Inspired by https://www.intego.com/mac-security-blog/mac-os-x-security-features-timeline/

mac_security_timeline.md

OS X Tiger 10.4 (April 2005)

• Added Download Validation
• Added Access Control Lists (ACLs) Ars TechRepublic
• Added file extended attributes (xattr)

OS X Leopard 10.5 (October 2007)

• Added File Quarantine
• Added ability to code sign

OS X Snow Leopard 10.6 (August 2009)

• Added XProtect ("safe downloads lists")

OS X Lion 10.7 (July 2011)

• Added FileVault 2 (Full Disk Encryption)
• Improved ASLR
• Added App Sandbox
• Removed Rosetta (PowerPC Support)

OS X Mountain Lion 10.8 (July 2012)

• Added Gatekeeper
  • Also present in final version of OS X Lion (10.7.5)
• Added Location Services
• Improved App Sandboxing
• Improved XProtect (September)
  • Blocks outdated Flash and Java browser plugins
  • Backported to Lion and Snow Leopard

OS X Mavericks 10.9 (October 2013)

• Added iCloud Keychain
• Added requirement for Kexts to be signed
• Added SMB2 suppoort
  • Default file sharing protocol

OS X Yosemite 10.10 (October 2014)

• ¯_(ツ)_/¯

OS X El Capitan 10.11 (September 2015)

• Added System Integrity Protection (SIP)
• Added App Transport Security (ATS)
• Updated XProtect (January 2016)
  • Blocks outdated Silverlught browser plugin
  • Backported to Yosemite (10.10), Mavericks (10.9), Mountain Lion (10.8), Lion (10.7) and Snow Leopard (10.6)

macOS Sierra 10.12 (September 2016)

• Updated Gatekeeper
  • Remove install from anywhere
  • Added ability to sign disk images (.dmg)
  • Added path randomisation
• Removed support for VPN Point-to-Point Tunneling Protocol (PPTP)

macOS High Sierra 10.13 (September 2017)

• Added weekly firmware integrity checks
• Changed File System to Apple File System (APFS)
• Removed support for SHA1 TLS Certificates
• Added requirement for user appoval of Kext loading