Hardening: The US National Institute of Standards and Technology has published a guide to whitelisting that can help organisations deploy one of the most important defensive security technologies.

Application whitelisting is chief among the Australian Signals Directorate's much-lauded Top 4 Strategies to Mitigate Targeted Cyber Intrusions for its ability to drastically reduce attack surfaces and help identify and block suspicious executables.

Skip spies say when done right application whitelisting is an "incredibly effective" way to ensure defence, stability and consistency, but is often borked in organisations such that it offers only a impression of security.

To that end the technology is not merely a portal through which only approved applications can be installed nor is it just a block on users writing to local drives.

Now the NIST has offered more application whitelisting fodder to complement the words NIST's Guide to Application Whitelisting [pdf] that it hopes to help organisations with the basics of the premise along with implementation support.

The agency's senior advisor Adam Sedgewick and computer scientist Murugiah Souppaya authored the guide with Scarfone Cybersecurity scribe Karen Scarfone.

"An application whitelist is a list of applications and application components that are authorised to be present or active on a host according to a well-defined baseline," the trio write.

"If design decisions are incorrect, then the application whitelisting implementation will be more susceptible to compromise and failure."

The team quickly illustrates five points deploying an effective application whitelist including first evaluating built in operating system capabilities, using sophisticated whitelisting attributes unless strict access controls are in place, and testing deployments in monitoring mode prior to roll out.

Risk assessments should be the first order of business however since application whitelisting is a functionality pain.

"An application whitelisting technology might be considered unsuitable if, for instance, it had to be disabled in order to install security updates for the operating system or particular applications," the team says.

"A combination of digital signature and publisher and cryptographic hash techniques generally provides the most accurate and comprehensive application whitelisting capability, but usability and maintainability requirements can put significant burdens on the organisation."

Roll outs should be phased using clear processes that will help minimise pitfalls, NIST adds. ®