Chuck Leaver – Be Careful Of This Microsoft Word Feature And Phishing Attacks

Written By Josh Harriman And Presented By Chuck Leaver

 

An intriguing multifaceted attack has been reported in a current blog by Cisco’s Talos
Intelligence group. I wanted to speak about the infection vector of this attack as it’s quite
fascinating and something that Microsoft has actually pledged not to repair, as it is a feature
and not a bug. Reports are can be found about attacks in the wild which are making use of a
feature in Microsoft Word, called Dynamic Data Exchange (DDE). Details to how this is
accomplished are reported in this blog from SecureData.

Special Phishing Attack with Microsoft Word

Attackers constantly search for brand-new methods to breach a company. Phishing attacks are one
of the most typical as assailants are relying on that someone will either open a document sent
out to them or go to a ‘faked’ URL. From there an exploit on a susceptible piece of software
usually provides access to begin their attack.

However in this case, the documents didn’t have a malicious item embedded in the Word doc,
which is a preferred attack vector, but rather a sly way of utilizing this function that
permits the Word program to connect out to obtain the real malicious files. By doing this they
could hope or rely on a better success rate of infection as harmful Word files themselves can
be scanned and erased prior to reaching the recipient.

Hunting for Suspicious Behaviors with Ziften Zenith

Here at Ziften, we wanted to have the ability to alert on this behavior for our clients.
Finding conditions that show ‘odd’ habits such as Microsoft Word spawning a shell is
fascinating and not expected. Taking it further on and trying to find PowerShell running from
that spawned shell and it gets ‘extremely’ intriguing. Through our Search API, we can discover
these behaviors anytime they happened. We do not need the system to be switched on at the time
of the search, if they have actually run a program (in this case Word) that exhibited these
behaviors, we can discover that system. Ziften is constantly gathering and sending appropriate
procedure info which is why we can discover the data without depending on the system state at
the time of searching.

In our Zenith console, I looked for this condition by looking for the following:

Process → Filepath includes word.exe, Child Process Filepath includes cmd.exe, Child Process
commandline includes powershell

This returns the PIDs (Process ID) of the processes we saw startup with these conditions. After
this we can drill down to see the critical information.

In this very first image, we can see details around the procedure tree (Word spawning CMD with
Powershell under that) on the left, and to the right side you can see details like the System
name and User, plus start time.

Below in the next image, we take a look at the CMD procedure and get details regarding what was
passed to Powershell.

Most likely when the user had to answer this Microsoft Word pop up dialog box, that is when the
CMD shell used Powershell to head out and obtain some code that was hosted on the Louisiana Gov
website. In the Powershell image below we can see more details such as Network Connect info
when it was reaching out to the website to pull the fonts.txt file.

That IP address (206.218.181.46) is in fact the Louisiana Gov website. Often we see fascinating
data within our Network Connect information that might not match exactly what you expect.

After developing our Saved Search, we can inform on these conditions as they occur throughout
the environment. We can likewise develop extensions that alter a GPO policy to not allow DDE or
even take additional action and go and discover these files and remove them from the system if
so wanted. Having the ability to find fascinating mixes of conditions within an environment is
extremely effective and we are delighted to have this function in our offering.

~leaverchuck1


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