Worms wiggling inside your networks are a lot harder to stop

Posted by   Martijn Grooten on   Aug 3, 2017

Damaging though they were, the recent WannaCry and (Not)Petya outbreaks taught security practitioners many valuable lessons. Unfortunately, they taught important lessons to malware authors too.

What contributed to the damage in both cases was the malware's ability to spread internally using a number of methods, most prominently (though in (Not)Petya's case not exclusively), a vulnerability in the SMB protocol that many organizations had failed to patch.

The authors of the 'TrickBot' banking trojan took note of this, and a new version of the malware, discovered by Deloitte researcher Luciano Martins and analysed by Flashpoint's Vital Kremez, suggests that they are experimenting with a module that uses SMB for lateral movement, though the module hasn't been fully implemented yet.

trickbotsmb.png

Trickbot's SMB implementation, as found by Luciano Martins.


Computer worms were a plague around the turn of the century, but thanks to improved security, the ubiquity of firewalls and the often overlooked benefits of NAT, malware that replicates fully automatically tends to be quite rare these days. But while the problem of malware spreading to other networks may have been mitigated pretty well, there are still many opportunities when it comes to malware spreading laterally within an organization.

For every method of lateral movement used by malware, there is probably a fairly easy way to prevent it; in the case of SMB that would be turning it off unless absolutely necessary, and in such cases always patching. But as malware authors shift their focus, it is likely that they will find many other ways to exploit the interconnectedness of computers within an organization. This won't be an easy problem to solve.

Of course, removing connections when they aren't needed could go a long way towards mitigating the damage, and there is a lot of value in network segmentation. But this approach isn't entirely painless. At VB, we have (touch wood!) never suffered from an attack that moved laterally within our networks. We have, however, spent quite a few frustrating hours having to find solutions to connections having become unavailable due to increased segmentation.

For more on recent changes to Trickbot, I recommend hasherezade's analysis at Malwarebytes's blog.

On the lessons learned from WannaCry that can be used for the common good, Razvan Gavrila from the EU's network agency ENISA will give a Small Talk at VB2017 in Madrid. Speaking of which, analyses of recent changes in malware would be excellent topics for last-minute papers – the call for last-minute papers closes on 3 September!

twitter.png
fb.png
linkedin.png
googleplus.png
reddit.png

 

Latest posts:

VB2017 paper: Walking in your enemy's shadow: when fourth-party collection becomes attribution hell

We publish the VB2017 paper and video by Kaspersky Lab researchers Juan Andres Guerrero-Saade and Costin Raiu, in which they look at fourth-party collection (spies spying on other spies' campaigns) and its implications for attribution.

Didn't come to VB2017? Tell us why!

Virus Bulletin is a company - and a conference - with a mission: to further the research in and facilitate the fight against digital threats. To help us in this mission, we want to hear from those who didn't come to Madrid. What is your impression of…

Montreal will host VB2018

Last week, we announced the full details of VB2018, which will take place 3-5 October 2018 at the Fairmont The Queen Elizabeth hotel in Montreal, Quebec, Canada.

VB2017 preview: Beyond lexical and PDNS (guest blog)

In a special guest blog post, VB2017 Silver sponsor Cisco Umbrella writes about a paper that researchers Dhia Mahjoub and David Rodriguez will present at the conference this Friday.

Avast to present technical details of CCleaner hack at VB2017

The recently discovered malicious CCleaner version has become one of the biggest security stories of 2017. Two researchers from Avast, the company that had recently acquired CCleaner developer Piriform, will share the results of their investigations…