Pierluigi Paganini November 20, 2022

Proof-of-concept exploit code for two actively exploited Microsoft Exchange ProxyNotShell flaws released online.

Proof-of-concept exploit code has been released online for two actively exploited vulnerabilities in Microsoft Exchange, known as ProxyNotShell.

The two flaws are:

• CVE-2022-41040 – Microsoft Exchange Server Elevation of Privilege Vulnerability
• CVE-2022-41082 – Microsoft Exchange Server Remote Code Execution Vulnerability

they impact Exchange Server 2013, 2016, and 2019, an authenticated attacker can trigger them to elevate privileges to run PowerShell in the context of the system and gain arbitrary or remote code execution on vulnerable servers.

Cybersecurity firm GreyNoise confirmed that threat actors are attempting to exploit the flaws since late September, Bleeping Computer reported.

Microsoft addressed both vulnerabilities with the release of Patch Tuesday updates for November 2022 security updates.

This week the popular researcher Will Dormann confirmed that PoC exploit code released by the security researcher Janggggg, which was exploited by threat actors in the wild, works against Exchange Server 2016 and 2019, and even against 2013 with some modifications. The expert demonstrated how to exploit the bug to execute calc.exe as SYSTEM.

Microsoft urges its customers to install the updates immediately to be protected against attacks exploring these flaws. The IT giant confirmed that they are aware of active exploits of related vulnerabilities that have been used in limited targeted attacks.

“Because we are aware of active exploits of related vulnerabilities (limited targeted attacks), our recommendation is to install these updates immediately to be protected against these attacks.” states Microsoft.

“Mitigations are not actual code fixes of specific vulnerabilities. Please install the November 2022 (or later) SU on your Exchange servers to address CVE-2022-41040 and CVE-2022-41082.”

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Pierluigi Paganini

(SecurityAffairs – hacking, ProxyNotShell)

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