It has been 26 years to the day when the computing world was introduced to its first virus: The Brain.

The Brain was a boot sector virus that was written on and for floppy disks and spread by the exchange of disks between users. The Brain which was also known as LeHore or Pakistani Flu and Pakistani Brain, infected Microsoft MS-DOS-based computers and once installed would fill up the floppy, slamming its performance or rendering it useless.

The virus was written by two Pakistani brothers, Basit Farooq Alvi and Amjad Farooq Alvi, who have over the years said the Brain was not a virus but mechanism for them to protect their medical software from piracy.

Amjad Farooq Alvi told Bloggerine just last year: "Our work was not intended to harm anyone. It was a friendly virus. We wrote it for our medical software to be protected from piracy, and was on a remote widespread. We did believe it would spread, but [we were] not filled with expectations [it would]. Brain was a virus, created for protection from copyright infringers only, for our medical software."

"The novelty of this virus is that it checked the significant bits of BIOS, if they were clear, it didn't infect the disk. The sole purpose for it was to track and stop illegal copies of disk. We never intended for personal or financial gain. It was just an experimental approach, and surely of its outcome we were quite uncertain about. When the virus had widespread, people outrageously called us asking us to disinfect the virus. Our attempt to make them understand that the virus is not malicious but a friendly-one was successfully accepted and understood."

Still the Brain ignited a storm of boot sector viruses, also known as Master Boot Record infections, that continued to plague the industry for years. Much more destructive MBR virus types were to follow. The most infamous was Michelangelo that struck in April 1991 mostly in Europe.

From Network World: "Today, the hard disk boot sector is a rare place to encounter malware, the notable exception in recent times being the nasty Mebroot rootkit of 2008. From time to time, older malware does pop back into existence when experts least expect it, the infamous example being the 'Stoned.Angelina' MBR virus that reportedly sneaked on to 100,000 Medion laptops in 2007."

"Stoned.Angelina originally dated from January 1994, a time period that might also explain Zimuse, which ESET believes bears a striking resemblance to the 'One-half' virus that came out of Slovakia in 1995."