CSSA ICS/SCADA Security Architect preparation cheat sheet

Map assets and communication to actual physical functions and consequences.

A hierarchy diagram does not enforce a security boundary.

DMZs, proxies, firewalls and one-way gateways have different roles.

Fail-closed communication is not automatically a safe process state.

Combine observed traffic with drawings, records and process knowledge.

Prioritize remediation by actual exposure and consequences, not one score alone.

Remote access and engineering changes need bounded authority and records.

Coordinate containment and recovery with actual process safety and verified dependencies.

Internet-facing services belong in a DMZ; data stores sit in a filtered internal zone.

VLANs alone are not a trust boundary - add DAI, private VLANs and 802.1 X.

IPsec AH gives integrity only; ESP adds confidentiality.

IDS is passive and alerts; IPS is inline and blocks.

NAT is not a security control and temporary rules must be removed.

Identification, authentication, authorisation and accounting are four distinct steps.

MFA needs two different factor categories, not two instances of one.

RBAC suits stable job roles; ABAC suits context-dependent, fine-grained rules.

Kerberos uses a KDC with TGT and service tickets for SSO.

Symmetric ciphers handle bulk data; asymmetric ciphers solve key distribution and signatures.

Signing uses a specified signature scheme with the signer’s private key; verification and custody are essential to origin evidence.

ECB leaks patterns; use authenticated modes such as GCM or encrypt-then-MAC.

Risk assessment cycles through identification, analysis, and evaluation, producing a maintained risk register

Single loss expectancy = asset value x exposure factor; annualized loss expectancy = SLE x annualized rate of occurrence

Risk requires a threat, a vulnerability, and an impact; none alone is sufficient

Inherent risk is before controls, residual risk after them - always state which is being scored

Control effectiveness and uncertainty affect any expected-loss comparison.

Distinguish tolerated data loss from tolerated interruption.

A recovery point and restore time must both meet the stated targets.

A same-failure-domain snapshot alone does not cover loss of that domain.

Verify complete restore procedures and actual dependency behavior.