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Living off the Land (環境に寄生する)手法:ハッカー達はあなたの環境にどうやって紛れ込むのか

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03
Nov 2021
03
Nov 2021
Cyber-criminals are increasingly ‘Living off the Land’, leveraging commonly-used tools to fly under the radar of conventional cyber defenses. Discover why Self-Learning AI is uniquely positioned to identify attacks leveraging this technique.

What is Living off the Land attack?

Living off the Land is a strategy which involves threat actors leveraging the utilities readily available within the target organization’s digital environment to move through the cyber kill chain. This is a popular method because It is often cheaper, easier, and more effective to make use of an organization’s own infrastructure in an attempt to attack rather than writing bespoke malware for every heist.

Living off the Land という言葉が最初に使われたのは2013年でしたが、こうしたツール、テクニック、および手順(TTP)は近年ブームとなっています。その理由の一つは、防御セキュリティのこれまでのアプローチ(例:以前の攻撃で遭遇したファイルハッシュ、ドメイン、およびその他の脅威の痕跡のブラックリスト化)がこれらの攻撃の識別に不十分であるからです。こうして、これらのステルス性の、しばしばファイルレスな攻撃はメインストリームに進出してきました。

How does Living off the Land attack work?

Living off the Land attacks have a particular history in highly organized, targeted hacking. APT groups have long favored Living off the Land TTPs, since evasion is a top priority. And trends show that ransomware groups are opting for human-operated ransomware that relies heavily on Living off the Land techniques, instead of commodity malware.

こうした不正な目的のために最もよく悪用されるツールとしては、Powershell、Windows Management Interface (WMI)、PsExecがあります。これらのツールはネットワーク管理者の日々のルーチン作業の一部として頻繁に使用されており、静的なルールやシグネチャに依存する従来のセキュリティツールは、多くの場合正当な使用と悪意ある使用を区別するのに苦労します。

Living off the Land 攻撃の特徴

Living off the Land攻撃において、脅威アクターが組織のインフラを使って攻撃を始めるには、彼らは標的のシステム上でコマンドを実行できなければなりません。つまり、Living off the Land攻撃とはネットワーク偵察、水平移動、永続化のための感染後のフレームワークであると言えます。

デバイスが一旦感染すれば、攻撃者は何百ものシステムツールを自由に使えます。これらはシステム上にプリインストールされているものもあれば、Microsoftの署名付きバイナリでダウンロードされるものもあります。そして、攻撃者の手によって、ネットワーク上の他の信頼されるサードパーティ製管理ツールも友から敵へと変貌します。

Living off the Land テクニックは進化するため、単一の典型的な 攻撃パターンを特定することは困難です。しかし、これらのTTPは大きくカテゴリ分けすることができます。

Microsoft署名付きLiving off the Land TTP

Microsoftはビジネスの世界で業界を超えて遍在しています。Living off the Land Binaries and Scripts (LOLBAS) プロジェクトでは、Living off the Land 攻撃においてAPTグループが使用する機能を含むすべてのMicrosoft署名付きバイナリおよびスクリプトを文書化することを目的としています。これまでに、それぞれ異なる不正目的に利用される恐れのある、135のシステムツールがこのリストに掲載されています。これらには新しいユーザーアカウントの作成、データ圧縮および抜き出し、システム情報の収集、ターゲットシステム上でのプロセスの起動、果てはセキュリティサービスの無効化までが含まれています。プリインストール済みの脆弱なツールについてのMicrosoftのドキュメンテーション、そしてLOLBASプロジェクトのリストはどちらも拡大中であり、すべてを網羅することはできないでしょう。

コマンドライン

ターゲットに悪意あるペイロードを届ける方法に関しては、最近の研究では WMI (WMIC.exe)、コマンドラインツール (cmd.exe)、そしてPowerShell (powershell.exe) が最もよく攻撃者に使われていることがわかっています。これらのよく悪用されるコマンドラインユーティリティは、セキュリティ設定やシステムプロパティの変更、ネットワークやデバイスステータスについての機密性情報の提供、そしてデバイス間でファイルの転送や実行を行わせるのに使用されています。

具体的には、これらコマンドライングループには3つの主要な特徴が共通しています:

  1. Windowsシステム上に既にある。
  2. ほとんどの管理者や社内プロセスによって日常のタスクに頻繁に使用されている。
  3. それぞれのコア機能を、ディスクにデータを書き込むことなく実行できる。

Mimikatz

Mimikatzはほとんどのシステムにプリインストールされていない点が他のツールとは異なります。これはパスワード、ハッシュ、PIN、Kerberosチケットのダンプに使われるオープンソースユーティリティです。一部のネットワーク管理者は脆弱性評価にMimikatzを使っているケースもありますが、Windowsシステムにプリインストールされているものではありません。

