Nyatya Wiper Malware

Nyatya – a Wiper Malware disguised as Ransomware

Nyatya Wiper Malware

A new malware Nyetya (combination of words from Nye Petya, meaning NOT Petya), also known as Petrwrap and GoldenEye has been spreading globally over the last 24 hours.

This virus is distinct from WannaCry and other initially suspected variants, it has some unique new features which makes it harder to detect and defend against, clearly showing that today’s malware landscape is an evolving space. This rapidly changing threat landscape has a number of factors including; leaked tools from government agencies, more advanced security controls that require advanced malware (the cat and mouse game) or just because attackers are more determined and more capable.

Other popular researchers (links below) say Nyetya is more of a nation (state) attack towards a specific country (Ukraine) that is disguised as ransomware so its true nature would remain hidden in the shadow of recent WannaCry ransomware.

Some Characteristics of Nyetya and why it is different

  1. There is recent research that showed Nyetya, despite having major resemblance to Petya ransomware, in fact does not keep a copy of the encrypted MTL (Master File Table) and MBR (Master Boot Record) that it replaces with the random note. That means that even in the case that the user gets its decryption keys there is nothing to decrypt. This behavior resembles specific type of malware called Wiper Malware. All machines that are infected cannot be recovered. Also, the email for contract with the attackers is now disabled so there is no possibility for getting the decryption keys. Obviously, the attackers have not intended to milk the ransom and get rich for their efforts.
  2. It encrypts the master boot record, which makes the whole system unusable and causes more damage. Previous crypto viruses (ransomware) were encrypting specific file extensions
  3. It does not use a common attack vector from the Internet

It does not infect by scanning ports for vulnerable services, nor uses phishing (mails with crafted content with specific covert malware links), nor file attachments or web sites that host malicious content. Instead the initial way in was via an update in a polular accounting software in Ukraine (called MeDoc). The software was tricked into auto-updating with a malicious file (Perfc.dat). Once it is inside it uses the Eternal Blue (SMBv1) exploit to spread (same as WannaCry) but also two other administrative tools (PSexec and WMI) which in general are valid and legitimate tools used inside a network. The use of these tools would not raise any alarms on network security controls. The malware is capable of stealing the current user’s token and use it to distribute itself to other devices via PSexec (still unclear how it is able to steal the token) or again to steal the current user credentials and use them via WMI.

  1. No external Internet scans

There is no evidence of external scans (from the internet) in order to locate unpatched SMB services. The only scans that the virus conducts are horizontal, once it is inside the protected network. That makes the virus very hard to detect as most organisations do not have visibility within their network for such activity

  1. No Command and Control functionality

The virus does not use C&C so any reputation based security controls cannot detect it. IP addresses/domains reputation is widely used to detect zero-day attacks and to monitor the spread of the virus. That does not seem feasible protection from Nyetya

  1. Special attention has been paid to cleaning up any remaining data and logs

All of these unique characteristics point to the fact that cyber criminals have changed their tactics (after the failure of WannaCry due to the incidental but timely discovery of the killswitch) and want the malware spread to be as stealthy as possible.

Protecting yourself from the attack

A short summary of techniques necessary to protect against the attacks are listed below. These cannot be undertaken in isolation and it is assumed that good security practices are already in place such as disaster recovery strategy as well security control such anti-malware controls.

  1. Patch your systems (MS17-010 should be applied), close off any SMBv1 services (disable)
  2. Do not use admin/elevated privileged accounts for normal users
  3. Monitor your network and endpoints for PSexec and WMI communication and try to establish if that is valid communication (could be based on which one the administrators use and also the time of the day)
  4. Monitor your internal network segments using an IDS/IPS

Which type of network security controls are best suited to discover and prevent malware spread?

While other forms of malware attack may have been stopped by reputation based or email and web security controls, neither would have been effective in this instance. An essential tool in the armoury of security controls is endpoint security such as Cisco AMP for Endpoints, which actively analyse the behaviour of executable files on the system and perform sandboxing.

IDS/IPS network controls are able to catch lateral scans and spread via SMBv1 exploit only if they can see the traffic (actively monitoring traffic on the same logical domain).  The most common IDS/IPS deployment model is on the Internet edge, as this malware does not use external scans or gets distributed via normal Internet related channels (mail and web) these controls are not effective.

Following general security best practises is also beneficial – having backup of important systems/files, having proper application visible monitoring on the network and trying to detect unusual behavior, that of course requires both the tools and the people (analyst).

Used materials:

http://blog.talosintelligence.com/2017/06/worldwide-ransomware-variant.html

http://thehackernews.com/2017/06/petya-ransomware-wiper-malware.html

https://www.wired.com/story/petya-ransomware-ukraine/

Cisco Umbrella image

Cisco Umbrella – light, easy to deploy and powerful

Cisco Umbrella image

Cisco currently has multiple endpoint security solutions in place – CWS (Cloud Web Security / Scansafe), Umbrella (OpenDNS) and AMP for endpoints are prime examples. AMP is a different breed of endpoint protection, it relies heavily on detection based on heuristics and cloud sandboxing, where as CWS and OpenDNS both concentrate very strongly on making sure your Internet browsing is secure and save.

