BackdoorTrojaner

BackdoorTrojaner is a term used to describe a class of malware that functions as a backdoor, providing unauthorized remote access to a computer or network. It is typically delivered as a Trojan horse, appearing as legitimate software or hidden within a compromised application, and activates after installation without the user’s informed consent. Once installed, the backdoor component enables an attacker to issue commands, access files, and control system resources, often while attempting to evade detection.

Backdoor trojans may operate covertly by running in the background, using persistence mechanisms such as startup entries, services, scheduled tasks, or kernel modifications. They commonly establish outbound network connections to command-and-control servers, enable remote shells, or deploy additional payloads. Some variants include data exfiltration, keystroke logging, credential harvesting, or the ability to move laterally within a network to compromise other hosts.

Common infection vectors include phishing emails with malicious attachments or links, drive-by downloads from compromised websites, software bundling, supply-chain compromises, and exploiting unpatched vulnerabilities. They are used in criminal campaigns for espionage, data theft, ransomware delivery, or botnet creation, and are distinct from legitimate remote administration tools intended for authorized use.

Detection and prevention focus on defense-in-depth: keeping systems updated, using reputable endpoint security and EDR solutions, monitoring for unusual outbound traffic and process behavior, and applying least-privilege access and multi-factor authentication. Regular backups, network segmentation, application whitelisting, and incident response planning reduce risk and aid recovery.

Notable examples and history: the concept has existed since the late 1990s with early backdoors such as Back Orifice and SubSeven, and continues with a variety of modern remote access trojans used by criminal groups and adversaries.