This is detected, I have been using this external ESP hack for just 4 days and yesterday I was banned.
When I click play in multiplayer menu it will tell me "The Modern Warfare 3 server is unavailable at this time, please try again later." and I saw that I have "Ban(s) on record". I went into further details and saw that it was a ban for Modern Warfare 3. Never used any other cheat except this.