Denial of service attacks – understanding and avoiding them

In October, a cyber attack on Internet provider Dyn made many web services and sites inaccessible, including several newscasters (Fox News, HBO, CNN, Weather Channel, etc.) and world-class sites Netflix, Paypal, Yelp, Starbucks, just to name a few.

This attack is considered the largest denial of service attack ever made. In order to better understand what happened, we will first of all recall some basic notions of Internet communications. We will continue by talking about botnets and their evolution, before we see the specifics of this recent attack. Finally, we will see how we can guard against such attacks.

Internet Communication Basics

Most Internet communications are of the client-server type. The Internet browser is often used as a “client” and sends requests to the server, asking it to display a Youtube video, for example.

Each server has its own IP address. When navigating on Google, for instance, the server that responds to our request may be different depending on our geographical location. This is made possible by using a Domain Name System (DNS).

These DNS servers will translate an address with the words “www.google.com” into an IP address. This notion is important for understanding the attack that targeted Dyn.

History of botnets

A “botnet” (combination of robot and network) is a network of computers infected by a virus, which turns them into passive entities that remain listening to future instructions. The person controlling the botnet can then send commands to his army of infected computers. For example, ask his robots to send spam or launch distributed denial of service attacks (DDoS). The distributed nature of this architecture makes detection of DDoS attacks difficult.

With the miniaturization and ever-decreasing cost of computing devices, more and more objects become “connected”. This creates an ever-growing network of printers, IP cameras and all kinds of objects that are connected to the web. All these devices are ultimately small computers, and like all computers, they are vulnerable to attacks.

Moreover, since few people take the time to configure these connected objects, most of them are configured with default passwords, making it even simpler for an attacker to compromise and infect them viruses.

We find ourselves in a situation where many objects connected to the Internet are infected by a virus. And these devices, like IP cameras, are constantly on, unlike our computers. During the most recent DDoS attack, this botnet managed to generate up to 1.2 Tb of data per second! This is a data rate equivalent to nearly 2,000 DVD-quality movies sent per second!

Why did this attack hurt so badly?

Denial of service attacks have traditionally targeted servers or websites of companies that are chosen either for activism (or hacktivism) reasons, or for the purpose of extorting money.

The reasons for this attack are not yet known, but what differs from previous ones is the target. For the first time, it was not site servers that were targeted, but the DNS servers of the Dyn company.

The sites of Twitter, Paypal and Netflix, for example, were fully functional. But by preventing us from knowing the address of the servers to connect, this attack made all these sites inaccessible.

How to defend against these attacks?

DDoS attacks often follow a well-established pattern. A first way to protect oneself therefore is to use systems that will detect the signatures of these attacks.

Another way to prevent is to implement redundancy on servers. By using load balancers, you can intelligently route traffic to multiple servers, improving the system’s resilience to high traffic flows.

But that’s not all! We also need to guard against infections, to prevent one of our systems from becoming a botnet member. To do this, you must first protect computers with antivirus software.

However, many connected devices are too simple to install an antivirus. It is therefore essential to analyze the inbound network traffic in your corporate network, both to detect known threats and zero-day vulnerabilities.

It is possible to further minimize the risk of infection of your systems by correlating and monitoring event logs, such as continuous network and systems monitoring, which is part of the services offered by ESI Technologies.

Finally, remember to keep systems updated, in order to mitigate the risk that known vulnerabilities can be exploited and use unique and complex passwords. Password management software exist to make your life easier.

A specialized information security firm such as ESI Technologies will be able to assist you in analyzing your needs and selecting the most effective and efficient solutions to mitigate the risks of botnet attacks on your systems.

Tommy Koorevaar, Security Advisor – ESI Technologies

Cryptolocker virus : how to clear the infection

Cryptolocker is a now well-known type of virus that can be particularly harmful to data stored on computer. The virus carries a code that encrypts files, making them inaccessible to users and demands a ransom (as bitcoin, for example) to decipher them, hence their name “ransomware”.
Cryptolocker type viruses infiltrate by different vectors (emails, file sharing websites, downloads, etc.) and are becoming more resistant to antivirus solutions and firewalls; it is safe to say that these viruses will continue to evolve and become increasingly good at circumventing corporate security measures. Cryptolocker is already in its 6th or 7th variation!

Is there an insurance policy?

All experts agree that a solid backup plan is always the best prescription for dealing with this type of virus. But what does a good backup plan imply, what would a well-executed plan look like?
The backup plan must be tested regularly and preferably include an offsite backup copy. Using the ESI cloud backup service is an easy solution to implement.
The automated copy acts as an insurance policy in case of intrusion. Regular backups provide a secondary offsite datastore, and acts as a fallback mechanism in case of malicious attack.

What to do in case of infection?

From the moment your systems are infected with a Cryptolocker, you are already dealing with several encrypted files. If you do not have in place a mechanism to detect or monitor file changes (eg a change of 100 files per minute), damage can be very extensive.

  1. Notify the Security Officer of your IT department.
  2. Above all, do not pay this ransom, because you might be targeted again.
  3. You will have no choice but to restore your files from a backup copy. This copy becomes invaluable in your recovery efforts, as it will provide you a complete record of your data.

After treatment, are you still vulnerable?

Despite good backup practices, you still remain at risk after restoring your data.
An assessment of your security policies and your backup plan by professionals such as ESI Technologies will provide recommendations to mitigate such risks in the future. Some security mechanisms exist to protect you from viruses that are still unknown to detection systems. Contact your ESI representative to discuss it!

Roger Courchesne  – Director, Security and Internetworking Practice – ESI Technologies

Is ransomware a myth?

Ransomware-Featured

A couple of weeks ago I was enjoying a business breakfast with a client when things turned bad for him. It seems it was a bad omen to talk about the challenges he was facing with regards to I.T. security since as we were talking, he received a text message from his staff informing him that they were hit with “CryptoLocker”. CryptoLocker encrypts a victim’s documents and demands a ransom for the decryption key usually paid in Bitcoins. In its Internet Security Threat Report 2014, Symantec “…noticed a significant upsurge in the number of ransomware attacks during 2013. During January Symantec stopped over 100,000 infection attempts. By December that number had risen more than six-fold.”
Not only it is it not a myth, it has become so widespread that according to the same report, “attackers have concluded that US$100 to $400 is the optimum ransom amount, and they will move to adjust their demand to avoid pricing themselves out of the market” and so my client was asked a 500$ ransom. Luckily for him he chose not to pay and opted for backups and cleanups as our friends from SourceFire has let us know that once you pay, you are being put on a list of people that are nice enough to pay the ransom, and therefore become subjected to further attacks.
Even though ransomware does not make up a huge percentage of overall threats, it is not a myth as my personal experience shows; and despite working for a company that has the expertise to help with the cleanup operations it is not in such circumstances that I enjoy being introduced the new clients.

Charles Tremblay, ESI Account manager