How to prevent ransomware attacks
By this time last year, 105 healthcare breaches had been reported to the U.S. Department of Health and Human Services (HHS) for a total of over 92 million lost records, compared with “only” 81 breaches and 3.5 million records so far in 2016. Good news, right? Well, sort of.
Unfortunately, this seemingly positive trend does not reflect the actual threat landscape in the healthcare industry. Ransomware is a type of malware that restricts access to files or systems with encryption until the victim (the hospital) pays the ransom for the key to unlock them.
As a former security operations lead for a hospital network, I responded to numerous ransomware infections following targeted phishing campaigns against the hospital. The incident response team followed the same procedure for each incident: isolate the infected PC and restore the corrupted (encrypted) files on the department shared drive from backup. In such isolated instances, there was no impact to clinical operations and patient care. However, the story would have been different in the case of widespread infection on the network.
There are many things that your healthcare organization should be doing to minimize the impact of successful ransomware attacks. Here are a few tips to get you started:
1. Develop and execute a plan for an end user awareness program
- Yes, I know it’s difficult to get approval to send regular hospital-wide security advisories, but smarter end users will surely result in fewer ransomware incidents.
2. Review and validate server backup processes
- Some organizations don’t realize their backups are compromised or were configured improperly until it’s too late. You may need them to restore service.
- Start with your file servers that host network shares for critical hospital departments
- Ensure you have backups that are not accessible by end users – ideally off-site. Backup administrator roles should be assigned sparingly, used sparingly and regularly audited.
- Test your backups regularly to validate they can be restored properly.
3. Review network drive permissions to minimize the impact that a single user can have
- Assign a project manager to organize an effort to evaluate permissions that users have on mapped network drives. Implement the principle of least privilege to minimize the impact that any single user can have on the organization’s network shared drives.
- This process could turn into a large, complex effort, so start with network drive locations used by critical departments (Emergency, Organ Transplant etc).
4. Conduct User Privilege Reviews
- Audit privileged roles used by the Server, Backup & Network Teams to validate appropriate access.
- Ensure administrators are assigned normal restricted accounts, separate from their highly privileged accounts.
- Require administrators to only use their highly privileged accounts when they need them.
- Remove automatic network drive mappings from administrative accounts, where possible.
- Restrict administrative accounts from receiving email.
5. Disable macro scripts from MS Office files using AD Group Policy
- According to Microsoft, 98 peercent of Office-targeted threats use macros. Disabling macro scripts from MS Office files will stop ransomware such as Locky.
- Office macros are usually not required for the majority of PCs used in healthcare environments. Enable macros for exceptions or certain departments only.
6. Review your monthly patch management processes
- Many hospitals struggle to patch their systems within 30 days of Microsoft’s “Patch Tuesday” monthly patch release.
- Review your patching processes and look for opportunities to remove roadblocks.
- Consider deploying an advanced endpoint product that prevents exploits due to missing patches and malware.
7. Evaluate your inbound spam and malware protection
- Ensure you are configured to block inbound mail as per recommendations from your email server vendor (i.e. block executables in attachments etc)
8. Deploy a next-generation firewall to protect the hospital network
- Ensure your firewall automatically blocks known threats based on a threat feed that constantly updates.
- Ensure your firewall provides sandboxing capabilities so you can stop unknown threats (URLs and executables) before they reach the endpoint. Sandboxing is the best way to detect new variants of ransomware that constantly appearing in the wild.
- Configure your firewall/proxy to require user interaction for hospital end users communicating with websites uncategorized by the network proxy or firewall (i.e. click a “proceed” button). Many uncategorized websites are used in targeted phishing campaigns to distribute malware.
9. Deploy advanced endpoint protection to protect the endpoint
- Traditional antivirus is not effective anymore against advanced malware like ransomware which continuously changes to avoid detection. Your endpoints need advanced protection capable of stopping processes that exhibit malicious behavior, rather than checking for individual known bad files.
- Whitelisting can work for some organizations but most hospitals need to permit hundreds of applications across their departments so it is often difficult for IT to manage the list. Behavior-based malware detection tends to be very effective, and also lightweight on the endpoint.
These suggestions range from low-tech to high-tech and vary in cost, but all contribute to create a hospital environment that is highly resistant to ransomware with the least amount of manual management. Decide for yourself which combination of mitigating activities is best for your environment.