Top 4 Mitigation Strategies to Protect Your ICT System
Download ACSC Protect: Top 4 Mitigation Strategies to Protect Your ICT System (PDF), updated November 2012
First published 2011; updated November 2012
- Targeted cyber intrusions remain the biggest threat to government ICT systems. Since opening in early 2010, the Cyber Security Operations Centre (CSOC) has detected and responded to thousands of these intrusions.
- You should never assume that your information is of little or no value. Adversaries are not just looking for classified information. A lot of activity observed by the CSOC has an economic focus, looking for information about Australia’s business dealings, its intellectual property, its scientific data and the government’s intentions.
- The threat is real, but there are things every organisation can do to significantly reduce the risk of a cyber intrusion. In 2009, based on our analysis of these intrusions, the Australian Signals Directorate (ASD) produced Strategies to Mitigate Targeted Cyber Intrusions – a document that lists a variety of ways to protect an organisation’s ICT systems. At least 85% of the intrusions that ASD responded to in 2011 involved adversaries using unsophisticated techniques that would have been mitigated by implementing the Top 4 mitigation strategies as a package.
- The Top 4 mitigations are application whitelisting, patching applications and operating systems and using the latest versions, and minimising administrative privileges. This document is designed to help senior managers in organisations understand the effectiveness of implementing these strategies.
- Whitelisting – when implemented correctly – makes it harder for an adversary to compromise an organisation’s ICT system. Application whitelisting is a technical measure which only allows specifically authorised applications to run on a system. This helps prevent malicious software and unauthorised applications running.
- A software patch is a small piece of software designed to fix problems or update a computer program. Patching an organisation’s system encompasses both the second and third mitigation strategies. It is important to patch both your operating system and applications within a two-day timeframe for serious vulnerabilities. Once a vulnerability in an operating system or application is made public you can expect malware to be developed by adversaries within 48 hours. In some cases, malware has been developed to take advantage of a publicly-disclosed vulnerability within eight hours.
- There is often a perception that by patching a system without rigorous testing, something is likely to break on the system. In the majority of cases, patching will not affect the function of an organisation’s ICT system. Balancing the risk between taking weeks to test patches and patching serious vulnerabilities within a two-day timeframe can be the difference between a compromised and a protected system.
Restricting administrative privileges
- When an adversary targets a system, they will primarily look for user accounts with administrative privileges. Administrators are targeted because they have a high level of access to the organisation’s ICT system. If an adversary gains access to a user account with administrative privileges they can access any data the administrator can access – which generally means everything. Minimising administrative privileges makes it more difficult for the adversary to spread or hide their existence on a system.
- Administrative privileges should be tightly controlled. It is important that only staff and contractors that need administrative privileges have them. In these cases, separate accounts with administrative privileges should be created which do not have access to the internet. This reduces the likelihood of malware infecting the administrator as they should not be web browsing or checking emails while using their privileged account.
Creating a defence-in-depth system
- As a package, the Top 4 mitigation strategies are highly effective in helping achieve a defence-in-depth ICT system. The combination of all four strategies, correctly implemented, will help protect an organisation from low to moderately sophisticated intrusion attempts. Put simply, they will make it significantly more difficult for an adversary to get malicious code to run on your ICT system, or continue to run undetected. This is because the Top 4 strategies enable multiple lines of defence against cyber intrusions.
- Of course, implementing the other strategies will provide additional protection for your ICT system. Several strategies have an overall security rating of ‘excellent’ which means that they are the most effective measures to protect ICT systems. However, an organisation should also conduct a risk assessment and implement other mitigation strategies as required to protect its ICT system. The 35 strategies are designed to be flexible to meet the needs of different organisations, allowing every organisation to assess the risk to its information and act accordingly.
- The full list of strategies and accompanying documents is available at ACSC’s Strategies to Mitigate Targeted Cyber Intrusions.
- Organisations or individuals with questions regarding this advice can contact the ACSC by emailing firstname.lastname@example.org or calling 1300 CYBER1 (1300 292 371).