Last week, the CERT Coordination Center (CERT/CC) issued a vulnerability note warning versions of Microsoft Exchange 2013 and newer are vulnerable to an NTLM relay attack that allows for attackers to gain domain admin privileges. Organizations that rely on Microsoft Exchange are currently at risk of a serious data breach. This attack is particularly concerning given that it obtains privileges to the domain controller, which is essentially the “keys to the kingdom.” We’ve simplified some of the specifics of this attack for the purposes of this blog, but for a full technical breakdown, please see research from Dirk-jan Mollema.
Late last year, we began conversations with the Tuck School of Business at Dartmouth College about their current security concerns. Like many organizations, a portion of their workloads are moving from on-premises to the cloud. One of the big concerns about moving to the cloud is how to secure infrastructure as companies currently do from within the defined perimeter of their internal network. They also needed to provide added security without heavily impacting the end user (students, faculty, and staff) experience. Because these are common concerns for many other organizations, I’d like to share how we helped this customer overcome these security concerns.
In March Patch Tuesday, Microsoft released a patch for CVE-2018-0886, a critical vulnerability that was discovered by Preempt. This vulnerability can be classified as a logical remote code execution (RCE) vulnerability. It resembles a classic relay attack, but with a nice twist: It is related to RSA cryptography (and prime numbers) which makes it quite unique and interesting.
In March Patch Tuesday, Microsoft released a patch for CVE-2018-0886, a vulnerability discovered by Preempt researchers. The vulnerability consists of a logical flaw in Credential Security Support Provider protocol (CredSSP) which is used by RDP (Remote Desktop Protocol) and Windows Remote Management (WinRM) that takes care of securely forwarding credentials to target servers. The vulnerability can be exploited by attackers by employing a man-in-the-middle attack to achieve the ability to run code remotely on previously not infected machines in the attacked network. The vulnerability, in many real-world scenarios where victim network has vulnerable network equipment, could result in an attacker gaining the ability to move laterally in the victim’s network and even infect domain controller with malicious software. No attacks have been detected in the wild by Preempt.
Authors: Roman Blachman, Yaron Zinar.
We recently reviewed a customer’s network and found that 85%(!) of all users in the network had some unnecessary administrative privilege. The excessive privilege stemmed from an indirect inclusion in a protected admin group. Most Active Directory audit systems easily alert on excessive privileges, but will often miss users who have elevated domain privileges directly through domain discretionary access control list (DACL) configuration. We refer to these users as stealthy admins.
Over the past few months, the Preempt research team discovered and reported two Microsoft NT LAN Manager (NTLM) vulnerabilities. These vulnerabilities have a common theme around two different protocols handling NTLM improperly. These issues are particularly significant as they can potentially allow an attacker to create new domain administrator accounts even when best-practice controls such as LDAP server signing and RDP restricted admin mode are enabled.