Threat Signal Report

Possible New Microsoft Exchange RCE 0-day Being Exploited in the Wild

description-logo Description

UPDATE September 30th 2022: Updated for CVE numbers assigned to the vulnerabilities and a blog Microsoft published on the vulnerabilities.


Note: This is a breaking news event. All information and updates related to this event will be updated once relevant information is available.

FortiGuard Labs is aware of reports that an unpatched Microsoft Exchange vulnerability is being exploited in the wild. It is a Remote Command Execution (RCE) vulnerability, as such successful exploitation could allow an attacker to execute remote commands on affected Microsoft Exchange servers. At the time of this writing, patches and CVE assignments are not available.


Microsoft released a blog on September 29, 2022, for the RCE vulnerability as well as a new Server-Side Request Forgery (SSRF) vulnerability that was used in chain with the RCE vulnerability. CVE-2022-41082 has been assigned to the RCE vulnerability. CVE-2022-41040 bas been assigned to the other vulnerability.


Why is this Significant?

This is significant because this is likely a new unpatched Remote Command Execution (RCE vulnerability). Successful exploitation could allow an attacker to execute remote commands on affected Microsoft Exchange servers. Microsoft Exchange is widely used in Enterprise and an unpatched vulnerability poses a serious threat to many organizations worldwide.


When was the Vulnerability Discovered?

On September 28, 2022, GTSC (security vendor) published a blog on an unpatched Microsoft Exchange vulnerability which was leveraged in an attack against an unnamed critical infrastructure.


Which Versions of Microsoft Exchange do the Vulnerabilities Affect?

The vulnerabilities affect the following Microsoft Exchange versions:


  • Microsoft Exchange Server 2013
  • Microsoft Exchange Server 2016
  • Microsoft Exchange Server 2019


Has Microsoft Released a Patch for the Vulnerability?

At the time of this writing (September 29, 2022), Microsoft has not released a patch for the vulnerability.


Has the Vendor Released an Advisory for the Vulnerability?

Microsoft released a blog on the vulnerabilities. See the Appendix for a link to "Customer Guidance for Reported Zero-day Vulnerabilities in Microsoft Exchange Server".


What is the Status of Coverage?

FortiGuard Labs has the following IPS signature in place for the potential zero day vulnerability in Microsoft Exchange:


  • MS.Exchange.Server.Autodiscover.Remote.Code.Execution


All network IOCs on the GTSC blog are blocked by the WebFiltering client.



What Mitigation Steps are Available?

Microsoft provided the mitigation information in their blog. For details, see the Appendix for a link to "Customer Guidance for Reported Zero-day Vulnerabilities in Microsoft Exchange Server".


GTSC provided potential detection and mitigation information in their blog. Note that those detection and mitigation have not been verified by FortiGuard Labs. For additional information, see the Appendix for a link to "WARNING: NEW ATTACK CAMPAIGN UTILIZED A NEW 0-DAY RCE VULNERABILITY ON MICROSOFT EXCHANGE SERVER".


Definitions

Traffic Light Protocol

Color When Should it Be used? How may it be shared?

TLP: RED

Not for disclosure, restricted to participants only.
Sources may use TLP:RED when information cannot be effectively acted upon by additional parties, and could lead to impacts on a party's privacy, reputation, or operations if misused. Recipients may not share TLP:RED information with any parties outside of the specific exchange, meeting, or conversation in which it was originally disclosed. In the context of a meeting, for example, TLP:RED information is limited to those present at the meeting. In most circumstances, TLP:RED should be exchanged verbally or in person.

TLP: AMBER

Limited disclosure, restricted to participants’ organizations.
Sources may use TLP:AMBER when information requires support to be effectively acted upon, yet carries risks to privacy, reputation, or operations if shared outside of the organizations involved. Recipients may only share TLP:AMBER information with members of their own organization, and with clients or customers who need to know the information to protect themselves or prevent further harm. Sources are at liberty to specify additional intended limits of the sharing: these must be adhered to.

TLP: GREEN

Limited disclosure, restricted to the community.
Sources may use TLP:GREEN when information is useful for the awareness of all participating organizations as well as with peers within the broader community or sector. Recipients may share TLP:GREEN information with peers and partner organizations within their sector or community, but not via publicly accessible channels. Information in this category can be circulated widely within a particular community. TLP:GREEN information may not be released outside of the community.

TLP: WHITE

Disclosure is not limited.
Sources may use TLP:WHITE when information carries minimal or no foreseeable risk of misuse, in accordance with applicable rules and procedures for public release. Subject to standard copyright rules, TLP:WHITE information may be distributed without restriction.