Download Links:
Download Security Update 2016-003 (10.11.6) - Jan 17, 2017:
https://support.apple.com/kb/DL1907?locale=en_US
http://support.apple.com/downloads/DL1907/en_US/secupd2016-003elcapitan.dmg
Download Security Update 2016-003 Supplemental (10.11.6) - Jan 17, 2017:
https://support.apple.com/kb/DL1908?locale=en_US
http://support.apple.com/downloads/DL1908/en_US/secupd2016-003supplemental.dmg
About the security content - Jan 17, 2017:
https://support.apple.com/en-us/HT207423
https://support.apple.com/kb/DL1907?locale=en_US
http://support.apple.com/downloads/DL1907/en_US/secupd2016-003elcapitan.dmg
Download Security Update 2016-003 Supplemental (10.11.6) - Jan 17, 2017:
https://support.apple.com/kb/DL1908?locale=en_US
http://support.apple.com/downloads/DL1908/en_US/secupd2016-003supplemental.dmg
About the security content - Jan 17, 2017:
https://support.apple.com/en-us/HT207423