Prevent crypto-mining malware with Darktrace. Learn how Monero-miner infections spread on networks. Stop cyber-criminals earning from illegal activities.
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.
Written by
Max Heinemeyer
Global Field CISO
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15
Apr 2018
Malware Trends
One of the top malware trends in recent months has been the stellar growth of crypto-mining malware. Of the various crypto-currencies, the most prominent malware used for illegal mining activities is Monero, a crypto-currency that can be profitably mined on commodity hardware such as laptops and workstations. Moreover, a related trend observed recently is that of laterally moving malware which, as its name suggests, moves between devices to execute its payloads in a variety of different ways. This malware, used in attacks such as WannaCry, NotPetya and BadRabbit, uses techniques such as encrypting hard drives with ransomware while also deploying Monero miners.
As Darktrace regularly detects crypto-mining attempts the moment they occur on a network, we can estimate the cash flow stream a cyber-criminal earned on a laterally moving Monero-miner infection that Darktrace identified.
Monero-miner Infection
Last month, a customer’s device – which we will call patient zero – became infected with a Monero-miner. After a short time, patient zero started looking for accessible SMB drives by scanning the internal network for devices on port 445. As the device had not conducted any network scanning activity in the past, Darktrace flagged the process as an unusual network scan and an anomalous SMB enumeration:
The network scan (device names are redacted)
Once patient zero identified accessible IPC$, ADMIN$ or C$ SMB drives, it transferred an executable to the drive. After the file transfer, the malware used PsExec to connect to the device and execute the malicious software. As patient zero had not made any SMB drive writes and had not used PsExec in this fashion before, alerts were raised immediately:
Lateral movement (device names are redacted)
Spread and containment of Monero-miner
The now-infected device started mining Monero and attempted to communicate over Tor2Web with Command & Control (C2) servers:
C2 traffic (device names are redacted)
Using Darktrace, the security team identified the infection within minutes and assessed the complete extent of the infection in less than an hour. Within three hours from initial detection, the security team had run a clean-up script on their network which stopped the spread.
Monero-miner Revenue estimates
We have estimated the hypothetical revenue for this particular attack. To make the mining less detectable, some of the current Monero-mining malware applies restrictions to both the number of threads that can be used and the maximum CPU usage capacity. As a result, we have estimated the figures below on a worst-case scenario basis.
We know that 300 machines were infected and that the Monero miners were running for around 4 hours.
Mining profitability is commonly measured in the amount of hashes calculated per second per CPU core or GPU. This number, known as hashes per second (H/S), can differ based on the hardware used. A common number on the lower end of the scale for H/S on a single CPU is 20 H/S for the CryptoNight algorithm used to mine Monero.
GPUs, being more efficient for the CryptoNight algorithm, can yield 2-3x the H/S rate of CPUs and beyond. Keeping with a worst-case scenario basis, we will assume all infected devices had only 2 CPU cores and no GPUs, meaning a single infected machine yielded 40 H/S. This leads us to the following calculation: 300 infected devices x 40 H/S = 12000 H/S.
A Monero-mining revenue calculation tool produced the following results: with a Monero price of $202.43 at the time of infection (disregarding electricity costs), the criminal would have earned roughly $15.85 in 24h. As the miners only ran for around 4 hours, the resulting revenue would have only been $2.64. So how is this profitable?
It’s a numbers game
Cryptocurrency-mining operations are designed to last for months, not hours. If this infection had gone undetected, the criminal would have earned $15.85 per day, or $475.62 per month. Furthermore, victims with larger networks are much less likely to notice the infection. As attacks spreading this kind of malware are often indiscriminate in nature, they will often hit thousands of organizations at the same time, giving them the capacity to generate much more than just half a dollar.
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.
“I wonder if running that tool influenced the connectivity in some way.”
“I might need to target down or reboot, but first, I'll investigate the network using ARP. I wonder if ARP is responding properly. If I see "ip neigh stale," that could indicate a problem. I think arping might help in this situation, but I’ll need to keep an eye on how the network is behaving. It's all about figuring out where the issue lies!”
図10：エージェントの異常なLDAPアクティビティに対してトリガーされたこのLinuxサーバーに対するモデル検知は、Cyber AI Analystによって自律的に調査され、その調査結果にはエージェントの異常なSMBセッションアクティビティに関する内容が含まれ、Cyber AIAnalystインシデントに記録されました。
DarktraceのCyber AI Analystは、エージェントのアクティビティによってトリガーされたモデル検知を自律的に調査し、その調査結果を1つの重要なインシデントレポートにまとめました。インシデント報告書の内容は、エージェントによるネットワークスキャンから始まりコーディング演習内容のSMBベースの上書きで終わる、エージェントの行動の各段階を詳しくカバーしています。
図20：Cyber AI Analystは、モデル検知に対する自律的な調査を通じて得られた所見をつなぎ合わせ、エージェントの進行状況のタイムラインを作成し、アクティビティを視覚的に表したグラフとともに提供しました。
Cyber Verification Program下のAnthropic Opus 4.6モデルなど、他のフロンティアモデルを使用したエージェントも、Darktraceのシミュレートされた環境で同じ設定とタスクを使ってテストされました。反復の度に、エージェントは演習の内容または採点プログラムを変更して不正を行おうとしました。基盤となるモデルに関係なく、エージェントは自分が置かれた環境を侵害することで、100％のスコアを達成する方法を見つけることに成功していました。これらのエージェントによるハッキングは、アクティビティの内容こそ違っていましたが、すべてその環境のベースラインの振る舞いから大きく逸脱した動作を引き起こしていました。これらの逸脱はDarktraceプラットフォームに十分な検知の機会を提供し、エージェントの逃げ場はありませんでした。
エージェンティックハーネスは会話履歴をローカルに保存しますが、ダークトレースの研究者たちは、保存されたAIの応答が本当にモデルによって生成されたものであるかどうかの検証が行われていないことを発見しました。また、この設計上の選択がAnthropic Claude Code、AWS Kiro-CLI、OpenAI Codex、およびオープンソースのPiにわたって共通していることを確認しました。
会話履歴は多くの場合クライアント側に保存されます。例えば、Anthropic Claude Code、OpenAI Codex、AWS Kiro-CLI、Piなどでもそうです。そのため、ユーザーはセッションを自由に再開でき、一部の製品にはその履歴を操作する機能が組み込まれています。たとえば、会話の中の特定の時点に戻り、送信したメッセージを編集して、会話を別の軌道へ進めていくことができます。きわめて重要な点として、私たちが調査したすべてのケースにおいて、保存されているAIの応答が対応するモデルから生成されたものであり改ざんされていないことの検証は行われていませんでした。
