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Inside the SOC

リモートアクセスツールの危険性を探る

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03
Aug 2022
03
Aug 2022
This discursive blog explores the use of remote access tools in exploitations across OT/ICS and corporate environments. Whether restricted or supported, remote access tools are shown to benefit from the Darktrace product suite, including our DETECT, RESPOND and PREVENT product families.

2022年、リモートアクセスツールは、組織に多目的なサポートを提供し続けています。世界中からデバイスを遠隔操作することで、ITチームは対応コストや移動時間を節約し、契約社員などの外部関係者からリモートサポートを受けることができます[1 & 2]。これは、物理的なアクセスが制限されることのあるOT/ICSシステムのような特殊なマシンが関係する場合に特に関連性が高くなります。しかし、これらのツールには、それなりのリスクが伴います。このブログでは、Darktrace の顧客から寄せられた2つの事例をもとに、これらのリスクとその対処法(特にOT環境におけるリスク)について説明します。 

最も人気のあるリモートツールの1つが、デスクトップと携帯端末の両方で使用できる包括的なビデオ会議およびリモート管理ツールであるTeamViewerです[3]。他の高度なツールと同様、意図したとおりに動作すると、まるで魔法のように見えることがあります。しかし、リモートアクセスツールは悪用される可能性があり、潜在的な脅威者に特権的なネットワークアクセスを許可する可能性があります。TeamViewerは、加害者と被害者の両方のデバイスにインストールする必要がありますが、もし攻撃者が誤った設定のTeamViewerデバイスにアクセスすることができれば、足場を固めてマルウェアを展開することが容易になります。 

2021年初頭、米フロリダ州オールズマー市の浄水場[4]に対して、リモートアクセスツールの展開が新たなスケールで見られました(図1)。オールズマー市は、人口15,000人の都市の水中の化学物質濃度レベルを管理しています。この浄水場では、TeamViewerを使用して、従業員が画面を共有し、ITの問題を解決できるようにしていました。しかし2月、ある従業員がマウスカーソルを操作できなくなったことに気づきました。 当初は、カーソルを操作しているのは上司で、上司は定期的にコンピュータに接続して施設のシステムを監視しているのだと思い、気に留めていなかったそうです。しかし数時間後、この従業員は再びカーソルが勝手に動くのを目撃し、今度は水道の水酸化ナトリウムの濃度を変えようとしていることに気づいた(これは人間が飲むには非常に危険である)。ありがたいことに、この従業員はすぐにその変化に気づき、通常のレベルに戻すことができました。この出来事を振り返ったとき、関係者が投げかけた重要な疑問は、セキュリティスタックにおいて厳密にどこに脆弱性があったのか、ということでした。[5] その答えは不明確でした。

図1:フロリダ州における汚染水処理施設の写真 

攻撃者がネットワークに最初にアクセスしたとき、企業にとって最大の課題は、a) 機器の侵害が起こったこと、b) それがどのように起こったかを特定することです。これは、オールズマー市への攻撃で見られたのと同じ課題です。侵害の最初の物理的な兆候(カーソルの動き)が発生したとき、影響を受けたユーザーは、その活動が悪意のあるものであるかどうか、まだ確信が持てませんでした。Dragosによる詳細な調査により、水飲み場の存在、1か月前の偵察活動、Tofseeボットネットの標的型攻撃、2つの脅威が存在する可能性などが明らかになりました [6 & 7]。この2つの質問に対する答えは、複雑な攻撃であることを示唆していました。しかし、Darktraceを導入していれば、これらの疑問はあまり重要ではなくなります。 

Darktrace DETECT は、シグネチャに頼らず、AIベースのモデルで、これらのツールや広いネットワーク内の異常をライブで検知します。セキュリティの「穴」がどこかに関わらず、ライブでの検知により、セキュリティチームはほぼリアルタイムで対応できる可能性があります。

