Ransomware is a sophisticated piece of malware that blocks the victim’s access to his/her files, and the only way to regain access to the files is to pay a ransom.
May 12th 2017 saw the biggest ever cyber attack in Internet history (yes, bigger than the Dyn DDoS). A ransomware named WannaCry stormed through the web, with the damage epicenter being in Europe.
WannaCry leveraged a vulnerability in Windows OS, first discovered by the NSA, and then publicly revealed to the world by the Shadow Brokers. In the first few hours, 200,000 machines were infected. Big organizations such as Renault or the NHS were struck and crippled by the attack.
Ransomware has been a growing trend for the past two years, and this is just a culmination, a grand reveal to the wider world of just how big of a threat it is.
This scenario is unfolding right now somewhere in the world. Maybe even in your city or neighborhood.
In this very moment, someone is clicking a link in a spam email or activating macros in a malicious document.
In a few seconds, all their data will be encrypted and they’ll have just a few days to pay hundreds of dollars to get it back. Unless they have a backup, which most people don’t.
Ransomware creators and other cyber criminals involved in the malware economy are remorseless. They’ve automated their attacks to the point of targeting anyone and everyone.
There are two types of ransomware in circulation:
Encryptors, which incorporates advanced encryption algorithms. It’s designed to block system files and demand payment to provide the victim with the key that can decrypt the blocked content. Examples include CryptoLocker, Locky, CrytpoWall and more.
Lockers, which locks the victim out of the operating system, making it impossible to access the desktop and any apps or files. The files are not encrypted in this case, but the attackers still ask for a ransom to unlock the infected computer. Examples include the police-themed ransomware or Winlocker.
Some locker versions infect theMaster Boot Record (MBR). The MBR is the section of a PC’s hard drive which enables the operating system to boot up. When MBR ransomware strikes, the boot process can’t complete as usual and prompts a ransom note to be displayed on the screen. Examples include Satana and Petya families.
Crypto-ransomware, as encryptors are usually known, are the most widespread ones, and also the subject of this article. The cyber security community agrees that this is the most prominent and worrisome cyber threat of the moment.
Ransomware has some key characteristics that set it apart from other malware:
It feature sunbreakable encryption, which means that you can’t decrypt the files on your own (there are various decryption tools released by cyber security researchers – more on that later);
It has the ability to encrypt all kinds of files, from documents to pictures, videos, audio files and other things you may have on your PC;
It can scramble your file names, so you can’t know which data was affected. This is one of the social engineering tricks used to confuse and coerce victims into paying the ransom;
It will add a different extension to your files, to sometimes signal a specific type of ransomware strain;
It will display an image or a message that lets you know your data has been encrypted and that you have to pay a specific sum of money to get it back;
It requests payment in Bitcoins because this crypto-currency cannot be tracked by cyber security researchers or law enforcements agencies;
Usually, the ransom payments have a time-limit, to add another level of psychological constraint to this extortion scheme. Going over the deadline typically means that the ransom will increase, but it can also mean that the data will be destroyed and lost forever.
It uses a complex set of evasion techniques to go undetected by traditional antivirus (more on this in the “Why ransomware often goes undetected by antivirus” section);
It often recruits the infected PCs into botnets, so cyber criminals can expand their infrastructure and fuel future attacks;
It can spread to other PCs connected to a local network, creating further damage;
It frequently features data exfiltration capabilities, which means that it can also extract data from the affected computer (usernames, passwords, email addresses, etc.) and send it to a server controlled by cyber criminals; encrypting files isn’t always the endgame.
It sometimes includes geographical targeting, meaning the ransom note is translated into the victim’s language, to increase the chances for the ransom to be paid.
How do ransomware threats spread?
Cyber criminals simply look for the easiest way to infect a system or network and use that backdoor to spread the malicious content.
Nevertheless, these are the most common infection methods used by cybercriminals
Self-propagation (spreading from one infected computer to another); WannaCry, for instance, used an exploit kit that scanned a user’s PC, looking for a certain vulnerability, and then launched a ransomware attack that targeted it.
Affiliate schemes in ransomware-as-a-service. Basically, the developer behind the ransomware earns a cut of the profits each time a user pays the ransom.
How do ransomware infections happen?
Though the infection phase is slightly different for each ransomware version, the key stages are the following:
Initially, the victim receives an email which includes a malicious link or a malware-laden attachment. Alternatively, the infection can originate from a malicious website that delivers a security exploit to create a backdoor on the victim’s PC by using a vulnerable software from the system.
If the victim clicks on the link or downloads and opens the attachment, a downloader (payload) will be placed on the affected PC.
The downloader uses a list of domains or C&C servers controlled by cyber criminals to download the ransomware program on the system.
The contacted C&C server responds by sending back the requested data.
The malware then encrypts the entire hard disk content, personal files, and sensitive information. Everything, including data stored in cloud accounts (Google Drive, Dropbox) synced on the PC. It can also encrypt data on other computers connected to the local network.
A warning pops up on the screen with instructions on how to pay for the decryption key.
Everything happens in just a few seconds, so victims are completely dumbstruck as they stare at the ransom note in disbelief. Most of them feel betrayed because they can’t seem to understand one thing.
15 Items to take your ransomware protection to the next level
The Dropbox/Google Drive/OneDrive/etc. application on your computer should not be left on by default. Open them once a day, to sync your data, and close them once this is done.
Your operating system and the software you use should be up to date, including the latest security updates.
For daily use, don’t use an administrator account on your computer. Use a guest account with limited privileges.
Turn off macros in the Microsoft Office suite – Word, Excel, PowerPoint, etc.
Remove the following plugins from your browsers: Adobe Flash, Adobe Reader, Java and Silverlight. If you absolutely have to use them, set the browser “to ask me” if you want to activate these plugins when needed.