October 2019 Patch Tuesday

Microsoft has published its monthly Patch Tuesday updates, fixing 59 vulnerabilities, 8 of which were rated as “Critical”. This is a significant drop from last month. Adobe did not release any patches for this month, resulting in a very light patch Tuesday.

Internet Explorer and Edge

As usual, Internet Explorer and Edge contained multiple Critical vulnerabilities in their Visual Basic Scripting Engines. An attacker could exploit these vulnerabilities by luring a victim to a site hosting maliciously crafted content or uploading malicious content to a compromised site. The attacker would have privileges equal to that of the current user, so administrators running the browser are at risk of a full system takeover. This is yet another reminder to exercise the principle of least privilege.

Microsoft IIS

A user could elevate privileges by sending a malicious request to the IIS server. Microsoft has addressed this vulnerability by adding request sanitization to existing code. Attackers would need to have unprivileged credentials to access the affected component on the IIS server.

Remote Desktop Protocol

Clients that are forced to connect to a malicious server are vulnerable to an RCE vulnerability. Attackers exploiting this vulnerability would have privileges equal to that of the current user. An attacker can also cause an RDP server to stop responding by sending a maliciously crafted request to the server, resulting in a denial of service.

SharePoint

SharePoint Server also received some fixes this month. Attackers could exploit cross-site scripting, spoofing, and two elevation of privilege vulnerabilities by sending maliciously crafted requests to the web server. Each of these vulnerabilities was addressed by adding sanitization of incoming web requests.

Office

Microsoft Office received several fixes for various products. Attackers could leverage these vulnerabilities by convincing a user to open a maliciously crafted file. To best protect yourself from these kinds of vulnerabilities, ensure you know who is sending you a file before you attempt to open it.