Darktraceの最高製品責任者であるMax Heinemeyerによると、オールズマー市での攻撃は、「クライアントが既に使用していた既製のツール、特にTeamViewerを悪用したもの」であったため、可能であったとのことです。ドメインコントローラを最初のベクトルとして狙うこの戦術は、マルウェアの展開を容易かつ効果的にしました。[8] 

Darktrace は、TeamViewerやリモートアクセスツールの異常な使用状況を可視化するために、複数のDETECT モデルを用意しています。

·      Compliance / Incoming Remote Access Tool

·      Compliance / Remote Management Tool On Client

·      Compliance / Remote Management Tool On Server

·      Device / Activity Identifier / Teamviewer 

一般的な受信特権接続:

·      Compliance / Incoming Remote Desktop

·      Compliance / Incoming SSH

Industrial DETECTでICS/OTシステムにおける新たなもしくは異常な変化を浮き彫りにすることもできます:

·      ICS / Incoming ICS Command

·      ICS / Incoming RDP And ICS Commands

·      ICS / Uncommon ICS Error

Darktrace は、セキュリティチームに事前対応の機会を与えるものであり、その機会を活用できるかどうかは、セキュリティチームにかかっています。当社のSOCチームは、ここ数か月の間にリモートアクセスコントロールが悪用され、注目を集めた脅威が発生したことを確認しています。一例を挙げると、Darktraceは、AnyDeskのインストールによってサポートされるランサムウェア攻撃を検知しました。 

5月、ある企業のメールサーバーが、PowerShellエージェント(6b79549200af33bf0322164f8a4d56a0fa08a5a62ab6a5c93a6eeef2065430ce )を使用して、異常なファイル '106.exe' に対する複数の外部リクエストを検知しました。一部のリクエストはシンクホールに誘導されましたが、それ以外の多くのリクエストは成功しました。その後、ハッシュ f126ce9014ee87de92e734c509e1b5ab71ffb2d5a8b27171da111f96f3ba0e75 (VirusTotal により悪意のあるものとしてマーク) が付いた DDL ファイルがダウンロードされました。この後、AnyDeskがインストールされましたが、これは、さらなる侵害の際にバックドア目的で展開されたと思われるリモートアクセスツールです。その後、脅威アクターは、新たにMimikatzを使用し、デフォルトのクレデンシャルを使用した大量のICMPおよびSMBv.1スキャンセッションを使用して、偵察に移行したことは明らかです。また、Netlogonサービスに対してDCE-RPCコールが行われており、2020年のZerologon脆弱性(CVE-2020-1472)[9] を悪用しようとした可能性が示唆されています。その後、顧客がLV(再利用されたREvil)に関連するランサムメモを発見すると、Darktrace のアナリストは、Darktrace RESPOND を人間による確認(human confirmation)モードではなくアクティブモードに再設定するのを支援しました(図2)。 

図2:お客様からお預かりしたLVのランサムノートのキャプチャ


この例では、このツールは最初のアクセスには使用されませんでしたが、お客様が進行中の侵害に対応しようとする際に、脅威アクターの持続性を確保するための重要な不測事態対応ツールであることに変わりはありません。しかし、Darktrace のモデル検知とRESPOND の設定変更によって提供される可視性によって、お客様はこの脅威アクターに対応し、攻撃の影響を軽減することができました。 

オールズマー市の実例を振り返ってみると、リモートアクセスツールを意識することは、戦いの半分に過ぎないことが分かります。さらに重要なことは、ほとんどの組織が、攻撃への利用をそもそも防ぐことができるのかどうかということです。既製のツールであるTeamViewerの使用を制限することは簡単な解決策のように思われますが、このようなツールは保守・サポート業務に不可欠な場合が多くあります。また、特権的なユーザーに限定した場合でも、これらのアカウントは潜在的に侵害される可能性があります。その代わりに、企業は大規模な視野を持ち、オールズマー市における攻撃が発生した環境を考慮することができます。 

