Saturday, January 06, 2018

WindowsIR 2018: First Steps

Ransomware
I haven't mentioned ransomware in a while, but I ran across something that really stood out to me, in part because we had a couple of things we don't usually see in the cybersecurity arena through the media...numbers. 

Okay, first, there's this article from GovTech that describes an issue with ransomware encountered by Erie County Medical Center in April, 2017.  Apparently, in the wee hours of the morning, ransom notes started appearing on computer screens, demanding the equivalent (at the time) of $30,000USD to decrypt the files.  The hospital opted to not pay the ransom, and it reportedly took 6 weeks to recover, with a loss of $10MUSD...yes, the article said, "MILLION". 

A couple of other things from the article...the hospital reportedly took preparatory steps and "upgraded" their cybersecurity (not sure what that means, really...), and increased their insurance from $2MUSD to $10MUSD. Also, the hospital claimed that it's security was now rather "advanced", to the point where the CEO of the hospital stated, “Our cybersecurity team said they would have rated us above-average before the attack.”

So, here we have our numbers, and the fact that the hospital took a look at their risks and tried to cover what they could.  I thought I'd take a bit of a look around and see what else I could find about this situation, and I ran across this Barkly article, that includes a timeline of the incident itself.  The first two bullets of that timeline are:

Roughly a week before the ransom notes appear attackers gain access to one of ECMC's servers after scanning the Internet for potential victims with port 3389 open and Remote Desktop Protocol (RDP) exposed. They then brute-force the RDP connection thanks to "a relatively easy default password."

Once inside, attackers explore the network, and potentially use Windows command-line utility PsExec to manually deploy SamSam ransomware on an undisclosed number of machines...

Ah, yes...readers of this blog know a thing or two about Samsam, or Samas, don't you?  There's this blog post that I authored, and there's this one by The Great Kevin Strickland.

Anyway, I continued looking to see if I could find any other article that included some sort of definitive information that would collaborate the Barkly article, and while I did find several articles that referred to the firm that responded to and assisted ECMC in getting back up and running, I had trouble finding anything else that specifically supported the Barkly document.  This article states that the ransom note included 'hot pink text'...some of the variants of Samas ransomware that I looked at earlier this year included the ransom note HTML in the executable itself, and used a misspelled font color...the HTML tag read "DrakRed".  I did, however, find this BuffaloNews.com article that seemed to collaborate the Barkly article.

So, a couple of lessons we can learn from this...

1.  A vulnerable web or RDP server just hanging out there on the Internet, waiting to be plucked is not "above-average" cybersecurity.

2.  An EDR solution would have paid huge dividends; the solution gets programmed into the budget cycle, and can lead to much earlier detection (or prevention) of the sort of thing.  Not only can an EDR solution detect the adversary's activities before they get to the point of deploying the ransomware, but it can also prevent processes from running, such as if the WinWord.exe process (MS Word) attempts to launch something else, such as a command prompt, run Powershell, run rundll32.exe, etc. 

If you still don't think ransomware is an issue, consider what happened to Spring Hill, TN, and Mecklenberg County, NC.  The CEO of the Fortalice Solutions (the cybersecurity firm that responded to assist Mecklenberg Cty), Theresa Payton, discussed budget issues regarding IR in this CSOOnline article; incorporating early detection into the IR plan, and by extension, the budget, will end up saving organizations from the direct and indirect costs associated with incidents.

EDR Solutions
Something to keep in mind is that your EDR solution is only as good as those who maintain it.  For example, EDR can be powerful and provide a great deal of capabilities, but it has to be monitored and maintained.  Most, if not all, EDR solutions provide the capability to add new detections, so you want to make sure that those detections are being kept up to date.  For example, detecting "weaponized" or "malicious" Word documents...those email attachments that, when opened, will launch something else...should be part of the package.  Then when something new comes along, such as the MS Word "subdoc" functionality (functionality is a 'feature' that can be abused...), you would want your EDR solution updated with the ability to detect that, as well as your infrastructure searched to determine if there are any indications of someone having already abused this feature.

RegRipper Plugin Update
The morning of 1 Jan 2018, I read a recent blog post by Adam/Hexacorn regarding an alternative means that executable images files can use to load DLLs, and given my experience with targeted threat hunting and the pervasiveness I've seen of things like DLL side loading, and adversaries taking advantage of the DLL search order for loading malicious DLLs (loaded by innocuous and often well-known EXEs), I figured it was a good bit of kit to have available...so I wrote a RegRipper plugin.  It took all of 10 min to write and test, mostly because I used an already-existing plugin (something Corey Harrell had mentioned a while back in his blog) as the basis for the new one.  I then uploaded the completed plugin to the GitHub repository.

4 comments:

Unknown said...

Thanks for sharing!

Mitch Impey said...

Happy New Year
Harlan ! Thanks for the updates and expecially the reg ripper plug in !

Mari DeGrazia said...

Great point about the numbers. We have been seeing quite a few crypto currency cases, and I have to wonder if the attackers are making more than what it ends up costing the client in legal and forensics fees - not to mention the hours spent by employees dealing with it.

Anonymous said...

Thank you for this, Harlen. I always enjoy reading your research and experiences. Your willingness to share with the cybersec and dfir communities is appreciated. I also enjoy seeing you publicly correct the wayward when you include substantial information with your responses. Cheers, Jason.