There are four primary motivations for cyberattacks: crime, hacktivism, espionage and war. Setting aside nation-state sponsored groups, the largest faction of attackers are cybercriminals, individuals or well-established organizations looking to turn a profit.
For the last several years, ransom-based cyberattacks and ransomware had been the financial modus operandi for hackers, but 2018 flipped the coin to unveil a new attack vector: cryptomining.
Radware’s Malware Threat Research Group monitored this phenomenon throughout the year and identified two recurring trends. Some groups use cryptomining to score a quick, easy profit by infecting machines and mining cryptocurrencies. Other groups use cryptomining as an ongoing source of income, simply by reselling installations on infected machines or selling harvested data.
While there is no definitive reason why cryptomining has become popular, what is clear are some of the advantages it has over older attacks methods:
- It’s easy – There’s no need to develop a cryptomining tool or even buy one. An attacker can just download a free tool into the victim’s machine and run it with a simple configuration that instructs it to mine the pool.
- CPU – While Bitcoin requires a graphic processing unit (GPU) to perform effective mining, other cryptocurrency, such as Monero, require only CPU to effectively mine a machine. Since every machine has a CPU, including web cameras, smartphones, smart TVs and computers, there many potential targets.
- Minimal footprint — Other attack types require the hackers to market their “goods” or to actively use the information they acquired for malicious purposes. In cryptomining, the money moves directly to the attacker.
- Value — The value of cryptocurrencies skyrocketed in late 2017 and early 2018. The outbreak quickly followed. More recently, as monetary value declined, so has the number of incidences.
- Multipurpose hack — After successfully infecting a machine, hackers can leverage the installation of the malware program for multiple activities. Stealing credentials from machines? Why not use those machines to cryptomine as well (and vice versa)? Selling data mining installations on machines to other people? Add a cryptomining tool to run at the same time.
The Malware Ecosystem
There are a few popular ways for cybercriminals to launch cryptomining attacks:
- Information stealing — By distributing a data harvesting malware, attackers steal access credentials or files (photos, documents, etc.), and even identities found on an infected machine, its browser or inside the network. Then, the cybercriminals generally use the stolen data to steal. In the case of bank credentials, the hackers use the information to steal money from accounts. They may also sell the stolen data through an underground market on the dark web to other hackers. Credit cards, social security numbers and medical records go for just a few dollars. Social media accounts and identities are popular, as well. Facebook and Instagram accounts have been hijacked and used for propagation.
- Downloaders — Malware is distributed with simple capabilities to download additional malware and install on other systems.The motivation is to infect as many machines as possible. The next step is to sell malware installations on those machines. Apparently, even infected machines enjoy brand premium fees — machines from a Fortune 500 company cost a lot more.
- Ransomware — Machines are infected with a malware that encrypts files, which are usually valuable to the victim, such as photos, Microsoft files (.xlsx,.docx) and Adobe Acrobat files. Victims are then asked to pay a significant amount of money in order to get a tool to decrypt their files. This attack was first introduced against individuals but grew exponentially when hackers figured out that organizations can pay a higher premium.
- DDoS for ransom (RDoS) — Attackers send targets a letter that threatens a DDoS attack on a certain day and time unless the organization makes a payment, usually via Bitcoin. Often hackers know the IP address of the targeted server or network and launch a small-scale attack as a preview of what could follow.
Malware protection is a mature market with many competitors. It is a challenge for hackers to create a one-size-fits-all zero-day attack that will run on as many operating systems, servers and endpoints as possible, as well as bypass most, if not all, security solutions. So in addition to seeking ways to penetrate protection engines, hackers are also looking for ways to bypass them.
During the past year, Radware noticed several campaigns where malware was created to hijack social network credentials. That enabled hackers to spread across the social network accessing legitimate files on the machine and private information (or computing resources, in the context of cryptomining).
Here are a few examples:
- Nigelthorn – Radware first detected this campaign, which involved a malicious chrome extension, in a customer’s network. The hackers bypassed Google Chrome native security mechanisms to disguise the malware as a legitimate extension. The group managed to infect more than 100,000 machines. The purpose of the extension was cryptomining Monero currency by the host machine, as well as stealing the credentials of the victim’s Facebook and/or Instagram accounts. The credentials were abused to propagate the attack through the Facebook user’s contact network. It is also possible that the credentials were later sold on the black market.
- Stresspaint — In this spree, hackers used a benign-looking drawing application to hijack Facebook users’ cookies. They deceived victims by using an allegedly legitimate AOL.net URL, which was actually a unicode representation. The true address is “xn--80a2a18a.net.” The attackers were building a database of users with their contact
network, business pages and payment details. Radware suspects that the ultimate goal was to use this information to fund public opinion influence campaigns on the social network.
- CodeFork — This campaign was also detected in some of Radware’s customers’ networks when the infected machines tried to communicate with their C&C servers. Radware intercepted the communication and determined that this group was infecting machines in order to sell their installations. The group has been active for several years during which time we have seen them distributing different malware to the infected machines. The 2018 attack included an enhancement that distributes
Radware believes that the cryptomining trend will persist in 2019. The motivation of financial gain will continue, pushing attackers to try to profit from malicious malware. In addition, hackers of all types can potentially add cryptomining capabilities to the infected machines that they already control. Our concern is that during the next phase, hackers will invest their profits to leverage machine-learning capabilities to find ways to access and exploit resources in networks and applications.