このような背景から、OTとITの分離は、攻撃者がリスクのあるシステムにアクセスできなければ、そのシステムを攻撃することもできない、という解決策になり得るものです。しかし、ITとOTの融合やIoTデバイスの利用拡大に関する最近の議論に伴い、この分離を実現することはますます困難になっています [10]。複雑なネットワーク設計、厳しいパッチ適用要件、変化し続けるビジネス/運用ニーズはすべて、産業用セキュリティを確立する際の大きな考慮事項です。実際、TenableのCEOであるAmit Yoran氏は、オールズマー市に続いて分離を減らすことを奨励しています。「部品の故障や停止がいつ起こるかを予測できるように、それらを接続したいと考えるビジネス上の理由や効率上の理由があります(中略)」と述べています。[11] 

リモートアクセスの使用や産業用セットアップのいずれにも対処できない場合、セキュリティチームは、同様の攻撃を阻止するためにサードパーティのサポートに目を向ける必要があります。Darktrace DETECT に加え、弊社のDarktrace PREVENT とPREVENT/Attack Surface Management (ASM) は、リモートアクセス悪用の危険性があるインターネット接続デバイスをセキュリティチームに警告することができます。ASM は、企業の Web サイトや公開されているサーバーのオープンポートを Shodan API に積極的に照会します。これにより、この種のリモートアクセスに対して脆弱である可能性がある資産がハイライトされます。   

結論として、TeamViewerをはじめとするリモートアクセスツールは、セキュリティチームにとって多くの利便性をもたらすだけでなく、攻撃者にとっても利便性が高いと言えます。攻撃者は、産業用ネットワーク内のシステムを含む重要なシステムにリモートでアクセスし、リモートアクセスツールを梃子にマルウェアをインストールすることができます。セキュリティチームは、通常の許可された活動と、それを強制する方法の両方を知っておく必要があるのです。Darktrace DETECT では、ツールに透明性を与え、Darktrace RESPOND では、ツールをブロックすることができ、そして今、Darktrace PREVENT/ASM は、攻撃が起こる前にそのリスクを軽減するのに役立っています。プロフェッショナルの世界では、ハイブリッドワークの導入が進んでいるため、この種の製品を導入し、不要なリモートアクセスの危険から確実に保護することがますます重要になってきています。 

本ブログに寄稿したConnor Mooney氏に感謝します。

付録

参考文献 

[1] https://goabacus.com/advantages-and-disadvantages-of-remote-access-service/ 

[2] https://blog.ericom.com/advantages-of-remote-access/ 

[3] https://www.teamviewer.com/en/documents/ 

[4] https://www.wired.com/story/oldsmar-florida-water-utility-hack/ 

[5 & 11] https://www.bankinfosecurity.com/ot-it-integration-raises-risk-for-water-providers-experts-say-a-18841 

[6] https://www.dragos.com/blog/industry-news/a-new-water-watering-hole/ 

[7] https://www.dragos.com/blog/industry-news/recommendations-following-the-oldsmar-water-treatment-facility-cyber-attack/

[8] https://customerportal.darktrace.com/darktrace-blogs/get-blog/53  

[9] https://www.crowdstrike.com/blog/cve-2020-1472-zerologon-security-advisory/

[10] https://www.mckinsey.com/business-functions/operations/our-insights/converge-it-and-ot-to-turbocharge-business-operations-scaling-power

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.
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Dylan Hinz
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Gabriel Few-Wiegratz
Head of Threat Intelligence Hub
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Securing the cloud: Using business context to improve visibility and prioritize cyber risk

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26
Mar 2024

Why are businesses shifting to the cloud?

Businesses are increasingly migrating to cloud, due to its potential to streamline operations, reduce costs, and enhance scalability and flexibility. By shifting their infrastructure to the cloud, either as a whole or, more commonly in a hybrid model, organizations can access a wide array of services, such as storage, compute and software applications, without the need for extensive on-premises hardware. However, this transition isn't without challenges.  

