Hello everyone! This episode will be about relatively recent critical vulnerabilities. Let’s start with Microsoft Patch Tuesday for October 2021. Specifically, with the vulnerability that I expected there, but it didn’t get there.

Autodiscover leak discovered by Guardicore Labs

“Autodiscover, a protocol used by Microsoft Exchange for automatic configuration of clients such as Microsoft Outlook, has a design flaw that causes the protocol to “leak” web requests to Autodiscover domains outside of the user’s domain but in the same TLD (i.e. Autodiscover.com).” Guardicore Labs acquired multiple Autodiscover domains and have captured 372,072 Windows domain credentials in total. It seems Microsoft have chosen to ignore this issue. No CVE, no Outlook or ActiveSync patches. The only fix is to ban the “Autodiscover.” domains on devices.

Microsoft Patch Tuesday for October 2021

74 vulnerabilities: 1 Critical, 30 High, 43 Medium.

Elevation of Privilege – Windows Kernel (CVE-2021-40449)

It is a use-after-free vulnerability in the NtGdiResetDC function of the Win32k driver. A detailed technical description is available in Kasperky Securelist post, but, in short, the vulnerability can lead to leakage of kernel module addresses in the computer’s memory. This vulnerability is being exploited in the wild by APT MysterySnail. All servers and desktops should be updated.