They did not, at least not until much later, many years after AOL waned in popularity -- possibly in part due to lack of money to pay enough engineers. Initial

They did not, at least not until much later, many years after AOL waned in popularity -- possibly in part due to lack of money to pay enough engineers. Initially AOL's was done (GUI and non-GUI functionality) via their client API called FDO and sent assembled packets out like everything else. AIM on the other hand was a classic simple GUI app using a different protocol and used none of AOL's FDO stuff. Much later AOL used some OSCAR (AIM) libraries to piggy back the AOL client on-to AIM for buddies and IMs, but even so these were not a part of the exploits that kept popping up for AIM, and long after AIM's drop in popularity as well.