Similarities between biological and computer viruses

Slashdot linked to this CNet article on the similarities between computer viruses and their biological brethren. Drawing on a botanical analaogy, the article makes the argument that the existence of "digital monocultures" increases the risk of emergence and proliferation of malware:

Computer security experts see similarities between the way a disease can devastate agricultural crops and the way a virus can attack Internet infrastructure. The reliance on one type of technology, software or protocol has created digital "monocultures," a phrase borrowed from botany that refers to ecosystems vulnerable to disastrous harm from a single disease... Just as biologists advise farmers to diversify their plantings, computer researchers believe that developers should be given tools to vary characteristics of the same program so that not all would be hobbled by a virus written for a specific version... "You only get epidemics when your target populations are alike enough that they can all get the same disease," said Dan Geer, chief scientist at information security firm Verdasys

Obvious examples of digital monocultures: predominance of Windows at the OS level, of Outlook at the application level, of SNMP at the protocol level, etc.

Also interesting is this letter Contagion on the Internet to a journal titled 'Emerging Infectious Diseases' that draws parallels between biological and computer viruses in terms of their emergence, mutation, propagation and mode of action. It also suggests ways in which computer security can learn virus control strategies from the immune system and from immunology. Here are some of the lessons:
* Good hygiene helps: periodically back up data, avoid installing suspicious software, etc.
* Avoid monocultures if at all possible: use a Mac rather than a PC, for instance. Somewhat infeasible as a strategy.
* "Pathogens do not reinvent the wheel. Virulence genes are constantly “stolen” and reused." Self-evident - as soon as a vulnerability is discovered, it should be plugged, regardless of the contagiousness or deadliness of the worm/virus that exploits it.
* R&D ideas: adaptive immunity software that learns from exposure, "“virtual vaccines” that are beneficial to the computers carrying them (e.g., by blocking preferred sites of entrance for viruses or repairing viral damage automatically) and let these “good” microbes circulate on the Internet just as malignant viruses do."