Security challenges of cloud migration

Data security, compliance, integration with existing systems, and ensuring consistent performance are critical concerns that need to be addressed. Therefore, companies must develop robust oversight, implement comprehensive security measures, and invest in staff training to successfully navigate the transition to the cloud all while minimizing potential disruptions.

Implementing security measures within a company, however, is a complex endeavour that involves coordination among numerous internal stakeholders two of the most pivotal players involved in cloud security investment, are the security team, entrusted with crafting a business's defensive strategy, and the DevOps engineering team, architects of the infrastructure underpinning the organization's business operations.

Key questions to ask when securing the cloud

Which team is responsible for maintaining the application?  

What do they consider normal?  

How are potential misconfigurations increasing the potential risk of an incident?

Best practices of cloud security

Contextual awareness of the business is a crucial facet for securing a company's cloud infrastructure, as it enables organizations to align security measures with specific business objectives, risks, and regulatory requirements. Understanding the context of the business operations, its goals, critical assets, and compliance obligations, allows security teams to tailor their strategies and controls accordingly.

How does Darktrace help secure the cloud?

In response to the difficulties outlined above, Darktrace has adopted a holistic approach to security with an ActiveAI security platform that is context-aware. This platform enables stakeholders to effectively detect and respond to threats that may arise within their cloud or on premises environments.  

By monitoring your network and identity activity, Darktrace can identify what is considered “normal” within your organization. This however doesn’t tell the whole story. It is also important to understand where these actions are occurring within the context of the business.  

Visibility in the cloud

Without visibility into the individual assets that make up the cloud environment, how these are configured, and how they operate at run time, security is incredibly difficult to maintain. Visibility allows security teams to identify potential vulnerabilities, misconfigurations, or unauthorized access points that could be exploited by malicious actors. It enables proactive monitoring and rapid response to security incidents, ensuring that any threats are promptly identified and mitigated before they can cause significant damage.  

Building architecture diagrams

The cornerstone of our strategy lies in the architecture diagrams, which serve as a framework for organizing resources within our cloud environment. An architecture comprises of interconnected resources governed by access controls and network routing mechanisms. Its purpose is to logically group these resources into the applications they support.  

Achieving this involves compiling a comprehensive inventory of the cloud environment, analyzing resource permissions—including both outbound and inbound access—and considering any overarching organizational policies. For networked devices, we delve into route tables, firewalls, and subnet access control policies. This information is then utilized to build a graph of interconnected assets, wherein each resource constitutes a node, and the possible connections between resources are represented as edges.

Once we have built up an inventory of all the resources within your environments, we can then start building architectures based on the graph. We do this by selecting distinct starting points for graph traversal, which we infer from our deep understanding of the cloud, an example would be a Virtual Private Cloud (VPC) - A VPC is a virtual network that closely resembles a traditional network that you'd operate in your own data center.  

All networked devices are usually housed within a VPC, with applications typically grouped into one or more VPCs. If multiple VPCs are detected with peering connections between them, we consider them as distinct parts of the same system. This approach enables us to comprehend applications across regions and accounts, rather than solely from the isolated viewpoint of a single VPC.

However, the cloud isn’t all about compute instances, serverless is a popular architecture. In fact, for many developers serverless architectures offer greater scalability and flexibility. Reviewing prevalent serverless architecture patterns, we've chosen some common fundamental resources as our starting point, Lambda functions and Elastic Container Service (ECS) clusters are prime examples, serving as crucial components in various serverless systems with distinct yet similar characteristics.

Prioritize risk in the cloud

Once we have built up an inventory of all the cloud asset, Darktrace/Cloud utilizes an ‘outlier’ detection machine learning model. This looks to categorize all the assets and identifies the ones that look different or ‘odd’ when compared with the assets around it, this is based on a wide range of characteristics some of which will include, Name, VPC ID, Host Region etc, whilst also incorporating contextual knowledge of where these assets are found, and how they fit into the architecture they are in.  

