• Your computer can be infected even if files are just copied
• Can be Polymorphic.
• Can be memory or non-memory resident
• Can be a stealth virus
• Viruses can carry other viruses
• Can make the system never show outward signs
• Can stay on the computer even if the computer is formatted.
• Most of the viruses operate in two phases.
1. Infection Phase – In this phase virus developers decide
- When to Infect program
- Which programs to infect
• Some viruses infect the computer as soon as virus file installed in computer.
• Some viruses infect computer at specific date,time or perticular event.
• TSR viruses loaded into memory & later infect the PCs.
2. Attack Phase - In this phase Virus will
- Delete files.
- Replicate itself to another PCs.
- Corrupt targets only
Virus Indications
• Following are some of the common indications of Virus when it infects system.
• Files have strange name than the normal.
• File extensions can also be changed.
• Program takes longer time to load than the normal.
• Computer’s hard drives constantly runs out of free space.
• Victim will not be able to open some programs.
• Programs getting corrupted without any reasons.
Virus Types
• Following are some of the common indications of Virus when it infects system.
• Macro Virus – Spreads & Infects database files.
• File Virus – Infects Executables.
• Source Code Virus – Affects & Damage source code.
• Network Virus – Spreads via network elements & protocols.
• Boot Virus – Infects boot sectors & records.
• Shell Virus – Virus Code forms shell around target host’s genuine program & host it as sub routine.
• Terminate & stay resident virus – remains permanently in the memory during the work session even after target host is executed & terminated.