Number: AL19-001
Date: 10 January 2019
Purpose
An ALERT is used to raise awareness of a recently identified cyber threat that may impact cyber information assets, and to provide additional detection and mitigation advice to recipients. (The Canadian Centre for Cyber Security ("Cyber Centre") is also available to provide additional assistance regarding the content of this ALERT to recipients as requested.)
Assessment
The goal of this Alert is to bring heightened attention to two vulnerabilities in Microsoft products for which there are currently patches available. The first vulnerability is CVE-2019-0547 – Windows DHCP Client Remote Code Execution Vulnerability. This vulnerability in the DHCP client could allow attackers to execute code on affected systems by sending a specially crafted DHCP responses to a client. Code execution through a widely available listening service, such as DHCP, means this is a wormable vulnerability. Microsoft has listed this patch as «Critical».
The second vulnerability is CVE-2019-0586 – Microsoft Exchange Memory Corruption Vulnerability. This vulnerability in Exchange could allow an attacker to take control of an Exchange server just by sending it a specially crafted email. Microsoft has listed this patch as «Important», however the Cyber Centre assesses this as a Critical patch.
CVE references: CVE-2019-0547, CVE-2019-0586
Suggested action
- The Cyber Centre recommends that organizations deploy Microsoft patches as soon as possible.
- Where immediate full patch deployment is not possible, special attention should be given to the two patches listed in the References section.
- A mail filtering gateway should be in place to prevent malicious emails from reaching the Exchange server.
References
Microsoft Security Bulletins:
https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2019-0586
https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2019-0547
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.