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Jun 25, 20212 min read

How to Protect Active Directory Against Ransomware Attacks

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Ransomware attacks every type of organization from every angle and Active Directory remains the common target. Stop privilege escalation by fixing these key AD and group policy misconfigurations.


Ransomware has struck every type of organization around the world. It's changed dramatically, too, entering the enterprise from nearly every angle, with attackers leveraging stolen data by posting it on the internet to force victims to pay. In most cases (see SolarWinds and XingLocker), Active Directory (AD) is targeted so the attacker can easily distribute the ransomware after obtaining domain privileges. There are, however, ways to help secure Active Directory to prevent ransomware from succeeding.


Distinct areas within Active Directory can be secured, which will increase the overall security of the enterprise and reduce the security risk at the same time. Specifically, the following settings around AD objects can be secured. Here's how:

  • Misconfigurations of user attributes need to be fixed

  • Misconfigurations of groups need to be fixed

  • Privileged groups need to be cleaned up

  • AD processes need to have correct configurations (e.g. SDProp)

  • Service principal names (SPNs) need to be secured (shown in Figure 1)

  • Trust relationships need to be correct and secured

  • SidHistory attribute needs to be cleaned up for users


Figure 1. User account with Service Principal Name (SPN).

In addition, AD itself and group policy can be secured to ensure the attacker can't leverage misconfigurations and areas where privilege escalation can be achieved. Here's how:

  • AD trusts need to be verified and secured (shown in Figure 2)

  • AD delegations need to be cleaned up

  • Group policy delegations need to be cleaned up

  • Group policy structural components need to be secured

  • Security settings deployed by group policy objects need to be enabled


Figure 2. Mergers and acquisitions can orphan trusts; in addition, required trusts need to be secured.

Finally, attackers want to gain privileges. Once privileges are obtained, they want to create backdoors. Being able to detect these types of AD attacks is essential. Below are some of the actions AD admins and security pros can take to disrupt attack paths:

  • Ensure privileged group membership is monitored

  • Detect DCShadow and DCSync attack

  • Golden Ticket attacks (illustrated in Figure 3)

  • Detect lateral movement attacks

  • Detect dangerous SIDHistory and PrimaryGroupID settings


Figure 3. Tenable.ad can detect advanced attacks on Active Directory, in real time, with no agent or privilege.

Summary

Technology is available to continuously and automatically analyse and detect AD security and attack paths. Contact Satisnet today to find out more about Tenable.ad!



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