Once outliers are identified, we can use this information to assess the potential risk posed by the asset. Context plays a crucial role in this stage, as incorporating observations about the asset enables effective scoring. For instance, detecting a misconfiguration, anomalous network connections, or unusual user activity can significantly raise the asset's score. Consequently, the architecture it belongs to can be flagged for further investigation.

Adapting to a dynamic cloud environment

The cloud is incredibly dynamic. Therefore, Darktrace does not see architectures as fixed entities. Instead, we're always on the lookout for changes, driven by user and service activity. This prompts us to dive back in, update our architectural view, and keep a living record of the cloud's ever-changing landscape, providing near real-time insights into what's happening within it.  

Darktrace/Cloud doesn’t just consider isolated detections, it identifies assets that have misconfigurations and anomalous activity across the network and management plane and adjusts the priority of the alerting to match the potential risk that these assets could be leveraged to enable an attack.  

While in isolation misconfigurations don’t have much meaningful impact, when they are combined with real time updates and anomaly detection within the context of the architecture you see a very important and impactful perspective.  

Combining all of this into one view where security and dev ops teams can collaborate ensures continuity across teams, playing a vital role in providing effective security.

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Adam Stevens
Analyst Technical Director

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Inside the SOC

Socks5Systemz: How Darktrace’s Anomaly Detection Unraveled a Stealthy Botnet

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22
Mar 2024

What are botnets?

Although not a recent addition to the threat landscape, botnets persist as a significant concern for organizations, with many threat actors utilizing them for political, strategic, or financial gain. Botnets pose a particularly persistent threat to security teams; even if one compromised device is detected, attackers will likely have infected multiple devices and can continue to operate. Moreover, threat actors are able to easily replace the malware communication channels between infected devices and their command-and-control (C2) servers, making it incredibly difficult to remove the infection.

Botnet example: Socks5Systemz

One example of a botnet recently investigated by the Darktrace Threat Research team is Socks5Systemz. Socks5Systemz is a proxy-for-rent botnet, whereby actors can rent blocks of infected devices to perform proxying services.  Between August and November 2023, Darktrace detected indicators of Socks5Systemz botnet compromise within a cross-industry section of the customer base. Although open-source intelligence (OSINT) research of the botnet only appeared in November 2023, the anomaly-based approach of Darktrace DETECT™ allowed it to identify multiple stages of the network-based activity on affected customer systems well before traditional rules and signatures would have been implemented.

Darktrace’s Cyber AI Analyst™ complemented DETECT’s successful identification of Socks5Systemz activity on customer networks, playing a pivotal role in piecing together the seemingly separate events that comprised the wider compromise. This allowed Darktrace to build a clearer picture of the attack, empowering its customers with full visibility over emerging incidents.

In the customer environments highlighted in this blog, Darktrace RESPOND™ was not configured to operate autonomously. As a result, Socks5Systemz attacks were able to advance through their kill chains until customer security teams acted upon Darktrace’s detections and began their remediation procedures.

What is Socks5Systemz?

The Socks5Systemz botnet is a proxy service where individuals can use infected devices as proxy servers.

These devices act as ‘middlemen’, forwarding connections from malicious actors on to their intended destination. As this additional connectivity conceals the true origin of the connections, threat actors often use botnets to increase their anonymity. Although unauthorized proxy servers on a corporate network may not appear at first glance to be a priority for organizations and their security teams, complicity in proxy botnets could result in reputational damage and significant financial losses.

Since it was first observed in the wild in 2016, the Socks5Systemz botnet has grown steadily, seemingly unnoticed by cyber security professionals, and has infected a reported 10,000 devices worldwide [1]. Cyber security researchers noted a high concentration of compromised devices in India, with lower concentrations of devices infected in the United States, Latin America, Australia and multiple European and African countries [2]. Renting sections of the Socks5Systemz botnet costs between 1 USD and 4,000 USD, with options to increase the threading and time-range of the rentals [2]. Due to the lack of affected devices in Russia, some threat researchers have concluded that the botnet’s operators are likely Russian [2].

