banned due to the use of malicious 3rd party programs or modifications... That I did not do..

I get an email today saying:

Hello Summoner,

Your account: ------ was banned due to the use of malicious 3rd party programs or modifications to your League of Legends client.

I have not played in almost two months, and only launched the client to keep it up to date, so why did I get banned...? What would cause this to happen, and what can I do about it? Anyone know if there is some program that might set a false positive? (possibly discord?)