Security News > 2021 > August > Hackers now backdoor Microsoft Exchange using ProxyShell exploits

Threat actors are actively exploiting Microsoft Exchange servers using the ProxyShell vulnerability to install backdoors for later access.

ProxyShell is the name of an attack that uses three chained Microsoft Exchange vulnerabilities to perform unauthenticated, remote code execution.

Last week, Orange Tsai gave a Black Hat talk about recent Microsoft Exchange vulnerabilities he discovered when targeting the Microsoft Exchange Client Access Service attack surface.

Security researcher Kevin Beaumont began seeing threat actors scan for Microsoft Exchange servers vulnerable to ProxyShell.

Today, Beaumont and NCC Group's vulnerability researcher Rich Warren disclosed that threat actors have exploited their Microsoft Exchange honeypots using the ProxyShell vulnerability.

Last week, Jang explained to BleepingComputer that 265KB is the minimum files size that can be created using the ProxyShell exploit due to its abuse of the Mailbox Export function of Exchange Powershell to create PST files.

News URL

https://www.bleepingcomputer.com/news/microsoft/hackers-now-backdoor-microsoft-exchange-using-proxyshell-exploits/