Tag Archive for: Windows

KB2992611 Breaks More than Web Servers

17 Nov 2014
November 17, 2014

This will be a short’ish post because I’m still trembling from the trauma…

I applied Windows Updates to a client’s production servers yesterday morning. Normally I wait an extra week to give things a chance to “shake out” and get tested in Dev (and other client’s servers) before I apply updates to production, but this time I saw KB2992611 in the announcements and wanted it installed ASAP.

This security update resolves a privately reported vulnerability in the Microsoft Secure Channel (Schannel) security package in Windows. The vulnerability could allow remote code execution if an attacker sends specially crafted packets to a Windows server.

Things were fine yesterday (low load) but once the load started ramping up today the web server was pretty much at 100% CPU – most of it in LSASS.EXE. Everything was very slow and painful. Lots of research, hours of trial and error – including rolling back yesterday’s updates – to no avail. Very frustrating.

As spirits were plummeting, Hans, the client’s resident genius, found this “Microsoft does it again” article. We then realized we should be removing this patch from ALL tiers of the application, not just the front-end. Removed it from the database server and middle app server and then the web server’s load dropped back to normal range. Time for a beer.

Moral of the story? Don’t always focus on the server with high CPU. Look at all the dependencies, especially when you know/suspect you have a bad update in the mix.

Relocate Dropbox to a Removable Drive

05 Oct 2014
October 5, 2014

Most of my recent rigs have had 120 GB SSD drives as primary drives and then something larger and slower/magnetic for data. However, the tablet I recently bought only has the 1 SSD drive.

While that isn’t really a problem, the fact that my Dropbox library keeps getting larger and larger is making it a problem. “No problem,” thought I. “I’ll just toss in a 32 GB microSD drive. That’ll fix it.”

Well, Dropbox doesn’t let you relocate it to removable drives:

No Removable Media dialog

If only there was a way to use removable storage in a way that “looked” permanent… Oh, but there is. The windows utility mklink is the answer here.

I created a “C:\SD” directory on the SSD. My microSD card was at G:\. I then typed the following command:

mklink /d /J C:\SD G:\

Problem solved. Back to Dropbox and tell it I want to relocate my files to C:\SD\Dropbox and it was quite happy.

Freeing up Space on Server 2008 R2 (and 2012)

15 Jul 2014
July 15, 2014

We manage a pile of Windows Server 2008 R2 machines across a bunch of clients and many of those servers weren’t necessarily built by us. As such, sometimes space is allocated… poorly… And many of those servers are frequently dancing on the edge of running out of space on the C: drive.  (I will spare you the rant about 20 GB C: partitions. Maybe.)

While there’s always the option of resizing partitions, there isn’t always the time to do it. Either arranging a convenient time to take the server down during business hours or the more common after-hours (nights and weekends) time to travel onsite and do it at a time that doesn’t inconvenience anyone. Either way, never convenient for everyone.

What usually happens is I run WinDirStat on the server and look for anything obvious that can be cleared. Recycle bin? Logs? Assorted temp directories? That sort of stuff.

What often shows up? C:\windows\WinSxS directory. You know you can’t just delete it, right? Bad form.

 Good news. I recently stumbled over a blog post that I have found incredibly helpful for cleaning up WinSxS. Turns out that if your server is reasonably current in patches (you need KB2852386), the Disk Cleanup Wizard has the ability to cleanup Windows Update files.

Can’t find the Disk Cleanup Wizard? Well yeah, there’s a wrinkle there: first you need to install the Desktop Experience Feature. And reboot.

Yeah, I know, I know, but it is worth the amount of space you’ll reclaim. Honest.

And good news, this applies to Server 2012 and R2 as well. On a couple older servers I have reclaimed a lot of space doing this. Which is a heck of a lot easier than rooting around a bunch of random directories trying to find things to delete or compress. Right?

A Quick Look at IIS Crypto

22 Apr 2014
April 22, 2014

For many years now – I think about a decade — I have been building and managing Windows Web servers for a SaaS company. First as a contractor, then an employee and most recently as a consultant (tip: relationships matter). While I don’t have it down to an automated science, I do have pretty detailed checklists that I run through as part of each build.

My goal has always been to keep the server configurations consistent yet adapt as each new Windows Server release comes out. My first checklist was for a Server 2000 build. The one I updated last week was for 2012 R2. That’s covering some serious territory.IIS has certainly changed a lot over the years.

Of course, a big part of the builds revolves around security. One aspect of security is managing the SSL protocols and cipher suites offered by IIS. And, more importantly, which ones you do not wish to offer. I’ve documented this over the years and done some automation with batch files, vbs files (I know, I know…) and even .reg (registry import) files.

As I was updating the most recent servers last week I thought I had better do some quick research and make sure my notes were still current. These things date back 5 – 10 years after all. For instance, I know just half a year ago we went through the servers and disabled RC4 at Microsoft’s suggestion. That was never folded into my build notes…

While looking for SSL security updates I stumbled over a very handy little utility: IIS Crypto. I downloaded the tool, tried it on a dev server and then hit it with an external Qualys scan. It worked great – and fixed up a few holes that I had incorrectly plugged over the years (whoops). Now IIS Crypto is part of my toolbox.

IIS Crypto Screenshot

Just download and run it on your web server and choose the “Template” that applies. For me, that’s Best Practices with one click, then a second click to disable RC4 128/128 just to be consistent. Hit apply, schedule a reboot and you’re in good shape. Need to be PCI or FIPS compliant? Those are templates there as well.

There’s even a quick way to scan yourself from Qualys SSL labs.

Very slick. Highly recommended.

From their site:

IIS Crypto is a free tool that gives administrators the ability to enable or disable protocols, ciphers, hashes and key exchange algorithms on Windows Server 2003, 2008 and 2012. It also lets you reorder SSL/TLS cipher suites offered by IIS, implement best practices with a single click and test your website.