Microsoft has released fixes for about 70 vulnerabilities for its June 2023 Patch Tuesday release, and while none are listed as being actively exploited of publicly known, there are still a handful of critical-rated vulnerabilities that IT admins should prioritize this month.
That list of bugs that should be prioritized includes two remote code execution vulnerabilities in Microsoft Exchange Server, an elevation of privilege bug in Microsoft SharePoint, a trio of remote code execution flaws in Windows Pragmatic General Multicast, and a handful of others.
Based on input from security researchers from Zero Day Initiative (ZD), Tenable, Immersive Labs and others, here is a look at the vulnerabilities that warrant more attention for the June 2023 Patch Tuesday release.
CVE-2023-32031 – Microsoft Exchange Server Remote Code Execution Vulnerability
If this looks familiar, you aren’t alone. Microsoft has issued fixes for a number of Exchange Server remote code execution bugs in recent years, and this one is a bypass of fixes for CVE-2022-41082 and CVE-2023-21529, with the latter listed as being under active exploitation.
This vulnerability exists within the Command class, and the issue results from the lack of proper validation of user-supplied data, which can result in the deserialization of untrusted data. This bug requires the attacker to have an account on the Exchange server, but successful exploitation could lead to executing code with SYSTEM privileges.
CVE-2023-28310 – Microsoft Exchange Server Remote Code Execution Vulnerability
This is the other Exchange RCE bug listed this month, and like its twin this month, is rated as important but considered more likely to be exploited. This also requires an attacker to be authenticated, so an attacker will need valid credentials.
According to researchers, both Exchange Server bugs closely mirror the vulnerabilities identified as part of the ProxyNotShell exploits. Successful exploitation could result in an attacker gaining access to an organization’s email account, or even the ability to impersonate any user.
Since attackers are adept at stealing valid credentials via phishing attacks, these should not be ignored.
CVE-2023-29357 – Microsoft SharePoint Server Elevation of Privilege Vulnerability
According to researchers, this critical-rated vulnerability is used to bypass authentication due to a flaw within the ValidateTokenIssuer method. Microsoft lists enabling the AMSI feature to mitigate this flaw, but organizations are still urged to deploy the update as soon as possible.
Exploitation is achieved by sending a spoofed JWT authentication token to a vulnerable server, giving them privileged of an authenticated user on the target, researchers say.
CVE-2023-29363/32014/32015 – Windows Pragmatic General Multicast (PGM) Remote Code Execution Vulnerability
This trio of vulnerabilities, all critical-rated, allow a remote, unauthenticated attacker to execute code on an affected system where the messag queuing service s running in a Pragmatic General Multicast (PGM) Server environment. This is the third month in a row that Microsoft has patched a critical-rated bug in this component.
For successful exploitation, a system must have message querying services enabled.
For further June 2023 Patch Tuesday analysis, consult research blogs from Zero Day Initiative, Tenable, Immersive Labs and others.
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