Backdoor Viruses and Trojans
Backdoors are one of the most common forms of vulnerabilities often exploited by hackers to gain access to computer systems. Malwares which utilize backdoors completely negate the implement authentication system and gain easy access. The term backdoor refers to the existence of an unforeseen backdoor which was left as a part of faulty software design or oversight by software engineers.
Through the use of backdoors, cybercriminals gain remote access to sensitive file systems such as various vital applications, databases, file servers and other. This allows them to remotely control the entire system from geographically diverse locations. They can also update their version of attacks and infect the systems further.
Detection of corrupt files and malware that have entered through the backdoor are difficult to detect due to their obfuscated nature. They usually take advantage of some weakness on web applications, and some of their various activities are mentioned below.
- Theft of sensitive data such as identity, bank account details, web history, emails, and other personal data.
- Defacing and vandalizing of websites with explicit and derogatory content.
- Hijacking of servers is thereby gaining access to all web applications and also the traffic that is received.
- DDOS attacks become extremely harmful when utilized through backdoors. They usually stop services for ransom.
- After gaining access to online systems through backdoors, hackers can further infect visitors and incoming traffic.
- Various types of APT or advanced persistent threat assaults.
- Installation of a backdoor Trojan
The most popularly used method of exploiting backdoors is known as remote file inclusion or RFI. RFI is a form of attack vector that uses the inherent vulnerabilities within file systems that are dynamically linked to external scripts. In case of an RFI attack, the application is fooled into downloading a backdoor Trojan deployed from a remote host.
Hackers deploy scanners that look for vulnerabilities in website and online application's code for an opening. Websites and applications with outdated security systems and old patches are ideal targets for such scanners and backdoor Trojans. The vulnerability, once identified is exploited, and a backdoor is installed on the server which then grants remote access to the hacker. Once the backdoor has been installed, it can be accessed by the hacker at any point in time. Backdoors once successfully installed remain operational even after the systems have been patched. This makes them extremely dangerous especially for corporate computer systems with a bulk of sensitive data.
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