Carbon Black discovers evolution of popular cryptomining campaign

Endpoint protection solutions provider Carbon Black recently released a threat report outlining how a well-known cryptomining campaign has been enhanced to steal system access information for possible sale on the dark web.

Dubbed "Access Mining" by Carbon Black researchers, this particular attack stands to affect more than 500,000 computers around the world.

The methods used could pave the way for more dangerous and far-reaching attacks as threats considered lower priority can open the door for more advanced, targeted attacks that can be sold to the highest bidder.

The discovery was made after the CB ThreatSight team alerted Carbon Black's TAU about unusual behaviour seen across a handful of endpoints.

The ensuing investigation revealed sophisticated, multi-stage malware that was sending detailed system metadata to a network of hijacked web servers, presumably for the purposes of resale on one (or many) remote access marketplaces across the dark web.

Carbon Black TAU researchers Greg Foss and Marina Liang presented their research in a report Access Mining: How a Prominent Cryptomining Botnet is Paving the Way for a Lucrative and Illicit Revenue Model.

"Access Mining is a tactic where an attacker leverages the footprint and distribution of commodity malware, in this case, a cryptominer, using it to mask a hidden agenda of selling system access to targeted machines on the dark web," the researchers say.

"This discovery indicates a bigger trend of commodity malware evolving to mask a darker purpose and will likely catalyse a change in the way cybersecurity professionals classify, investigate and protect themselves from threats.

The report's key findings include:

At least 500,000 machines affected
60% of victims derived from the Asia Pacific region, and the rest from Russia and Eastern Europe.

Threat actors are increasingly using repurposed tools, modified exploits and stolen infrastructure
In previous campaigns, this threat actor used a modified version of XMRig to perform Monero mining.
In addition to the modified XMRig, our research showed that the group now uses readily available malware and open source tooling, such as Mimikatz and EternalBlue, which have been modified for purposes to pivot from infected systems and expand their campaign's reach.

Newly uncovered link between Smominru and MyKings
This investigation highlights an unexpected link between Smominru cryptomining campaign and the MyKings botnet, which is outlined in the full report.

Rapid evolution thanks to open source exploits
Modified versions of Cacls, XMRig and EternalBlue were used in this campaign. Obtaining the bulk of the code via open source sites like GitHub likely sped up the innovation to Access Mining, the researchers found.

Combining commodity malware with access-for-sale is lucrative at scale
The business model for Access Mining typically combines a profit stream from cryptomining with a profit stream from selling system access. Both can be highly lucrative (from some estimates on the latest discoveries, profit can be as much as $1.6 million annually) if done at scale.

"This discovery demonstrates how virtually any company could be leveraged in a targeted attack—even if that company lacks a worldwide brand, known intellectual property assets, or a Fortune 1000 listing," the researchers say.

"Access Mining represents a scalable and economical approach for an adversary to find valuable targets.