A bit of history behind the story: when Cisco acquired Scansafe and then sometime later OpenDNS, a lot of people were wondering why Cisco needs two products that have such a large overlap in functionality. At first CWS looked like it was going to last, it had a large customer base, was heavily pushed by Cisco Sales and managed to get a big boost from existing Cisco customers that needed protections for this security gap which was opened by remote/roaming employees.

OpenDNS with most of its customers using the free version seemed like an outsider. It could only detect things based on DNS and was not tunneling any traffic back to the cloud, so it seems like it is not going to be a valid corporate level endpoint protections tool. People underestimated the power of DNS. OpenDNS has something very valuable, via its free version, it had the ability to see a large percentage of worldwide DNS request and using its strong security team it provided a more universal and complete protections that focuses on more than just web browsing. Almost all internet communication is based on DNS, the use of static IPs has been greatly reduced for couple of reasons – for non-malicious users the DNS provides first ease of use and flexibility that static IPs could not, for malicious users – the use of static IPs proved to be unwise as IPs were very quickly blocked (blacklisted) by ISPs and security tools. The result of massive DNS use was that your DNS provider could actively see where your traffic is going and block it (monitoring and enforcement) for all applications (not only Web based).

It was clear Cisco would have to make a choice and I believe they have made the correct one – Cisco is moving forward with the Umbrella and retiring the CWS.

What is Umbrella?

In short, the paid version of OpenDNS, which can support and integrate with other Cisco Products.

How does it work?

It works by forwarding DNS request to OpenDNS servers, either by registering your public IP with Umbrella and forwarding your internal DNS to OpenDNS servers, or by setting your network equipment (DHCP) to directly give out OpenDNS servers for DNS usage, in case the company does not have own internal DNS servers. That secures devices within the offices of the company. For Roaming devices, Umbrella has a Roaming Client (a small agent installed on endpoints, supports Windows and MACs, with vision to support Linux in the future) that makes sure all DNS requests are forwarded to the OpenDNS cloud.

It is very important to note that Umbrella does not work like a traditional Web Proxy, it does not send the all user traffic to the cloud for inspection, it only works and makes decisions based on the information from the DNS requests from the client. User traffic is send for inspection to the cloud only for gray/risky domains (traffic to malicious ones is blocked straight away). Furthermore, this redirection of traffic works for both Agent and Agentless deployments by using the DNS reply to forward the traffic to the Umbrella Cloud proxy service called Umbrella Intelligent Proxy.

The result is a better user experience (instantaneous decision to allow and block traffic to majority of traffic based on good and bad domains), lower deployment complexity and lower operational costs.

How is it configured?

Umbrella is one of the easiest deployments we have seen. It has excellent documentation and simple steps to help you redirect your office traffic to the cloud and deploy Roaming clients to your endpoints. All the management is done via portal in the web (https://dashboard.umbrella.com/). It has a very simple and effective portal layout with intuitive access to both management entities (managed identities and policies) but also monitoring and reporting. A typical simple implementation of Umbrella can be done in a matter of hours, without the need of any on-premise hardware installations (except when AD integration is needed, a lightweight virtual server needs to be installed)

Does it support AD integration for enhanced user visibility?

Yes, it does, it needs a VA (Virtual Appliance, a lightweight virtual server running on either ESX or Hyper-V). The VA servers allows Umbrella to see internal information such as private IP addresses of users and further performs an AD integration with MS AD (servers as a connector) so Umbrella Dashboard can see AD names and be able to define policies based on groups and create reports that include clients AD username (very handy if you want to know who exactly is making all of these malicious outbound requests (such as Command and Control traffic et).

Can it block based on connections that do not use DNS?

Yes, it can, there is a functionality called IP Layer Enforcement that builds IPSEC tunnels to the Umbrella cloud and forward requests to it in case the connection has a suspicious (flagged as malicious) IP address. This is possible only if the client is using Roaming Agent (either the Umbrella one or Anyconnect one).

Does it have integration with other Cisco products?

Umbrella has a module for Anyconnect (Cisco Umbrella Roaming Security module is available for Anyconnect version 4.3 MR1 and newer), which means if the customer has Anyconnect already deployed, there is no need to install Umbrella Roaming Agent. Also, OpenDNS security team is now part of Cisco Talos so OpenDNS both feeds Talos with DNS information but also benefits from Talos to device either certain domain or IP address are deemed risky.

Does it support SSL decryption?

Yes, Umbrella supports SSL decryption so it can do deep inspection for traffic destined for risky/suspicious domains. The configuration of the SSL decryption is very straight-forward, administrators are prompted to download Umbrella (OpenDNS) certificated from the Dashboard and then these certificates need to be installed as trusted on endpoint machines. Next step is just to enable the SSL decryption.

Conclusion:

Umbrella provides enterprise level endpoint security with lower latency than traditional proxies, low capex and deployment costs.

References:

http://www.cisco.com/c/en/us/products/collateral/security/cloud-web-security/eos-eol-notice-c51-738244.html

https://support.umbrella.com/hc/en-us/articles/231246528-Umbrella-Intelligent-Proxy-FAQs

https://umbrella.cisco.com/products/features/intelligent-proxy

https://deployment-umbrella.readme.io/docs/1-introduction

https://deployment-umbrella.readme.io/docs/1-ad-integration-setup-overview

https://deployment-umbrella.readme.io/docs/anyconnect-umbrella-roaming-security-client-administrator-guide