Microsoft Issues Improved Mitigations for Unpatched Exchange Server Vulnerabilities

Microsoft on Friday disclosed it has produced far more improvements to the mitigation method presented as a signifies to protect against exploitation makes an attempt from the newly disclosed unpatched security flaws in Exchange Server.

To that close, the tech large has revised the blocking rule in IIS Supervisor from “.*autodiscover.json.*Powershell.*” to “(?=.*autodiscover.json)(?=.*powershell).”

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The list of up to date actions to include the URL Rewrite rule is below –

• Open up IIS Manager
• Pick out Default Web Site
• In the Element Watch, simply click URL Rewrite
• In the Steps pane on the ideal-hand aspect, click Add Rule(s)…
• Find Ask for Blocking and click Alright
• Incorporate the string “(?=.*autodiscover.json)(?=.*powershell)” (excluding quotes)
• Pick out Normal Expression beneath Working with
• Decide on Abort Ask for underneath How to block and then click on Ok
• Increase the rule and find the rule with the sample: (?=.*autodiscover.json)(?=.*powershell) and click Edit less than Problems
• Modify the Issue enter from URL to UrlDecode:Request_URI and then click on Okay

Alternatively, people can accomplish the desired protections by executing a PowerShell-dependent Exchange On-premises Mitigation Device (EOMTv2.ps1), which has also been current to acquire into account the aforementioned URL pattern.

The actively-exploited issues, known as ProxyNotShell (CVE-2022-41040 and CVE-2022-41082), are nevertheless to be addressed by Microsoft, though with Patch Tuesday correct all-around the corner, the wait around may possibly not be for lengthy.

Prosperous weaponization of the flaws could enable an authenticated attacker to chain the two vulnerabilities to obtain distant code execution on the fundamental server.

The tech large, final 7 days, acknowledged that the shortcomings may well have been abused by a solitary state-sponsored menace actor because August 2022 in constrained specific attacks aimed at fewer than 10 corporations globally.

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