Darktrace’s Coverage of Socks5Systemz

The Darktrace Threat Research team conducted investigations into campaign-like activity across the customer base between August and November 2023, where multiple indicators of compromise (IoCs) relating to the Socks5Systemz proxy botnet were observed. Darktrace identified several stages of the attack chain described in static malware analysis by external researchers. Darktrace was also able to uncover additional IoCs and stages of the Socks5Systemz attack chain that had not featured in external threat research.

Delivery and Execution

Prior research on Socks5Systemz notes how the malware is typically delivered via user input, with delivery methods including phishing emails, exploit kits, malicious ads, and trojanized executables downloaded from peer-to-peer (P2P) networks [1].

Threat actors have also used separate malware loaders such as PrivateLoader and Amadey deliver the Socks5Systemz payload. These loaders will drop executable files that are responsible for setting up persistence and injecting the proxy bot into the infected device’s memory [2]. Although evidence of initial payload delivery did not appear during its investigations, Darktrace did discover IoCs relating to PrivateLoader and Amadey on multiple customer networks. Such activity included HTTP POST requests using PHP to rare external IPs and HTTP connections with a referrer header field, indicative of a redirected connection.

However, additional adjacent activity that may suggest initial user execution and was observed during Darktrace’s investigations. For example, an infected device on one deployment made a HTTP GET request to a rare external domain with a “.fun” top-level domain (TLD) for a PDF file. The URI also appears to have contained a client ID. While this download and HTTP request likely corresponded to the gathering and transmission of further telemetry data and infection verification [2], the downloaded PDF file may have represented a malicious payload.

Advanced Search log details highlighting a device infected by Socks5Systemz downloading a suspicious PDF file.
Figure 1: Advanced Search log details highlighting a device infected by Socks5Systemz downloading a suspicious PDF file.

Establishing C2 Communication  

Once the proxy bot has been injected into the device’s memory, the malware attempts to contact servers owned by the botnet’s operators. Across several customer environments, Darktrace identified infected devices attempting to establish connections with such C2 servers. First, affected devices would make repeated HTTP GET requests over port 80 to rare external domains; these endpoints typically had “.ua” and “.ru” TLDs. The majority of these connection attempts were not preceded by a DNS host lookup, suggesting that the domains were already loaded in the device’s cache memory or hardcoded into the code of running processes.

Figure 2: Breach log data connections identifying repeated unusual HTTP connections over port 80 for domains without prior DNS host lookup.

While most initial HTTP GET requests across investigated incidents did not feature DNS host lookups, Darktrace did identify affected devices on a small number of customer environments performing a series of DNS host lookups for seemingly algorithmically generated domains (DGA). These domains feature the same TLDs as those seen in connections without prior DNS host lookups.  

Figure 3: Cyber AI Analyst data indicating a subset of DGAs queried via DNS by infected devices.

These DNS requests follow the activity reported by researchers, where infected devices query a hardcoded DNS server controlled by the threat actor for an DGA domain [2]. However, as the bulk of Darktrace’s investigations presented HTTP requests without a prior DNS host lookup, this activity indicates a significant deviation from the behavior reported by OSINT sources. This could indicate that multiple variations of the Socks5Systemz botnet were circulating at the time of investigation.

Most hostnames observed during this time of investigation follow a specific regular expression format: /[a-z]{7}\.(ua|net|info|com|ru)/ or /[a-z0-9]{15}\.(ua)/. Darktrace also noticed the HTTP GET requests for DGA domains followed a consistent URI pattern: /single.php?c=<STRING>. The requests were also commonly made using the “Mozilla/5.0 (Windows; U; MSIE 9.0; Windows NT 9.0; en-US)” user agent over port 80.

