Apr 18, 2016
How Ransomware Is Spread
As you’ve almost certainly seen in the news lately, ransomware has emerged as a major threat to individuals and businesses alike. It has become a lucrative option for cyber extortionists. When the malware is run, it locks victim’s files and allows criminals to demand payment to release them.
Organizations of all types and sizes have been impacted, but small businesses are particularly vulnerable to attacks. Ransomware is on the rise. A recent study conducted by security software vendor McAfee Labs identified more than 4 million samples of ransomware in Q2 of 2015, including 1.2 million new samples. That compares with fewer than 1.5 million total samples in Q3 of 2013 (400,000 new). This type of malware is distributed in a variety of ways and is difficult to protect against because, just like the flu virus, it is constantly evolving.
There are a few dominant types, or families, of ransomware in existence. Each type has its own variants. It is expected that new families will continue to surface as time goes on. Historically, Microsoft Office, Adobe PDF and image files have been targeted, but McAfee predicts that additional types of files will become targets as ransomware continues to evolve. Most ransomware uses the AES algorithm to encrypt files, though some use alternative algorithms. To decrypt files, cyber extortionists typically request payment in the form of Bitcoins or online payment voucher services, such as Ukash or Paysafecard. The standard rate is about $500, though we’ve seen much higher. Cyber criminals behind ransomware campaigns typically focus their attacks in wealthy countries and cities where people and businesses can afford to pay the ransom. In recent months, we’ve seen repeated attacks on specific verticals, most notably healthcare.
Spam is the most common method for distributing ransomware. It is generally spread using some form of social engineering; victims are tricked into downloading an e-mail attachment or clicking a link. Fake email messages might appear to be a note from a friend or colleague asking a user to check out an attached file, for example. Or, email might come from a trusted institution (such as a bank) asking you to perform a routine task. Sometimes, ransomware uses scare tactics such as claiming that the computer has been used for illegal activities to coerce victims. Once the user takes action, the malware installs itself on the system and begins encrypting files. It can happen in the blink of an eye with a single click.
Another common method for spreading ransomware is a software package known as an exploit kit. These packages are designed to identify vulnerabilities and exploit them to install ransomware. In this type of attack, hackers install code on a legitimate website that redirects computer users to a malicious site. Unlike the spam method, sometimes this approach requires no additional actions from the victim. This is referred to as a “drive-by download” attack.
Spam botnets and exploit kits are relatively easy to use, but require some level of technical proficiency. However, there are also options available for the aspiring hackers with minimal computer skills. According to McAfee, there are ransomware-as-a-service offerings hosted on the Tor network, allowing just about anyone to conduct these types of attacks.