Non-Resident Virus:
A Non-Resident Virus is a type of computer virus that does not embed itself into a computer’s memory or stay active in the system’s RAM. Unlike resident viruses, non-resident viruses do not remain running after the infected program has finished executing. Instead, they work by directly infecting files on disk when they are executed, causing damage to the file and potentially spreading to other files.
Infection Process:
The infection process of a non-resident virus typically follows these steps:
- Attachment: The non-resident virus attaches itself to a host file, such as an executable (.exe) or a document (.doc), by modifying the file’s code.
- Execution: When the infected program is executed, the virus’s code is triggered and executed.
- Infection: The virus code then searches for other files on the system, removable media, or network shares and infects them by modifying their code.
- Propagation: Non-resident viruses spread by infecting other files and relying on these infected files to be transferred or shared to infect more systems.
Characteristics of Non-Resident Viruses:
- No Memory Presence: One of the key characteristics of non-resident viruses is that they do not reside in the computer’s memory. They only execute when the infected program runs.
- Infection on Execution: Non-resident viruses infect files at the time of execution, making them more noticeable than resident viruses, which often operate stealthily.
- Fast Propagation: Non-resident viruses can spread rapidly as they rely on infected files to carry and transfer their code to other systems.
- Visible Modifications: Infected files often show visible modifications, which can alert users to the presence of the virus.
Prevention and Removal:
Preventing and removing non-resident viruses require specific measures:
- Antivirus Software: Use reputable and updated antivirus software with real-time scanning to detect and remove non-resident viruses as they attempt to infect files.
- File Backup: Regularly back up your important files to a secure location. In case of infection, you can restore clean versions of the files.
- Exercise Caution: Be cautious when downloading files from untrusted sources, opening email attachments, or using pirated software, as these are common vectors for virus infections.
- Keep Software Updated: Regularly update your operating system and applications to patch any security vulnerabilities that viruses might exploit.
In case of infection:
- Quarantine and Removal: If a non-resident virus is detected, use the antivirus software to quarantine and remove the infected files.
- Scan and Clean External Media: Scan any external media, such as USB drives, CDs, or DVDs, before accessing them on your computer to prevent further infections.
Non-resident viruses were more common in the earlier days of computing when antivirus software was less advanced. However, modern antivirus tools and security measures have become more effective at detecting and removing these types of viruses. Nonetheless, it’s essential to maintain a proactive approach to cybersecurity to minimize the risk of infections and protect your data and systems.