A couple ideas that went nowhere
I suspect a lot of people in academia end up having a lot of ideas and projects that went nowhere for any number of reasons – maybe there were insurmountable technical challenges, maybe the right person to work on it never materialized, or maybe it just got crowded out by other projects and never picked back up. Here are a couple of mine. For each I'll try to indicate why it fell by the wayside, and whether I think it could be resurrected (if you're interested in doing some idea necromancy, let me know! :)). Detecting Flush+Flush Among the flurry of microarchitectural side channel attacks that eventually culminated in the devastating Spectre and Meltdown attacks was one that has received relatively little attention: Flush+Flush. The base of the attack is the observation that clflush takes a different amount of time depending on whether the address to be flushed was already in the cache or not. Gruss et al. had a nice paper on this variant of the attack at DIMVA 2016