From Public Key to Exploitation: How We Exploited the Authentication in MS-RDP

Posted by Eyal Karni on Mar 13, 2018 10:05:15 AM

 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.

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Topics: Microsoft, Security Advisory, Black Hat, Hacking, kerberos, RDP, Multi-factor Authentication

Security Advisory: Critical Vulnerability in CredSSP Allows Remote Code Execution on Servers Through MS-RDP (Video)

Posted by Yaron Zinar on Mar 13, 2018 10:03:36 AM

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.

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Topics: kerberos, Threat Detection, Security Advisory, Microsoft, CredSSP, Hacking

Advisory: Flaw in Azure AD Connect Software Can Allow Stealthy Admins to Gain Full Domain Control

Posted by Roman Blachman on Dec 12, 2017 9:42:26 AM

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.

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Topics: Stealthy Admin, Credential Compromise, Azure AD Connect, Microsoft, Security Advisory

New LDAP & RDP Relay Vulnerabilities in NTLM

Posted by Yaron Zinar on Jul 11, 2017 10:01:54 AM

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.

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Topics: NTLM, Domain Controller, Threat Detection, Hacking, Microsoft, Security Advisory