しかしMimikatz のダウンロード、インストール、使用を検知する従来型のセキュリティアプローチでは多くの場合不十分です。Mimikatzのようなツールを隠すための、検証済みの詳しく文書化されたさまざまなテクニックが存在しており、それほど高度でない攻撃者であっても文字列またはハッシュベースの検知を回避することは可能です。

Living off the Land攻撃と戦う自己学習型AI

Living off the Land テクニックは犯罪者を組織のデジタル環境に溶け込ませるのにきわめて効果的であることが実証されています。1つのデジタルエコシステムのログには、日々何百万もの認証、ネットワークツール、プロセスが記録されることも珍しくありません。この膨大なデジタルノイズの中から正当なツールの悪意ある利用をどうやって特定することができるでしょうか?

ほとんどの脅威同様、基本的なネットワーク衛生管理は最初のステップです。これには最小権限の原則の適用、必要のないすべてのプログラムを無効化する、ソフトウェアホワイトリストを設定する、アセットおよびアプリケーションの在庫管理を実施する、などが含まれます。しかし、これらの対策は正しい方向に向けた第一歩ではあるものの、高度な攻撃者なら十分な時間があれば必ずこれらをすり抜けることができるでしょう。

自己学習型AI技術は、組織内のインフラを悪用する攻撃者に光を当てるための基礎となっています。AIは、あらゆるデバイスやユーザーの「生活パターン」を理解し、組織固有のデジタル環境をゼロから学習します。そのため、Living off the Land攻撃は、一連の微妙な逸脱からリアルタイムで特定されます。例えば、新しいクレデンシャルやSMB/DCE-RPCの異常な使用などが挙げられます。

それぞれのビジネスに対する深い理解により、他のツールのレーダーには引っかからない攻撃も特定することができます。Living off the Land攻撃に対し、AIは特定のツールの利用がその組織にとって正常であることを認識しつつも、そのツールの使われ方によっては一見無害な動作も間違いなく悪性であることを識別できるのです。

たとえば、自己学習型AIが Powershell ユーザーエージェントの頻繁な使用を複数のデバイスで観測したとしても、そのユーザーエージェントが普段と異なる時間に観測されたときにのみインシデントを報告します。

同様に、Darktraceは、毎日何千ものデバイスの組み合わせの間で送信されるWMIコマンドを観察するかもしれませんが、コマンドの送信元と送信先の双方にとって珍しい場合にのみ、そのような活動に対して警告を発します。

そしてMimikatz悪用のかすかな兆候、たとえば新しい認証情報の使用や珍しいSMBトラフィックなども、インフラ内の通常のオペレーションに埋もれてしまうことはありません。

Living off the Landテクニックは当分なくならないでしょう。これを踏まえて、多くのセキュリティチームは過去の攻撃データに頼って次の攻撃を発見しようとするレガシーベースの防御から脱却し、周囲環境についての個別の、また変化する理解をもとに脅威の兆候であるかすかな逸脱を、その脅威が正当なツールを使ったものであっても検知する、AIに移行しつつあります。

この脅威事例についての考察およびMITRE ATT&CKマッピングにはDarktraceアナリストIsabel Finn とPaul Jennings が協力しました。

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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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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.

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Looking Beyond Secure Email Gateways with the Latest Innovations to Darktrace/Email

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09
Apr 2024

Organizations Should Demand More from their Email Security

In response to a more intricate threat landscape, organizations should view email security as a critical component of their defense-in-depth strategy, rather than defending the inbox alone with a traditional Secure Email Gateway (SEG). Organizations need more than a traditional gateway – that doubles, instead of replaces, the capabilities provided by native security vendor – and require an equally granular degree of analysis across all messaging, including inbound, outbound, and lateral mail, plus Teams messages.  

Darktrace/Email is the industry’s most advanced cloud email security, powered by Self-Learning AI. It combines AI techniques to exceed the accuracy and efficiency of leading security solutions, and is the only security built to elevate, not duplicate, native email security.  

