With an increasing global reliance on technology, from managing national electrical grids to ordering
supplies for troops, the security of cyber world become an important issue worldwide. In this paper,
an e-epidemic SEI1I2R1R2 (Susceptible-Exposed-Infectious class-1 (I1) - Infectious class-2 (I2) - Removed
class (R1) - Recovered class (R2)) model for the transmission of malicious codes in a computer network is
developed to have a better understanding of removed class on Cyber war. An analysis of the basic reproduction
number has been made and the global stability of an attack-free state is established. Furthermore, initial
simulation results show the system behavior, stability analysis for attack-free state, impact of removed class
in the network for minimizing the infection and the positive impact of increasing security measures on malicious
codes propagation in computer network. Efficiency of antivirus software and crashing of the nodes due
to attack is critically analyzed. Cyber war against computer networks are an important research area because
of the security strategies.