Cryptojacking – the use of remote computing power to mine cryptocurrency – wasn’t always a threat. Just a few months ago, online news outlets openly declared their intention to use the computing power of site visitors to generate Bitcoin, Ethereum, Monero, and other cryptocurrencies as a way to replace lost ad revenue. The incentive is there too; given that Bitcoin mining generates about 12.5 BTC every 10 minutes, or over $80,000 at today’s value, that’s about $4.2bn a year.
Now there are stories of entire networks slowing to a crawl as malware mines in the background, devices catching fire because their CPUs are overtaxed, and gaming software serving as a cover for cryptocurrency scams.
The Role of DNS in Cryptojacking
Most filters, firewalls, and ad blockers have been reprogrammed to stop common cryptomining malware and browser extensions like Coinhive. Unfortunately, this hasn’t done much to stop the spread of cryptomining on mobile and other IoT devices, many of which are easily compromised through hard-coded credentials and the use of unsecured public networks.
Finding and eliminating the source of cryptojacking can be difficult – it can be hiding just about anywhere on the network. Yet all cryptojacking attempts do have one thing in common: they have to communicate out.
DNS may be the most reliable way to detect and eliminate cryptojacking at an enterprise level. Filters, firewalls, and ad blockers can stop some communication with remote servers or identify malicious payloads, but often lack insight into the source IP and are unable to deal with infected IoT devices.
With a client-facing DNS security system like DNS Edge, cryptojacking can be easily traced to a source device in real-time and blocked until the device has been cleansed. Perhaps just as importantly, DNS Edge can monitor those devices after remediation to ensure that the malicious activity has stopped.
Mitigating Cryptojacking on a Customer Network
DNS Edge recently helped a BlueCat customer discover and remediate wide-scale cryptojacking on its network. After installing DNS Edge, the customer was able to quickly identify multiple DNS queries of sites associated with known crytojacking software such as Coinhive and Coinimp. The mining operations were highly coordinated and targeted, occurring largely at times of day where use of computing resources were low and the activity was less likely to be discovered.
The customer’s existing firewall settings were able to treat the symptoms of cryptojacking, but not eliminate the underlying problem. The firewall effectively blocked execution of the cryptomining results back to the remote server based on blacklists applied to payload data. Yet the firewall failed to block DNS-based command and control functions, and was unable to identify the source IP of infected devices. The clients were still infected and using up valuable computing resources, even if the results of that compute weren’t making it to the outside internet.
With the comprehensive client-facing logs produced by DNS Edge, the customer was able to quickly associate cryptojacking activity with individual devices and direct its remediation activity accordingly. With the security policy functions of DNS Edge, the customer will be able to disrupt the full range of communication between the cryptojacking software and remote servers.
Staying One Step Ahead
The presence of multiple layers of cryptojacking on the customer network suggests that this is an evolving threat in which malicious actors will use a variety of methods to infiltrate and exploit large networks. Thankfully, the ubiquitous nature of DNS and its central role in exfiltration of cryptomining data allows DNS Edge to quickly identify and mitigate against this growing threat.
Learn more about how to make DNS your first line of defense here.