OXFORD, U.K.  — décembre 2, 2021 —

Sophos, a global leader in next-generation cybersecurity, today released new findings on the Tor2Mine cryptominer, “Two flavors of Tor2Mine miner dig deep into networks with PowerShell, VBScript,” that show how the miner evades detection, spreads automatically through a target network and is increasingly harder to remove from an infected system. Tor2Mine is a Monero-miner that has been active for at least two years.

In the research, Sophos describes new variants of the miner that include a PowerShell script that attempts to disable malware protection, execute the miner payload and steal Windows administrator credentials. What happens next depends on whether the attackers successfully gain administrative privileges with the stolen credentials. This process is the same for all the variants analyzed.

For example, if the attackers manage to get hold of administrative credentials, they can secure the privileged access they need to install the mining files. They can also search the network for other machines on which they can install the mining files. This enables Tor2Mine to spread further and embed itself on computers across the network.

If the attackers cannot gain administrative privileges, Tor2Mine can still execute the miner remotely and filelessly by using commands that are run as scheduled tasks. In this instance, the mining software is stored remotely rather than on a compromised machine.

The variants all attempt to shut down anti-malware protection and install the same miner code. Similarly, in all cases, the miner will continue to re-infect systems on the network unless it encounters malware protection or is completely eradicated from the network.

“The presence of miners, like Tor2Mine, in a network is almost always a harbinger of other, potentially more dangerous intrusions. However, Tor2Mine is much more aggressive than other miners,” said Sean Gallagher, senior threat researcher at Sophos. “Once it has established a foothold on a network, it is difficult to root out without the assistance of endpoint protection software and other anti-malware measures. Because it spreads laterally away from the initial point of compromise, it can’t be eliminated just by patching and cleaning one system. The miner will continually attempt to re-infect other systems on the network, even after the command-and-control server for the miner has been blocked or goes offline. As cryptocurrencies continue to increase in value and support the ever-growing ransomware and cyberextortion landscape, we may well see more, and more aggressive, variants of other cryptominers emerge.”

Sophos researchers also discovered scripts designed to kill off a variety of processes and tasks. Almost all of them are related to crimeware, including competing cryptominers and clipper malware that steals cryptocurrency wallet addresses.

“Miners are a low-risk way for cybercriminals to turn a vulnerability into digital cash, with the greatest risk to their cash flow being competing miners discovering the same vulnerable servers,” said Gallagher.

Sophos recommends the following to help organizations protect their networks and endpoints against cryptominers such as Tor2Mine:

  1. Patch software vulnerabilities quickly on internet-facing systems, such as web applications, VPN services and email servers, as this will make them far less likely to fall victim to cryptominers
  2. Install anti-malware products – miners are usually easily detected by such technologies – particularly those that leverage Windows’ Anti-Malware Software Interface (AMSI) to spot scripts intended to shut down malware protection
  3. Monitor for unusually heavy use of processing power, reduced computer performance and higher than expected electricity bills, as any of these can indicate the presence of cryptominers on the network

Sophos detects Tor2Mine variants as the MineJob family (MineJob-A through E) and detects the script behaviors of each variant.

Indicators of compromise for the Tor2Mine variants discussed in the research are available on SophosLabs’ GitHub page.

Learn more about the Sophos analysis of Tor2Mine at SophosLabs Uncut.

À propos de Sophos

Sophos est un leader mondial et un innovateur dans le domaine des solutions de cybersécurité avancées, qui comprend des services managés de détection et réponse (MDR) et de réponse aux incidents, ainsi qu’un vaste portefeuille de technologies de sécurité qui protègent les systèmes endpoint, les réseaux, les messageries et le Cloud contre les cyberattaques. Sophos est l’un des plus grands fournisseurs de cybersécurité et protège aujourd’hui plus de 500 000 entreprises et plus de 100 millions d’utilisateurs dans le monde contre les adversaires actifs, les ransomwares, le phishing, les malwares, etc. Les services et produits de Sophos sont connectés à travers sa console d’administration Sophos Central basée dans le Cloud et sont alimentés par Sophos X-Ops, l’unité de renseignement sur les menaces transversale de la société. L’intelligence de Sophos X-Ops optimise l’ensemble de l’écosystème de cybersécurité adaptatif (ACE) de Sophos, qui comprend un datalake centralisé exploitant un ensemble riche d’API ouvertes à destination des clients, des partenaires, des développeurs et des autres fournisseurs de cybersécurité et de technologies de l’information. Sophos fournit des services de cybersécurité aux entreprises qui ont besoin de solutions de sécurité clés en main et entièrement gérées. Les clients peuvent également gérer leur cybersécurité directement avec la plateforme d’opérations de sécurité de Sophos ou utiliser une approche hybride en complétant leurs équipes internes avec les services de Sophos, notamment la chasse aux menaces et la remédiation. Sophos vend ses produits par l’intermédiaire d’un réseau mondial de partenaires et de fournisseurs de services gérés (MSP : Managed Service Provider). Le siège de l’entreprise est basé à Oxford, au Royaume-Uni. Plus d’informations sont disponibles sur www.sophos.fr.