[SDPhantom]

When it comes to the chat system, there are many attack vectors they can eventually move to with ease. One thing that can be done is completely nullify the RunScript() and DevTools_DumpCommand() functions while a chat event is being handled.

local FuncList={
    "RunScript";
    "DevTools_DumpCommand";
};
 
local FuncCache={};
for k,v in ipairs(FuncList) do FuncCache[v]=_G[v]; end
 
local function DummyFunc() end
local OldHandler=ChatFrame_OnEvent;
local InChatEvent=false;
 
local EventFrame=CreateFrame("Frame");
EventFrame:RegisterEvent("ADDON_LOADED");
EventFrame:SetScript("OnEvent",function()
    for k,v in ipairs(FuncList) do
        if not FuncCache[v] then
            FuncCache[v]=_G[v];
            if InChatEvent then _G[v]=DummyFunc; end
        end
    end
end);
 
function ChatFrame_OnEvent(...)
    for k,v in pairs(FuncCache) do _G[k]=DummyFunc; end
    InChatEvent=true;
    OldHandler(...);
    InChatEvent=false;
    for k,v in pairs(FuncCache) do _G[k]=v; end
end

To protect more functions, add them to the FuncList table.