Microsoft urges Exchange admins to patch their on-prem servers now
Given the bug’s severity, Microsoft say patch now
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Microsofthas issued an urgent security update to patch a high severity vulnerability that affects multiple editions of their popularhosted email serverMicrosoft Exchange, and could be exploited to remotely execute code on vulnerable servers.
According to Microsoft, the security flaw, tracked as CVE-2021-42321, is caused by improper validation ofcmdletarguments.
“We are aware of limited targeted attacks in the wild using one of [the] vulnerabilities (CVE-2021-42321), which is a post-authentication vulnerability in Exchange 2016 and 2019. Our recommendation is to install these updates immediately to protect your environment,”sharesMicrosoft.
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It goes on to add that the bug only impacts on-premise Microsoft Exchange servers, including those used by customers in Exchange Hybrid mode. Users of the Exchange Online service are already protected against exploitation attempts, and can safely ignore the advisory.
Patch immediately
Reporting on the development,BleepingComputernotesthat Microsoft Exchange has been at the receiving end of two major campaigns, which have targeted different, but related vulnerabilities known as ProxyLogon and ProxyShell.
ProxyLogonwas first exploited by state-sponsored threat actors back in March to deploycryptominers,ransomware, and othermalware. Then in August, attackers once again were quick to capitalize after security researchers managed to demonstrate a working exploit that consisted of three chained vulnerabilities in Exchange collectively referred to asProxyShell.
Both issues have since been addressed, but the new vulnerability has once again given threat actors an opportunity to remotely attack unpatched servers, which would explain the urgency in Microsoft’s appeal to get admins to update their vulnerable installations without delay.
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With almost two decades of writing and reporting on Linux, Mayank Sharma would like everyone to think he’sTechRadar Pro’sexpert on the topic. Of course, he’s just as interested in other computing topics, particularly cybersecurity, cloud, containers, and coding.
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