Bomber is a complicated virus, which is not known to be in the wild. It stays resident in memory and infects COM files when they are executed.
Bomber contains the following unencrypted text strings:
COMMANDER BOMBER WAS HERE [DAME] [DAME]
Bomber inserts its code in the middle of the host file and builds a complicated series of branching commands to transfer the flow of the program to the virus code, which is unencrypted. The detection of such virus would force some scanners to scan the whole file from the beginning to the end - which would be enough to make them unusably slow.
Bomber contains routines which generate random code, which are inserted into random positions in the host file. These fragments are linked by a series of complicated branching commands. Almost all legal 80x86 instructions are used in these code fragments, making Bomber a difficult virus to detect efficiently.
One_Half virus uses a similar infection method.
Disinfection & Removal
Description Created: Mikko Hypponen, F-Secure