Microsoft has issued an pressing safety replace to patch a excessive severity vulnerability that impacts a number of editions of their well-liked hosted email server Microsoft Exchange, and might be exploited to remotely execute code on susceptible servers.
According to Microsoft, the safety flaw, tracked as CVE-2021-42321, is attributable to improper validation of cmdlet arguments.
“We are conscious of restricted focused assaults within the wild utilizing considered one of [the] vulnerabilities (CVE-2021-42321), which is a post-authentication vulnerability in Exchange 2016 and 2019. Our advice is to set up these updates instantly to shield your setting,” shares Microsoft.
It goes on to add that the bug solely impacts on-premise Microsoft Exchange servers, together with these utilized by clients in Exchange Hybrid mode. Users of the Exchange Online service are already protected in opposition to exploitation makes an attempt, and might safely ignore the advisory.
Reporting on the event, BleepingComputer notes that Microsoft Exchange has been on the receiving finish of two main campaigns, which have focused totally different, however associated vulnerabilities generally known as ProxyLogon and ProxyShell.
ProxyLogon was first exploited by state-sponsored menace actors again in March to deploy cryptominers, ransomware, and different malware. Then in August, attackers as soon as once more had been fast to capitalize after safety researchers managed to show a working exploit that consisted of three chained vulnerabilities in Exchange collectively referred to as ProxyShell.
Both points have since been addressed, however the brand new vulnerability has as soon as once more given menace actors a possibility to remotely assault unpatched servers, which might clarify the urgency in Microsoft’s attraction to get admins to replace their susceptible installations directly.
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https://www.techradar.com/information/microsoft-urges-exchange-admins-to-patch-their-on-prem-servers-now
