Microsoft Exchange servers are once again under attack
Patch your servers now, urge security researchers
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Threat actors have once again started scanning for the now-patched vulnerabilities inMicrosoft Exchange, cybersecurity experts shared at the recent Black Hat 2021 conference.
The attack was revealed by security researcher Kevin Beaumont,who tweetedthat a threat actor was probing hisMicrosoftExchange honeypot against the server’sAutodiscoverservice.
While these initial attempts were unsuccessful,Beaumont later noticedthat the attacker modified their attack strategy in accordance with new details shared during a Black Hat presentation by Devcore’s principal security researcher Orange Tsai.
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Tsai is credited for discovering three vulnerabilities in the Microsoft Exchange earlier this year. Collectively known as ProxyShell, the vulnerabilities could be chained to perform unauthenticated, remote code execution on Microsoft Exchange servers.
New attack vector
Presenting a talk on ProxyShell at the conference, Tsai explained that one of the components of the ProxyShell attack chain targets the Microsoft ExchangeAutodiscoverservice.
After watching Tsai’s talk, security researchers PeterJson and Jangpublished an articleproviding technical information about how they could successfully reproduce the ProxyShell exploit, which has apparently taught a few new tricks to the threat actors.
Armed with the new details,it appearsthat the threat actors were successfully able to detect a vulnerable system.
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While the ProxyShell vulnerabilities have been patched, Tsai states that there are currently 400,000 Microsoft Exchange servers exposed on the Internet, andBeaumont believesthat about 50% of these haven’t yet been patched leaving them exposed and discoverable by this new strategy.
ViaBleepingComputer
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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