Alert - Microsoft Exchange zero-day vulnerabilities - Update 1

Number: AL22-011
Date: 30 September 2022
Updated: 9 November 2022

Audience

This Alert is intended for IT professionals and managers of notified organizations.

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.

Details

On 29 September 2022, Microsoft published an advisory confirming the existence of vulnerabilities impacting Microsoft ExchangeFootnote 1. First reported by GTSC Vietnam Technology ServicesFootnote 2, the vulnerabilities can only be exploited by an authenticated user. Microsoft reports that the first vulnerability identified as CVE-2022-41040, is a Server-Side Request Forgery (SSRF) vulnerability, while the second, identified as CVE-2022-41082, allows remote code execution (RCE) when PowerShell is accessible to the malicious actor.

GTSC has reported that these vulnerabilities have been exploited by malicious actors and has resulted in the deployment of webshells as well as information disclosure, command execution and lateral activity.

Update 1

On 8 November 2022, patches for CVE-2022-41040 Footnote 5 and CVE-2022-41082 Footnote 6 were released as part of the November 2022 Security Updates Footnote 7.

Recommended actions

Microsoft has reported that patches are in development but have confirmed that mitigation recommendations, such as those provided by GTSC, are successful in blocking the activity. Those recommendations are available within both the Microsoft and GTSC advisories Footnote 1Footnote 2Footnote 4.

As a result of incident response GTSC compiled several Indicators of Compromise (IOCs) to aid network defenders in the detection of malicious activity. The Cyber Centre recommends affected customers review the Cyber Centre joint cybersecurity advisory on technical approaches to uncovering and remediating malicious activity Footnote 3.

The Cyber Centre recommends Exchange customers continue to monitor Microsoft advisory spaces and update systems when a patch is made available.

Should activity matching the content of this Alert be discovered, recipients are encouraged to report via the My Cyber Portal, contact the Cyber Centre by email (contact@cyber.gc.ca), or by telephone (1-833-CYBER-88 or 1-833-292-3788).

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