CISSP Tip 1
Yasser Auda
Cisco VIP , .:|:.:|:. CCIE#45694 CCSI#34215, CISSP, MSc Computer Networking & Cyber Security
Fail-safe vs Fail-secure in three different domains or topics
Physical Security
Doorways with automatic locks can be configured to be fail-safe or fail-secure.
fail-safe setting means that if a power fail , the doors default to being unlocked.
(protecting people is important more than anything)
fail-secure setting means that if a power fail , the doors default to being locked .
(If people do not need to use this door for escape during an emergency, importance priority goes to protecting Assets)
when it comes to doors we could see a third term "fail-soft"
fail-soft locks default to being locked or unlocked depending on the sensitivity of the data and systems in an area , like open from inside only doors
Systems & Networking Devices
Systems (ex:Firewall / IPS systems) can be designed so that they fail in a fail-secure state or a fail-open state.
A fail-secure (aka fail-close) system will default to a secure state in the event of a failure, blocking all access. (security is important more than availability )
A fail-open system will fail in an open state, granting all access. (availability is important more than security)
Software Security (OS)
Fail-secure and fail-open In spite of the best efforts of programmers, product designers, and project managers, developed applications
programmers should design into their code a general sense of how to respond to and handle failures.
There are two basic choices when planning for system failure:
The fail-secure failure state puts the system into a high level of security and possibly even disables it entirely until an administrator can diagnose the problem and restore the system to normal operation (closing just the application or possibly stopping the operation of the entire host system.). this is the common used option . example : windows Blue Screen of Death (BSOD).
The programmer should consider the activities that occur after a fail-secure operation occurs.
The options are to remain in a fail-secure state or to automatically reboot the system.
The fail-open state allows users to bypass failed security controls, erring on the side of permissiveness.