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The Hacker News - Cybersecurity News and Analysis: ProxyShell

WARNING: Microsoft Exchange Under Attack With ProxyShell Flaws

WARNING: Microsoft Exchange Under Attack With ProxyShell Flaws

August 22, 2021Ravie Lakshmanan
The U.S. Cybersecurity and Infrastructure Security Agency is warning of active exploitation attempts that leverage the latest line of " ProxyShell " Microsoft Exchange vulnerabilities that were patched earlier this May, including deploying LockFile ransomware on compromised systems. Tracked as CVE-2021-34473, CVE-2021-34523, and CVE-2021-31207, the vulnerabilities enable adversaries to bypass ACL controls, elevate privileges on the Exchange PowerShell backend, effectively permitting the attacker to perform unauthenticated, remote code execution. While the former two were addressed by Microsoft on April 13, a patch for CVE-2021-31207 was shipped as part of the Windows maker's May Patch Tuesday updates. "An attacker exploiting these vulnerabilities could execute arbitrary code on a vulnerable machine," CISA  said . The development comes a little over a week after cybersecurity researchers sounded the alarm on  opportunistic scanning and exploitation  of unpat
Hackers Actively Searching for Unpatched Microsoft Exchange Servers

Hackers Actively Searching for Unpatched Microsoft Exchange Servers

August 13, 2021Ravie Lakshmanan
Threat actors are actively carrying out opportunistic  scanning  and  exploitation  of Exchange servers using a new exploit chain leveraging a trio of flaws affecting on-premises installations, making them the latest set of bugs after ProxyLogon vulnerabilities were exploited en masse at the start of the year. The remote code execution flaws have been collectively dubbed "ProxyShell." At least 30,000 machines are affected by the vulnerabilities,  according  to a Shodan scan performed by Jan Kopriva of SANS Internet Storm Center. "Started to see in the wild exploit attempts against our honeypot infrastructure for the Exchange ProxyShell vulnerabilities," NCC Group's Richard Warren  tweeted , noting that one of the intrusions resulted in the deployment of a "C# aspx webshell in the /aspnet_client/ directory." Patched in early March 2021,  ProxyLogon  is the moniker for CVE-2021-26855, a server-side request forgery vulnerability in Exchange Server tha
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