With its largest update ever, Darktrace/Email introduces the following innovations, finally allowing security teams to look beyond secure email gateways with autonomous AI:

  • AI-augmented data loss prevention to stop the entire spectrum of outbound mail threats
  • an easy way to deploy DMARC quickly with AI
  • major enhancements to streamline SOC workflows and increase the detection of sophisticated phishing links
  • expansion of Darktrace’s leading AI prevention to lateral mail, account compromise and Microsoft Teams

What’s New with Darktrace/Email  

Data Loss Prevention  

Block the entire spectrum of outbound mail threats with advanced data loss prevention that builds on tags in native email to stop unknown, accidental, and malicious data loss

Darktrace understands normal at individual user, group and organization level with a proven AI that detects abnormal user behavior and dynamic content changes. Using this understanding, Darktrace/Email actions outbound emails to stop unknown, accidental and malicious data loss.  

Traditional DLP solutions only take into account classified data, which relies on the manual input of labelling each data piece, or creating rules to catch pattern matches that try to stop data of certain types leaving the organization. But in today’s world of constantly changing data, regular expression and fingerprinting detection are no longer enough.

  • Human error – Because it understands normal for every user, Darktrace/Email can recognize cases of misdirected emails. Even if the data is correctly labelled or insensitive, Darktrace recognizes when the context in which it is being sent could be a case of data loss and warns the user.  
  • Unclassified data – Whereas traditional DLP solutions can only take action on classified data, Darktrace analyzes the range of data that is either pending labels or can’t be labeled with typical capabilities due to its understanding of the content and context of every email.  
  • Insider threat – If a malicious actor has compromised an account, data exfiltration may still be attempted on encrypted, intellectual property, or other forms of unlabelled data to avoid detection. Darktrace analyses user behaviour to catch cases of unusual data exfiltration from individual accounts.

And classification efforts already in place aren’t wasted – Darktrace/Email extends Microsoft Purview policies and sensitivity labels to avoid duplicate workflows for the security team, combining the best of both approaches to ensure organizations maintain control and visibility over their data.

End User and Security Workflows

Achieve more than 60% improvement in the quality of end-user phishing reports and detection of sophisticated malicious weblinks1

Darktrace/Email improves end-user reporting from the ground up to save security team resource. Employees will always be on the front line of email security – while other solutions assume that end-user reporting is automatically of poor quality, Darktrace prioritizes improving users’ security awareness to increase the quality of end-user reporting from day one.  

Users are empowered to assess and report suspicious activity with contextual banners and Cyber AI Analyst generated narratives for potentially suspicious emails, resulting in 60% fewer benign emails reported.  

Out of the higher-quality emails that end up being reported, the next step is to reduce the amount of emails that reach the SOC. Darktrace/Email’s Mailbox Security Assistant automates their triage with secondary analysis combining additional behavioral signals – using x20 more metrics than previously – with advanced link analysis to detect 70% more sophisticated malicious phishing links.2 This directly alleviates the burden of manual triage for security analysts.

For the emails that are received by the SOC, Darktrace/Email uses automation to reduce time spent investigating per incident. With live inbox view, security teams gain access to a centralized platform that combines intuitive search capabilities, Cyber AI Analyst reports, and mobile application access. Analysts can take remediation actions from within Darktrace/Email, eliminating console hopping and accelerating incident response.

Darktrace takes a user-focused and business-centric approach to email security, in contrast to the attack-centric rules and signatures approach of secure email gateways

Microsoft Teams

Detect threats within your Teams environment such as account compromise, phishing, malware and data loss

Around 83% of Fortune 500 companies rely on Microsoft Office products and services, particularly Teams and SharePoint.3

Darktrace now leverages the same behavioral AI techniques for Microsoft customers across 365 and Teams, allowing organizations to detect threats and signals of account compromise within their Teams environment including social engineering, malware and data loss.  

The primary use case for Microsoft Teams protection is as a potential entry vector. While messaging has traditionally been internal only, as organizations open up it is becoming an entry vector which needs to be treated with the same level of caution as email. That’s why we’re bringing our proven AI approach to Microsoft Teams, that understands the user behind the message.  

Anomalous messaging behavior is also a highly relevant indicator of whether a user has been compromised. Unlike other solutions that analyze Microsoft Teams content which focus on payloads, Darktrace goes beyond basic link and sandbox analysis and looks at actual user behavior from both a content and context perspective. This linguistic understanding isn’t bound by the requirement to match a signature to a malicious payload, rather it looks at the context in which the message has been delivered. From this analysis, Darktrace can spot the early symptoms of account compromise such as early-stage social engineering before a payload is delivered.

Lateral Mail Analysis

Detect and respond to internal mailflow with multi-layered AI to prevent account takeover, lateral phishing and data leaks

The industry’s most robust account takeover protection now prevents lateral mail account compromise. Darktrace has always looked at internal mail to inform inbound and outbound decisions, but will now elevate suspicious lateral mail behaviour using the same AI techniques for inbound, outbound and Teams analysis.

Darktrace integrates signals from across the entire mailflow and communication patterns to determine symptoms of account compromise, now including lateral mailflow

Unlike other solutions which only analyze payloads, Darktrace analyzes a whole range of signals to catch lateral movement before a payload is delivered. Contributing yet another layer to the AI behavioral profile for each user, security teams can now use signals from lateral mail to spot the early symptoms of account takeover and take autonomous actions to prevent further compromise.

DMARC

Gain in-depth visibility and control of 3rd parties using your domain with an industry-first AI-assisted DMARC

Darktrace has created the easiest path to brand protection and compliance with the new Darktrace/DMARC. This new capability continuously stops spoofing and phishing from the enterprise domain, while automatically enhancing email security and reducing the attack surface.

Darktrace/DMARC helps to upskill businesses by providing step by step guidance and automated record suggestions provide a clear, efficient road to enforcement. It allows organizations to quickly achieve compliance with requirements from Google, Yahoo, and others, to ensure that their emails are reaching mailboxes.  

Meanwhile, Darktrace/DMARC helps to reduce the overall attack surface by providing visibility over shadow-IT and third-party vendors sending on behalf of an organization’s brand, while informing recipients when emails from their domains are sent from un-authenticated DMARC source.

Darktrace/DMARC integrates with the wider Darktrace product platform, sharing insights to help further secure your business across Email Attack Path and Attack Surface management.

結論

To learn more about the new innovations to Darktrace/Email download the solution brief here.

All of the new updates to Darktrace/Email sit within the new Darktrace ActiveAI Security Platform, creating a feedback loop between email security and the rest of the digital estate for better protection. Click to read more about the Darktrace ActiveAI Security Platform or to hear about the latest innovations to Darktrace/OT, the most comprehensive prevention, detection, and response solution purpose built for critical infrastructures.  

Learn about the intersection of cyber and AI by downloading the State of AI Cyber Security 2024 report to discover global findings that may surprise you, insights from security leaders, and recommendations for addressing today’s top challenges that you may face, too.

参考文献

[1] Internal Darktrace Research

[2] Internal Darktrace Research

[3] Essential Microsoft Office Statistics in 2024

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Carlos Gray
Product Manager

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Managing Risk Beyond CVE Scores With the Latest Innovations to Darktrace/OT

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09
Apr 2024

Identifying Cyber Risk in Industrial Organizations

Compromised OT devices in ICS and SCADA environments pose significant physical risks, even endangering lives. However, identifying CVEs in the multitude of complex OT devices is labor-intensive and time-consuming, draining valuable resources.

Even after identifying a vulnerability, implementing a patch presents its own challenges limited maintenance windows and the need for uninterrupted operations strain IT and OT teams often leading organizations to prioritize availability over security leading vulnerabilities remaining unresolved for over 5 years on average. (1)

Darktrace’s New Innovation

Darktrace is an industry leader in cybersecurity with 10+ years of experience securing OT environments where we take a fundamentally different approach using Self-Learning AI to enhance threat detection and response.

Continuing to combat the expanding threat landscape, Darktrace is excited to announce new capabilities that enable a contextualized and proactive approach to managing cyber risk at industrial organizations.

Today we launch an innovation to our OT Cybersecurity solution, Darktrace/OT, that will add a layer of proactivity, enabling a comprehensive approach to risk management. This industry leading innovation for Darktrace/OT moves beyond CVE scores to redefine vulnerability management for critical infrastructure, tackling the full breadth of risks not limited by traditional controls.  

Darktrace/OT is the only OT security solution with comprehensive Risk Management which includes:

  • Contextualized risk analysis unique to your organization
  • The most realistic evaluation and prioritization of OT risk
  • Effectively mitigate risk across your OT infrastructure, with and without patching.
  • The only OT security solution that evaluates your defenses against Advanced Persistent Threat (APT) Groups.

The most comprehensive prevention, detection, and response solution purpose built for Critical Infrastructures

Darktrace’s Self-Learning AI technology is a cutting-edge innovation that implements real time prevention, detection, response, and recovery for operational technologies and enables a fundamental shift from the traditional approach to cyber defense by learning a ‘pattern of life’ for every network, device, and user.  

Rather than relying on knowledge of past attacks, AI technology learns what is ‘normal’ for its environment, discovering previously unknown threats by detecting subtle shifts in behavior. Through identifying these unexpected anomalies, security teams can investigate novel attacks, discover blind spots, have live time visibility across all their physical and digital assets, and reduce time to detect, respond to, and triage security events.  