This URI pattern observed during Darktrace’s investigations appears to reflect infected devices contacting Socks5Systemz C2 servers to register the system and details of the host, and signal it is ready to receive further instructions [2]. These URIs are encrypted with a RC4 stream cipher and contain information relating to the device’s operating system and architecture, as well as details of the infection.

The HTTP GET requests during this time, which involved devices made to a variety a variety of similar DGA domains, appeared alongside IP addresses that were later identified as Socks5Systemz C2 servers.

Figure 4: Cyber AI Analyst investigation details highlighting HTTP GET activity whereby RC4 encrypted data is sent to proxy C2 domains.

However, not all affected devices observed by Darktrace used DGA domains to transmit RC4 encoded data. Some investigated systems were observed making similar HTTP GET requests over port 80, albeit to the external domain: “bddns[.]cc”, using the aforementioned Mozilla user agent. During these requests, Darktrace identified a consistent URI pattern, similar to that seen in the DGA domain GET requests: /sign/<RC4 cipher text>.  

Darktrace DETECT recognized the rarity of the domains and IPs that were connected to by affected devices, as well as the usage of the new Mozilla user agent.  The HTTP connections, and the corresponding Darktrace DETECT model breaches, parallel the analysis made by external researchers: if the initial DGA DNS requests do not return a valid C2 server, infected devices connect to, and request the IP address of a server from, the above-mentioned domain [2].

Connection to Proxy

After sending host and infection details via HTTP and receiving commands from the C2 server, affected devices were frequently observed initiating activity to join the Sock5Systemz botnet. Infected hosts would first make HTTP GET requests to an IP identified as Socks5Systemz’s proxy checker application, usually sending the URI “proxy-activity.txt” to the domain over the HTTP protocol. This likely represents an additional validation check to confirm that the infected device is ready to join the botnet.

Figure 5: Cyber AI Analyst investigation detailing HTTP GET requests over port 80 to the Socks5Systemz Proxy Checker Application.

Following the final validation checks, devices would then attempt TCP connections to a range of IPs, which have been associated with BackConnect proxy servers, over port 1074. At this point, the device is able to receive commands from actors who login to and operate the corresponding BackConnect server. This BackConnect server will transmit traffic from the user renting the segment of the botnet [2].

Darktrace observed a range of activity associated with this stage of the attack, including the use of new or unusual user agents, connections to suspicious IPs, and other anomalous external connectivity which represented a deviation from affected devices’ expected behavior.

Additional Activities Following Proxy Addition

The Darktrace Threat Research team found evidence of the possible deployment of additional malware strains during their investigation into devices affected by Socks5Systemz. IoCs associated with both the Amadey and PrivateLoader loader malware strains, both of which are known to distribute Socks5Systemz, were also observed on affected devices. Additionally, Darktrace observed multiple infected systems performing cryptocurrency mining operations around the time of the Sock5Systemz compromise, utilizing the MinerGate protocol to conduct login and job functions, as well as making DNS requests for mining pools.

While such behavior would fall outside of the expected activity for Socks5Systemz and cannot be definitively attributed to it, Darktrace did observe devices affected by the botnet performing additional malicious downloads and operations during its investigations.

結論

Ultimately, Darktrace’s anomaly-based approach to threat detection enabled it to effectively identify and alert for malicious Socks5Systemz botnet activity long before external researchers had documented its IoCs and tactics, techniques, and procedures (TTPs).  

In fact, Darktrace not only identified multiple distinct attack phases later outlined in external research but also uncovered deviations from these expected patterns of behavior. By proactively detecting emerging threats through anomaly detection rather than relying on existing threat intelligence, Darktrace is well positioned to detect evolving threats like Socks5Systemz, regardless of what their future iterations might look like.

Faced with the threat of persistent botnets, it is crucial for organizations to detect malicious activity in its early stages before additional devices are compromised, making it increasingly difficult to remediate. Darktrace’s suite of products enables the swift and effective detection of such threats. Moreover, when enabled in autonomous response mode, Darktrace RESPOND is uniquely positioned to take immediate, targeted actions to contain these attacks from the onset.

