The Dharma Boom: how works shy, but most successful ransomware of recent yearsRecently, names of ransomware related to high-profile hacks of large companies, theft of personal information of celebrities and politicians, and multimillion-dollar ransom demands have been popular on resources devoted to information security. Examples include Maze, ReVIL/Sodinokibi, and WastedLocker. However, the most successful service in this area is not them, but the ransomware Dharma, which is spreading on underground forums by the ransomware as a service (RaaS) business model.
Introduced in 2016, Dharma is truly one of the most profitable ransomware programs today due to its service business model. This is supported by studies like “Color by numbers: Inside a Dharma RaaS attack” from Sophos and Covewar publications.
McDonald’s of cybercriminal underworld
The researchers write that Dharma can be compared to a franchise for a fast-food enterprise like McDonald’s since the malware can be purchased and used by anyone, who can follow criminal instructions on how to cause the most damage.
Ease of use is at the heart of the Dharma RaaS business model. Clients are offered a package of scripts and tools that do not require special technical skills to use.
The subscription price for the service is $2 thousand. Customers do the dirty work themselves – they hack into the enterprise network and install ransomware, while the service operators receive passive income.
A Brief History of the Dharma
The ransomware was originally launched under the name CrySiS in the summer of 2016.
CrySis was a so-called ransomware-as-a-service (RaaS) operation. The author of CrySiS created a service where clients (other criminal groups) could create their own versions of the ransomware to distribute to victims – usually through spam campaigns, exploit kits, or brute force attacks on RDP endpoints.
After someone leaked the CrySiS master decryption keys in November 2016, CrySiS RaaS was relaunched two weeks later under the name Dharma.
Some Dharma decryption keys, however, also leaked to the network in March 2017, but Dharma operators did not rebrand this time and continued to work without interruption, turning their RaaS into one of the largest ready-made solutions for ransomware in the underworld.
Over the years, there has been a constant stream of new versions of the Dharma. The ransomware received updates, new customers signed up to distribute it, and many unique variations of the Dharma were spread throughout the world.
With the updates of criminal underground in 2018 and 2019 – from the massive spread of ransomware (via email spam) to targeted attacks (on corporate networks) – the Dharma also has changed.
In the spring of 2019, on the network appeared a new strain called Phobos, which is used mainly for targeted attacks. Security researchers at Coveware and Malwarebytes immediately noted that Phobos is almost identical to Dharma.
Nevertheless, the “good old” Dharma did not rest after the release of Phobos either.
Jakub Kroustek, head of threat intelligence at Avast, only discovered three new versions of Dharma in the spring of 2020, which means that criminal groups still believe the Dharma code to be reliable and continue to use it even now, more than three years after its launch.
John Fokker, head of cyber investigations at McAfee, told ZDNet that the Dharma code has been circulating in the hacker underground for quite some time and is only now emerging on quite open forums: for example, in March 2020, the source code of one of the ransomware versions was put for sale on a Russian-speaking hacker forum.
Gillespie, who has released dozens of ransomware decryptors in the past and even received an FBI award for his efforts, told ZDNet that he had been unable to find decryption flaws in Dharma.
Dharma Epidemic Mechanism
Due to its accessibility, Dharma has become the center of a criminal ecosystem based on the “syndication” business model. Dharma RaaS vendors offer their technical expertise and support by managing internal systems that support ransomware attacks.
Affiliates (often entry-level cybercriminals) pay to use RaaS and conduct targeted attacks themselves using a standard set of tools. Other actors provide stolen credentials and other tools on criminal forums that allow attacking the Remote Desktop Protocol, which is the predominant initial hacking tool for Dharma subjects. (According to statistics provided by Coveware, RDP attacks are the main cause of approximately 85% of Dharma attacks.)
You can find some technical details in our previous Dharma review.
Over the past year, ransom demands from Dharma subjects were lower in comparison to other major types of targeted ransomware. In December 2019, when the average demand for ransomware rose to $191,000, the average Dharma ransom demand was only $8,620. This is partly due to the types of targets hit by the Dharma (mainly small and medium-sized businesses) and partly to the skills, experience and location of the attacking affiliates. Either way, Dharma operators are mitigate lower ransomware demands by the number of victims, as Dharma remains one of the most profitable ransomware families, according to Coveware.
How to prevent Dharma infection
Most of these attacks from Dharma partners can be prevented by patching and securing RDP servers with VPN with multi-factor authentication. Organizations need to be vigilant against phishing credentials, especially as they adjust to new working settings, when more and more employees work remotely. In addition, is required attention to the access, provided to service providers and other third parties for business purposes.