Welcome back to this month’s Patch Tuesday. Microsoft has published its monthly updates, fixing 79 vulnerabilities, 17 of which were rated as “Critical”. This is a slight drop from last month. Three vulnerabilities were publicly disclosed prior to patching, and two were being actively exploited in the wild. The two vulnerabilities being exploited in the wild were elevation of privilege vulnerabilities in the Windows Common Log File System Driver, and in the Windows kernel.
Internet Explorer and Edge
As usual, Internet Explorer and Edge contained multiple Critical vulnerabilities in their Chakra 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.
The Windows Kernel had multiple vulnerabilities patched, one of which was actively being exploited in the wild. To exploit this, an attacker would have to run a specially crafted application to leverage ws2ifsl.sys, more commonly known as winsock. A successful exploit would result in system privileges granted to an unprivileged user.
Windows Common Log File System Driver
The Windows CLFS is a high-performance, general-purpose log file subsystem that dedicated client applications can use and multiple clients can share to optimize log access. However, like any application, it is prone to memory mismanagement, and since it runs as an elevated process, it can be leveraged to take complete control over the system. Researchers at Qihoo 360 Vulcan Team discovered the exploit in the wild.
Windows Secure Boot Security Features
The Windows Secure Boot process protects the Windows kernel during bootup from malicious devices. A vulnerability in this process was patched that allowed an attacker to gain access to protected kernel memory. In order to exploit this vulnerability, an attacker would need to have physical access to the machine prior to the next system reboot. The fix prevents access to certain debugging options when Windows Secure Boot is enabled.
Adobe Flash Player
A returning familiar face, Adobe Flash Player comes bearing more vulnerabilities to be patched. The two patched vulnerabilities could allow for a remote attacker to execute arbitrary code with the security context of the current user. Given that Adobe Flash Player is on the way out of service, you may wish to simply uninstall the product and its plugins from your system.