A backdoor is a method used to bypass standard authentication or encryption mechanisms within a computer system.
Often found in applications that enable remote access, backdoors can be exploited by attackers to infiltrate a client’s network without detection. Once a server has been compromised, there’s a high possibility that the attacker has installed a backdoor to ensure easy re-entry in the future.
Cybercriminals commonly use backdoors to gain stealthy access to systems and maintain control over compromised infrastructure.
These backdoors may be intentionally embedded by individuals or organizations—either secretly or as part of documented features—to access systems and data. Regardless of the intent, backdoors pose a significant information security risk.
One of the most effective ways attackers introduce backdoors is through Remote File Inclusion (RFI). They may also carry out phishing attacks to trick users into downloading a trojan, which in turn grants the attacker the ability to establish a persistent backdoor connection.
What are the impacts of common backdoors?
Common backdoors have many negative impacts which affect the encryption system within a computer system.
1. Execute malicious code
Attackers can run unauthorized scripts or commands on the server, allowing them to manipulate files, escalate privileges, or control system behavior.
2. Make the web application unstable
Continuous exploitation or injection of harmful commands can degrade performance, crash services, or cause erratic behavior, leading to poor user experience or downtime.
3. Perform Remote Command Execution (RCE)
Gaining RCE access allows attackers to execute system-level commands remotely—effectively giving them full control of the server.
4. Exploit Advanced Persistent Threat (APT) assaults
Sophisticated attackers may establish long-term footholds within the network to quietly monitor, harvest data, and plan further attacks over time.
5. Perform data theft
Attackers can extract sensitive data such as login credentials, customer records, payment information, and proprietary files.
6. Implement Distributed Denial of Service (DDoS) attacks
Compromised servers may be used as bots in a DDoS network, targeting other systems or services to exhaust their resources and cause outages.
How can you prevent common backdoors?
1. Use firewalls to block unauthorized entry points
Deploy firewalls that strictly control traffic and block all entry points by default, allowing access only to authorized users and trusted IP addresses. Configuring rules and access control lists (ACLs) helps ensure only legitimate traffic reaches your applications and servers.
2. Enable continuous network monitoring
Implement network monitoring tools that can detect suspicious behavior, unusual traffic patterns, or unauthorized access attempts in real-time. Early detection through anomaly detection systems or SIEM (Security Information and Event Management) platforms can significantly reduce the risk of long-term compromises.
3. Use an anti-malware solution
Protect your systems with updated anti-malware software that can detect, quarantine, and remove known threats such as trojans, rootkits, and keyloggers. Modern solutions also include heuristic analysis to catch unknown threats based on behavior.
4. Ensure firewall protection for every device
Extend firewall protection beyond the server level—every connected device, including employee laptops, mobile devices, and IoT systems, should have its own firewall or be behind a centrally managed one. This helps in maintaining a zero-trust environment, where no device is inherently trusted.
