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Microsoft Patch Tuesday - January 2012

The first round of security bulletins from Microsoft this year raises some interesting questions about the vulnerabilities being patched. I found the following three advisories particularly interesting:

From MS12-002:

The vulnerability could allow remote code execution if a user opens a legitimate file with an embedded packaged object that is located in the same network directory as a specially crafted executable file. An attacker who successfully exploited this vulnerability could gain the same user rights as the logged-on user.

MS12-002 is ranked by Microsoft as important. Sure, it does require that the user browse file systems, however users can be baited, or even forced, to browse to a network share. Social engineering attacks can lure victims to specific sites, and SMB share paths can be embedded inside web pages and URLS, forcing the user to browse to a share or even a specific file.

From MS12-004:

(Windows Media Player): Vulnerabilities in Windows Media Player Could Cause Remote Code Execution. This bulletin – the only one in January’s set to include multiple CVEs – addresses two issues that could arise if a would-be attacker sent a malicious MIDI or DirectShow file to a targeted user.

As I learn how organizations manage large deployments of Windows desktops, I am amazed at how the technology has grown and evolved over the years. Administrators now can have complete control of which software is installed on the end user workstations, and maybe something like Windows Media Player is not required on all desktops, especially ones that have access to specific kind of information.

From MS12-006:

This is an information disclosure vulnerability that allows the decryption of encrypted SSL/TLS traffic. This vulnerability primarily impacts HTTPS traffic, since the browser is the primary attack vector, and all web traffic served via HTTPS or mixed content HTTP/HTTPS is affected.

MS12-006 is ranked by Microsoft as "Important" and denoted as "information disclosure". I believe that is a poor way to represent a vulnerability that "could allow" an attack to decrypt your SSL traffic. Sure, its not remote exploitability, however, if the goal of an attacker is to gain access to your sensitive information, decrypting your SSL traffic is a great way to achieve that goal. This does require that an attacker gain a foothold somewhere in your organization, but as so many breaches have shown, this is not often a terribly difficult task to achieve.

The bottom line is that you need to choose which software is installed on your systems, and likely try to pair it down as much as possible. Also, when you are trying to defend your network, and prioritize patches, do so with the notion that an attacker could likely be on a machine on the inside of your network. I've found some of the most resilient networks have built security around the "there is already an attacker on the inside" concept.

To help evaluate the vulnerabilities addressed by Microsoft’s Patch Tuesday, Tenable's Research team has published Nessus plugins for each of the security bulletins issued this month: