Sometimes referred to as a multipartite virus, the hybrid virus is one of the more difficult types of computer virus to bring under control. Essentially, the hybrid virus will combine elements of other virus programs in a new combination that will often slip past protections that would stop the original component viruses. Generally, a hybrid virus is capable of infecting both system sectors and program files, making it especially difficult to locate and remove from a system.
In many cases, the hybrid virus will include elements of both file infectors and boot infectors. The idea behind this approach is to launch a two-pronged attack on the system. As the multi-part virus enters the system, elements settle into program files, while at the same time identifying and infiltrating various sections of the operating system. This means that each time the executable file imbedded with the hybrid virus runs, the result is an activation sequence that helps the virus to proliferate.
At the same time, the hybrid virus normally works into the section of the hard drive that controls the start up procedures for the computer. As with the infected program files, the virus is activated each time the system is booted up. Over time, this will damage the operation of the system, and possibly shut it down altogether.
The dual nature of the hybrid virus makes it extremely difficult to remove once it is in place. Unless all elements of the virus are removed, any remaining presence will quickly regenerate and re-infect the entire system. For this reason, special care should be taken to clean the system thoroughly, and making sure to conduct a virus check immediately after the cleaning takes place.
Of course, the best way to deal with a hybrid virus is to not become infected in the first place. One way to minimize the chances for infection is to be extremely careful about opening attachments that are of a suspicious nature. Care should also be taken to keep anti-virus software updated, and to not download programs from any online source that is not familiar and trusted.