number of malware threats.
To compound the problem, Trojans sometimes exhibit a worm-like ability to replicate themselves and spread to other systems without any additional commands from the cybercriminals that created them. Take, for example, the Emotet banking Trojan. Emotet got its start in 2014 as an information stealer, spreading across devices and stealing sensitive financial data. Since then Emotet has evolved into a delivery vehicle for other forms of malware. Emotet helped make the Trojan the top threat detection for 2018, according to the State of Malware report.
In one example of backdoor malware, cybercriminals hid malware inside of a free file converter. No surprise—it didn't convert anything. In fact, the download was designed solely to open up a backdoor on the target system. In another example, cybercriminals hid backdoor malware inside of a tool used for pirating Adobe software applications (let that be a lesson on software piracy). And in one final example, a seemingly legitimate cryptocurrency ticker app called CoinTicker worked as advertised, displaying information about various forms of cryptocurrency and markets, but it also opened a backdoor.
Once cybercriminals have their foot in the door, they might employ what's known as a rootkit. A rootkit is a package of malware designed to avoid detection and conceal Internet activity (from you and your operating system). Rootkits provide attackers with continued access to infected systems. In essence, the rootkit is the doorstopper that keeps the backdoor open.