By Johannes B. Ullrich, Ph.D. Upgrading Security to MacOS Sierra
https://isc.sans.edu/forums/diary/Getting+Ready+for+macOS+Sierra+Upgrade+Securely/21465/
PCI PIN Transation Security / Point of Interaction Update
https://www.pcisecuritystandards.org/documents/PCI_PTS_POI_SRs_v5.pdf
IMAPS Scans
https://isc.sans.edu/forums/diary/Ongoing+IMAP+Scan+Anyone+Else/21463/
More Here