Credit to Adam Potter, Cyber Security Analyst, Anna Gilbertson, Cyber Security Analyst

付録

DETECT Model Breaches

  • Anomalous Connection / Multiple Failed Connections to Rare Endpoint
  • Anomalous Connection / Multiple Connections to New External TCP Port
  • Compromise / Beaconing Activity To External Rare
  • Compromise / DGA Beacon
  • Compromise / Beacon to Young Endpoint
  • Compromise / Slow Beaconing Activity To External Rare
  • Compromise / HTTP Beaconing to Rare Destination
  • Compromise / Quick and Regular Windows HTTP Beaconing
  • Compromise / Agent Beacon (Medium Period)
  • Compromise / Agent Beacon (Long Period)
  • Device / New User Agent
  • Device / New User Agent and New IP

Cyber AI Analyst Incidents

  • HTTP コマンド&コントロールの可能性
  • Possible HTTP Command and Control to Multiple Endpoints
  • Unusual Repeated Connections
  • Unusual Repeated Connections to Multiple Endpoints
  • Multiple DNS Requests for Algorithmically Generated Domains

侵害インジケータ

IoC - Type - Description

185.141.63[.]172 - IP Address - Socks5Systemz C2 Endpoint

193.242.211[.]141 - IP Address - Socks5Systemz C2 Endpoint

109.230.199[.]181 - IP Address - Socks5Systemz C2 Endpoint

109.236.88[.]134 - IP Address - Socks5Systemz C2 Endpoint

217.23.5[.]14 - IP Address - Socks5Systemz Proxy Checker App

88.80.148[.]8 - IP Address - Socks5Systemz Backconnect Endpoint

88.80.148[.]219 - IP Address - Socks5Systemz Backconnect Endpoint

185.141.63[.]4 - IP Address - Socks5Systemz Backconnect Endpoint

185.141.63[.]2 - IP Address - Socks5Systemz Backconnect Endpoint

195.154.188[.]211 - IP Address - Socks5Systemz Backconnect Endpoint

91.92.111[.]132 - IP Address - Socks5Systemz Backconnect Endpoint

91.121.30[.]185 - IP Address - Socks5Systemz Backconnect Endpoint

94.23.58[.]173 - IP Address - Socks5Systemz Backconnect Endpoint

37.187.148[.]204 - IP Address - Socks5Systemz Backconnect Endpoint

188.165.192[.]18 - IP Address - Socks5Systemz Backconnect Endpoint

/single.php?c=<RC4 data hex encoded> - URI - Socks5Systemz HTTP GET Request

/sign/<RC4 data hex encoded> - URI - Socks5Systemz HTTP GET Request

/proxy-activity.txt - URI - Socks5Systemz HTTP GET Request

datasheet[.]fun - Hostname - Socks5Systemz C2 Endpoint

bddns[.]cc - Hostname - Socks5Systemz C2 Endpoint

send-monitoring[.]bit - Hostname - Socks5Systemz C2 Endpoint

MITRE ATT&CK マッピング

コマンド&コントロール

T1071 - アプリケーションレイヤープロトコル

T1071.001 – Web protocols

T1568 – Dynamic Resolution

T1568.002 – Domain Generation Algorithms

T1132 – Data Encoding

T1132 – Non-Standard Encoding

T1090 – Proxy

T1090.002 – External Proxy

持ち出し

T1041 – Exfiltration over C2 channel

影響

T1496 – Resource Hijacking

参考文献

1. https://www.bleepingcomputer.com/news/security/socks5systemz-proxy-service-infects-10-000-systems-worldwide/

2. https://www.bitsight.com/blog/unveiling-socks5systemz-rise-new-proxy-service-privateloader-and-amadey

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著者について
Adam Potter
Cyber Analyst
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