Blog

Crypto

Threat Finds

Inside the SOC

Crypto-mining on a DNS server

Crypto-mining on a DNS serverDefault blog imageDefault blog image
22
Jun 2021
22
Jun 2021

The rise of crypto-currencies has fuelled cyber-crime in various ways. Bitcoin has facilitated a range of criminal activities from money laundering to ransomware payments since its release in 2009, leading to a spike in ransomware attacks which has been growing ever since.

More directly, cyber-criminals often hack into company servers and exploit their processing power to mine cryptocurrency, without the organization’s knowledge. This blog will explore a real-life attack where an Internet-facing server was compromised and started mining Monero coins.

Mining cryptocurrency on an Internet-facing server

At a small private company in the APAC region, an Internet-facing DNS server began to receive multiple incoming RDP connections. They all came from rare destinations which had never been seen on the network. Many were sent from external sources with the RDP cookie, ‘hello’, indicating a brute-force attack.

Figure 1: Timeline of the attack

Hours later, the device was seen connecting out to a known endpoint associated with crypto-mining.

As both RDP and SMB ports on the device were open to the Internet, anomalous SMB connections were seen as well shortly following the crypto-mining connections.

Open ports, open sesame

Internet-facing servers are subject to many external threats, especially if sensitive ports are exposed. In this case, the attacker was able to gain a foothold through the DNS server because both the RDP and SMB ports could receive connections. It is important therefore to close communication to all external points which do not strictly need to be open.

Crypto-jacking continues to be a viable way for attackers to expend company resources in order to speed up their mining operations. Especially with the popularity of cryptocurrencies at the moment, we have observed a significant uptick in these types of threat.

The connections to the mining pool were identified by Darktrace’s AI without relying on any known IoCs. Instead, Cyber AI recognized the anomalous nature of the external endpoints, which were statistically rare for the server’s ‘pattern of life’.

If the threat had not been detected, the attacker would have continued to abuse the server resources, resulting in latency issues for important processes. The server could also have been subject to further malicious activity such as DDoS or ransomware.

Figure 2: A similar incident showing an increase in model breaches around the time of compromise on June 8

Protecting a company’s gems

Crypto-mining is notoriously difficult to detect and can go on for months unnoticed. And it can form just one phase of an attacker’s full plan to infiltrate a network — alongside moving laterally and compromising additional devices. Open ports and siloed defenses pave the way for an attacker to break into a system with little resistance.

Organizations need a mechanism for detecting unusual and sinister behavior once the threat is inside. To this end, Darktrace’s evolving understanding of ‘normal’ across users, devices, and peer groups enables it to detect the subtle signs of latent threats. And with Autonomous Response, it responds at machine speed, neutralizing the threat before it has had the chance to spread.

In this case, with Darktrace’s SOC team, the client was immediately made aware of the activity and promptly took the device offline. A Proactive Threat Notification was sent as soon as the attacker had commenced mining. Darktrace analysts then worked through the issue with the customer until the crisis had been resolved.

Darktrace’s AI detects and responds to threats no matter where they come from – RDP account compromise, misconfigured Internet-facing server, or sophisticated Hafnium-style zero day. Furthermore, it provides much-needed visibility over the enterprise, identifying and highlighting Internet-facing devices and any issues they may pose.

Thanks to Darktrace analyst Taylor Breland for his insights on the above threat find.

Learn more about illegal crypto-mining

Darktrace model detections:

  • Device / Anomalous RDP Followed By Multiple Model Breaches
  • Compromise / Monero Mining
  • Compromise / High Priority Crypto Currency Mining (Enhanced Model Breach/PTN)
  • Device / Anomalous SMB Followed By Multiple Model Breaches
  • Compliance / Crypto Currency Mining Activity
  • Anomalous Server Activity / Anomalous External Activity from Critical Network Device
  • Compliance / Incoming Remote Desktop
  • Compliance / Internet Facing RDP Server

Like this and want more?

Receive the latest blog in your inbox
Thank you! Your submission has been received!
Oops! Something went wrong while submitting the form.
INSIDE THE SOC
Darktrace cyber analysts are world-class experts in threat intelligence, threat hunting and incident response, and provide 24/7 SOC support to thousands of Darktrace customers around the globe. Inside the SOC is exclusively authored by these experts, providing analysis of cyber incidents and threat trends, based on real-world experience in the field.
AUTHOR
ABOUT ThE AUTHOR
Oakley Cox
Analyst Technical Director, APAC

Oakley is a technical expert with 5 years’ experience as a Cyber Analyst. After leading a team of Cyber Analysts at the Cambridge headquarters, he relocated to New Zealand and now oversees the defense of critical infrastructure and industrial control systems across the APAC region. His research into cyber-physical security has been published by Cyber Security journals and CISA. Oakley is GIAC certified in Response and Industrial Defense (GRID), and has a Doctorate (PhD) from the University of Oxford.

COre coverage
This Article
Crypto-mining on a DNS server
Share
Twitter logoLinkedIn logo

Good news for your business.
Bad news for the bad guys.

Start your free trial

Start your free trial

Flexible delivery
You can either install it virtually or with hardware.
Fast install
Just 1 hour to set up – and even less for an email security trial.
Choose your journey
Try out Self-Learning AI wherever you most need it — including cloud, network or email.
No commitment
Full access to the Darktrace Threat Visualizer and three bespoke Threat Reports, with no obligation to purchase.
Thank you! Your submission has been received!
Oops! Something went wrong while submitting the form.

Get a demo

Flexible delivery
You can either install it virtually or with hardware.
Fast install
Just 1 hour to set up – and even less for an email security trial.
Choose your journey
Try out Self-Learning AI wherever you most need it — including cloud, network or email.
No commitment
Full access to the Darktrace Threat Visualizer and three bespoke Threat Reports, with no obligation to purchase.
Thank you! Your submission has been received!
Oops! Something went wrong while submitting the form.