Welcome to Patch Tuesday, June 2019. Microsoft has published its monthly updates, fixing 88 vulnerabilities, 21 of which were rated as Critical. Additionally, the updates include fixes for four of the five zero-day vulnerabilities that “SandboxEscaper” had been selling online over the course of the last month. None of them are known to have been exploited in the wild.

Internet Explorer and Edge

This month saw some heavy action on Internet Explorer and Edge, with the Chakra Scripting engine receiving nine remote code execution vulnerability fixes. To exploit these vulnerabilities, an attacker would lure a victim to a malicious website, and then the scripting engine would execute the attacker’s code. Microsoft has rated these vulnerabilities as likely to be exploited on the latest software release. As usual, the attacks would have the security context of the current user, which means that exercising the principle of least privilege mitigates these vulnerabilities.

Adobe Flash Player

Adobe has released fixes for Adobe Flash Player, as usual. An attacker exploiting the use-after-free vulnerability would be able to execute code within the context of the current user. Attackers would likely leverage this vulnerability by luring a victim to a malicious website or uploading malicious content to a compromised site.

Office

Office products received the usual round of fixes. There were multiple vulnerabilities that can result in remote code execution across multiple products, all with the security context of the current user. Once again, this is a reminder to enforce least privilege across all your applications.

Kerberos

Kerberos was patched for a vulnerability in its local security authority subsystem service. Attackers would be able to cause a denial of service in this key exchange system, potentially bogging down users. A vulnerable system would then reboot, preventing user authentication. The local security authority subsystem service has been updated to drop such requests.

Hyper-V

Microsoft’s virtualization software was vulnerable to a remote code execution vulnerability. A user on a guest operating system could send input to the host that would cause the host to execute arbitrary code. This has particularly damaging ramifications in cloud virtualization environments that utilize Hyper-V, since the host controller can potentially access other guest operating systems.

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