Alert - Critical Microsoft Remote Desktop Vulnerability

Number: AL19-009
Date: 14 May 2019

PURPOSE

An Alert is used to raise awareness of a recently disclosed Remote Code Execution vulnerability in the Microsoft Remote Desktop Services platform.

ASSESSMENT

Microsoft has released patches for a critical vulnerability in Microsoft Remote Desktop Services (RDS). The vulnerability allows a remote, unauthenticated actor to run arbitrary code on some Microsoft operating systems running RDS. This vulnerability is ‘wormable’, meaning that exploits of this vulnerability could automatically propagate from one vulnerable system to another.

The vulnerable operating systems are:

  • Windows 7 for 32-bit Systems Service Pack 1
  • Windows 7 for x64-based Systems Service Pack 1
  • Windows Server 2008 for 32-bit Systems Service Pack 2
  • Windows Server 2008 for 32-bit Systems Service Pack 2
  • Windows Server 2008 for Itanium-Based Systems Service Pack 2
  • Windows Server 2008 for x64-based Systems Service Pack 2
  • Windows Server 2008 for x64-based Systems Service Pack 2 (Server Core installation)
  • Windows Server 2008 R2 for Itanium-Based Systems Service Pack 1
  • Windows Server 2008 R2 for x64-based Systems Service Pack 1
  • Windows Server 2008 R2 for x64-based Systems Service Pack 1 (Server Core installation)
  • Windows XP SP3 x86
  • Windows XP Professional x64 Edition SP2
  • Windows XP Embedded SP3 x86
  • Windows Server 2003 SP2 x86
  • Windows Server 2003 x64 Edition SP2

SUGGESTED ACTION

  • Install the latest updates for the vulnerable operating systems.
  • Disable Remote Desktop Services if not required. If required, closely monitor network traffic and the logs of any vulnerable systems for suspicious activity.
  • Enable Network Level Authentication (NLA) on systems running Windows 7, Windows Server 2008, and Windows Server 2008 R2. This is a partial mitigation which will prevent the spread of the malware.
  • Block TCP port 3389 on the firewall, if possible. This will prevent unauthorized access from the Internet.

REFERENCES

Microsoft advisory: https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2019-0708

Microsoft advisory for legacy operating systems (Windows XP and Server 2003): https://support.microsoft.com/en-ca/help/4500705/customer-guidance-for-cve-2019-0708

Microsoft blog post: https://blogs.technet.microsoft.com/msrc/2019/05/14/prevent-a-worm-by-updating-remote-desktop-services-cve-2019-0708/

NOTE TO READERS

The Canadian Centre for Cyber Security (Cyber Centre) operates as part of the Communications Security Establishment.  We are Canada's national authority on cyber security and we lead the government's response to cyber security events. As Canada's national computer security incident response team, the
Cyber Centre works in close collaboration with government departments, critical infrastructure, Canadian businesses and international partners to prepare for, respond to, mitigate, and recover from cyber events. We do this by providing authoritative advice and support, and coordinating information
sharing and incident response. The Cyber Centre is outward-facing, welcoming partnerships that help build a stronger, more resilient cyber space in Canada.

 

 

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