The Essential Eight
While no single mitigation strategy is guaranteed to prevent cyber security incidents, organisations are recommended to implement eight essential mitigation strategies as a baseline. This baseline, known as the Essential Eight, makes it much harder for adversaries to compromise systems. Furthermore, implementing the Essential Eight proactively can be more cost-effective in terms of time, money and effort than having to respond to a large-scale cyber security incident.
There is a suggested implementation order for each adversary to assist organisations in building a strong cyber security posture for their systems. Once organisations have implemented their desired mitigation strategies to an initial level, they should focus on increasing the maturity of their implementation such that they eventually reach full alignment with the intent of each mitigation strategy.
Mitigation Strategies to Prevent Malware Delivery and Execution
Application whitelisting of approved/trusted programs to prevent the execution of unapproved/malicious programs including .exe, DLL, scripts (e.g. Windows Script Host, PowerShell and HTA) and installers.
Why: All non-approved applications (including malicious code) are prevented from executing.
Patch applications e.g. Flash, web browsers, Microsoft Office, Java and PDF viewers. Patch/mitigate computers with ‘extreme risk’ vulnerabilities within 48 hours. Use the latest version of applications.
Why: Security vulnerabilities in applications can be used to execute malicious code on systems.
Configure Microsoft Office macro settings to block macros from the Internet, and only allow vetted macros either in ‘trusted locations’ with limited write access or digitally signed with a trusted certificate.
Why: Microsoft Office macros can be used to deliver and execute malicious code on systems.
User application hardening. Configure web browsers to block Flash (ideally uninstall it), ads and Java on the Internet. Disable unneeded features in Microsoft Office (e.g. OLE), web browsers and PDF viewers.
Why: Flash, ads and Java are popular ways to deliver and execute malicious code on systems.
Mitigation Strategies to Limit the Extent of Cyber Security Incidents
Restrict administrative privileges to operating systems and applications based on user duties. Regularly revalidate the need for privileges. Don’t use privileged accounts for reading email and web browsing.
Why: Admin accounts are the ‘keys to the kingdom’. Adversaries use these accounts to gain full access to information and systems.
Patch operating systems. Patch/mitigate computers (including network devices) with ‘extreme risk’ vulnerabilities within 48 hours. Use the latest operating system version. Don't use unsupported versions.
Why: Security vulnerabilities in operating systems can be used to further the compromise of systems.
Multi-factor authentication including for VPNs, RDP, SSH and other remote access, and for all users when they perform a privileged action or access an important (sensitive/high-availability) data repository.
Why: Stronger user authentication makes it harder for adversaries to access sensitive information and systems.
Mitigation Strategies to Recover Data and System Availability
Daily backups of important new/changed data, software and configuration settings, stored disconnected, retained for at least three months. Test restoration initially, annually and when IT infrastructure changes.
Why: To ensure information can be accessed following a cyber security incident (e.g. a ransomware incident).
The 3-2-1 Backup Rule
The 3-2-1 backup rule is an easy-to-remember acronym for a common approach to keeping your data safe in almost any failure scenario. The rule is: keep at least three (3) copies of your data, and store two (2) backup copies on different storage media, with one (1) of them located offsite
Store two backup copies on different devices or storage media
We must remember that any storage device will fail sooner or later. Hard drives fail over time, whether because of a defect or simply wearing out. Two devices of the same type have a much greater risk of failing around the same time than two devices of different types or two different storage media. Thus, the 3-2-1 backup rule says that if you keep your primary data on an internal hard drive, store your backup copies a different way – for example, using an external hard drive, optical disks, digital tape, or the cloud.
Keep at least one backup copy offsite
As it is obvious that a local disaster can damage all copies of data stored in one place, the 3-2-1 backup rule says: keep at least one copy of your data in a remote location, such as offsite storage or the cloud. If you want to protect your data from disasters, which might strike large areas, “remote” should mean as far away as possible, i.e., in another city, state, country, or even continent.
While storing one backup copy offsite strengthens your data security, having another backup copy onsite provides for faster and simpler recovery in case of failure.