A file infector is a type of computer virus that embeds its malicious code into executable files, such as those with .COM or .EXE extensions.
Understanding File Infectors
File infectors are a type of malware that primarily targets executable files on a computer system. Unlike other viruses that might target data files or the boot sector of a hard drive, file infectors specifically modify or append themselves to executable programs. This allows the virus to spread whenever the infected program is executed.
How File Infectors Work:
- Infection Process: The virus attaches itself to an executable file. This can be done by either appending its code to the end of the file, overwriting parts of the file, or inserting itself into unused sections of the file.
- Activation: When a user runs the infected executable, the virus code is executed first. This allows the virus to replicate and infect other executable files on the system or across a network.
- Replication: The virus searches for other executable files to infect. This process can continue until many files on the system are infected.
- Payload (Optional): Some file infectors have a malicious payload that is triggered after a certain condition is met (e.g., a specific date or number of infections). This payload could cause data corruption, system crashes, or other unwanted behavior. However, many simply replicate.
Types of File Infectors:
- Appending Viruses: These viruses add their code to the end of the host file. They typically modify the program's entry point to execute the virus code before the original program code.
- Overwriting Viruses: These viruses overwrite parts of the host file with their own code. This type of virus is often destructive, as it can damage the original program, potentially rendering it unusable.
- Cavity Viruses: Also known as spacefiller viruses, these viruses insert their code into unused sections or "cavities" within the host file without increasing its overall size.
Examples:
While specific historical file infector examples are less relevant due to outdated technologies, understanding the principles remains crucial. Consider a hypothetical scenario:
- A user downloads a seemingly legitimate program (e.g., an image editor) that is unknowingly infected with a file infector.
- Upon running the program, the virus executes, replicates itself, and infects other .EXE files on the computer.
- Each time an infected .EXE file is run, the virus continues to spread.
Mitigation:
- Antivirus Software: Using up-to-date antivirus software is the most effective way to detect and remove file infectors.
- Safe Computing Practices: Be cautious when downloading and running executable files from untrusted sources.
- Regular Scanning: Perform regular system scans with your antivirus software.
In summary, a file infector is a malicious program that targets executable files (.COM, .EXE) to replicate and spread, potentially causing harm to the system or simply replicating itself.