  • Achieve greater visibility of OT and IT devices across all levels of the Purdue Model.
  • The industry's only OT security to scale threat detection and response, with a 92% time saving from triage to recovery.  
  • The only OT focused security solution to provide bespoke Risk Management.

To learn more about how Darktrace/OT approaches unique use cases for industrial organizations visit the Darktrace/OT Webpage or join us LIVE at a city near you.

Read more below to discover how new innovations to Darktrace/OT are bringing a new, contextualized approach to Risk Management for Industrial organizations.

For more information on the entire Darktrace/OT Solution read our solution brief here.

Darktrace/OT and New Risk Management

Risk Identification

Leveraging the visibility of Darktrace/OT which identifies individual systems throughout the Purdue Model and the relationship between them, Darktrace/OT identifies high-risk CVEs and presents potential attack routes that go beyond techniques requiring a known exploit, such as misuse of legitimate services. Each attack path will have a mathematical evaluation of difficulty and impact from initial access to the high value objectives.  

Together this gives comprehensive coverage over your real and potential risks from both an attacker and known vulnerability perspectives. OT attack paths as seen here even leverage insights between the industrial and corporate communications to reveal ways threat actors may take advantage of IT-OT convergence. This revelation of imperceptible risks fills gaps in traditional risk analysis like remote access and insider threats.

Figure 1: Darktrace/OT visualizing the most critical attack paths at an organization
Figure 1: Darktrace/OT visualizing the most critical attack paths at an organization
Figure 2: A specific Attack Path identified by Darktrace/OT

Risk Prioritization

Darktrace/OT prioritizes remediations and mitigations based on difficulty and damage to your unique organization, using the established Attack Paths.

We ascertain the priorities that apply to your organization beyond pure theoretical damage answering questions like:

  • How difficult is a particular vulnerability to exploit considering the steps an attacker would require to reach it?
  • And, how significant would the impact be if it was exploited within this particular network?

This expanded approach to risk prioritization has a much more comprehensive evaluation of your organization's unique risk than has ever been possible before. Traditional approaches of ranking only known vulnerabilities with isolated scores using CVSS and exploitability metrics, often leaves gaps in IT-OT risks and is blind to legitimate service exploitation.

Figure 3: Darktrace/OT leverages its contextual understand of the organization’s network to prioritize remediation that will have the positive impact on the risk score

Darktrace provides mitigation strategies associated with each identified risk and the relevant impact it has on your overall risk posture, across all MITRE ATT&CK techniques.

What sets Darktrace apart is our ability to contextualize these mitigations within the broader business. When patching vulnerabilities directly isn’t possible, Darktrace identifies alternative actions that harden attack paths leading to critical assets. Hardening the surrounding attack path increases the difficulty and therefore reduces the likelihood and impact of a breach.

That means unpatched vulnerabilities and vulnerable devices aren’t left unprotected. This also has an added bonus, those hardening techniques work for all devices in that network segment, so apply one change, secure many.

Figure 4: Darktrace prioritizes mitigation reducing accessibility of vulnerability and the overall risk score when patches aren’t available

Communicate Board Level Risk with APT Threat Mapping

Darktrace/OT bridges theory and practice as the only security solution that maps MITRE techniques, frequently used by APT Groups, onto AI-assessed critical Attack Paths. This unique solution provides unparalleled insights including sector and location intelligence, possible operating platforms, common techniques, exploited CVEs, and the number of potential devices affected in your environment, supporting holistic risk assessment and proactive defense measures.

Ultimately, this becomes a power dashboard to communicate board level risk, using both metric based evidence and industry standard threat mapping.

結論

Darktrace/OT is part of the Darktrace ActiveAI Security Platform a native, holistic, AI-driven platform built on over ten years of AI research. It helps security teams shift to more a productive mode, finding the known and the unknown attacks and transforming the SOC with the various Darktrace products to drive efficiency gains. It does this across the whole incident lifecycle to lower risk, reduce time spent on active incidents, and drive return on investment.

Discover more about Darktrace's ever-strengthening platform with the upcoming changes coming to our Darktrace/Email product and other launch day blogs.

Join Darktrace LIVE half-day event to understand the reality versus the hype surrounding AI and how to achieve cyber resilience.

Learn about the intersection of cyber and AI by downloading the State of AI Cyber Security 2024 report to discover global findings that may surprise you, insights from security leaders, and recommendations for addressing today’s top challenges that you may face, too.  

参考文献

1. https://research-information.bris.ac.uk/ws/portalfiles/portal/313646831/Catch_Me_if_You_Can.pdf

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Mitchell Bezzina
VP, Product and Solutions Marketing
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