Need suggestion on my I485 case

[whichwich]

Hi All, my eb1a 140 was approved on 2015, and I485 was submitted with RD 5/18/2015. It took more than one year on the status of fingerprint received, during which time I did a lot of SR, infopass, congresswoman, phone, and at last I contacted ombudsman office, then soon my case was transferred to local office on 6/30/2016. Later on I went to infopass to my local and was told my case was sent to security check on 8/3/2016, and pending on it until now.
Does any one have any idea what this security check is and how long it may take? Do I need to go for WOM on my case or wait until 2 years?
Thank you all.