The Malware Museum
Back in the days a lot of thought and ingenuity was put into making these viruses. For instance, the Friday 13th [1][2][3] virus:<p>* was only 419 bytes long<p>* infected both .COM and .EXE, increasing the size of the former by only 1813 bytes<p>* on infection, became memory resident (using only 2kb of memory)<p>* hooked itself into interrupt processing and other low level DOS services to, for instance, suppress the printing of console messages in failure cases (like trying to to infect a file on a read-only floppy disk)<p>* activated itself every friday 13th and deleted programs used that day<p>It still managed to spread itself worldwide (mostly via floppy disk sharing as the world wide web didn't exist yet) and went mainstream enough for the broadcast news to advise people not to turn on their computers on that date or to push the date one day ahead.<p>All that in 419 bytes, about a third of the size of this post.<p>[1] <a href="https://en.wikipedia.org/wiki/Jerusalem_%28computer_virus%29" rel="nofollow">https://en.wikipedia.org/wiki/Jerusalem_%28computer_virus%29</a><p>[2] <a href="https://www.f-secure.com/v-descs/jerusale.shtml" rel="nofollow">https://www.f-secure.com/v-descs/jerusale.shtml</a><p>[3] <a href="http://www.pandasecurity.com/mediacenter/malware/famous-virus-history-friday-13th/" rel="nofollow">http://www.pandasecurity.com/mediacenter/malware/famous-viru...</a>