New Mitigation for Microsoft Exchange Zero Day Vulnerability
In today’s SensCy Cyber Alert, your SensCy team urges Microsoft Exchange Servers users to review the new remediation tips for TWO zero-day vulnerabilities. The vulnerabilities are tracked by the National Institute of Standards and Technology as CVE-2022-41040 and CVE-2022-41082. The vulnerabilities impact Exchange Server 2013, 2016, and 2019 based on the reports of in-the-wild exploitation.
Microsoft workaround:
Microsoft recommends user to add a blocking rule in IIS Manager as a temporary workaround.
Here is how to add the blocking rule:
- Microsoft has since revised the URL Rewrite rule (also available as a standalone PowerShell script) to take this into account –
- Open IIS Manager
- Select Default Web Site
- In the Feature View, click URL Rewrite
- In the Actions pane on the right-hand side, click Add Rule(s)…
- Select Request Blocking and click OK
- Add the string “.*autodiscover\.json.*Powershell.*” (excluding quotes)
- Select Regular Expression under Using
- Select Abort Request under How to block and then click OK
- Expand the rule and select the rule with the pattern: .*autodiscover\.json.*Powershell.* and click Edit under Conditions
- Change the Condition input from {URL} to {REQUEST_URI}
Please reach out to SensCy for any additional questions or concerns.