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Falsches schreiben: Warum das Link-Rewriting von Mimecast ein falsches Gefühl von Sicherheit vermittelt

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04
November 2020
04
November 2020
Traditional email gateways rely on pre-emptively rewriting links so that down the line, when they have updated information about a potential attack, they can take action. This blog exposes the pitfalls of this approach and examines a more modern approach to email security.

Many organizations feel secure in the knowledge that their email gateway is rewriting all of the harmful links targeting their employees. Link rewriting is a common technique that involves encoding URLs sent via email into a link that redirects the user to the gateway’s own servers. These servers contain some unique codes that then track the user and perform later checks to determine whether the link is malicious.

This blog reveals why the sense of protection this gives is a fallacy, and how rewriting links does not equate to protecting the end user from actual harm. In fact, gateways’ reliance on this technique is actually an indicator of one of their fundamental flaws: their reliance on rules and signatures of previously recognized threats, and their consequent inability to stop threats on the first encounter. The reason these tools pre-emptively rewrite links is so they can make a determination later on: with the link now pointing to their own servers, they can leverage their updated assessment of that link and block a malicious site, once more information has become available (often once ‘patient zero’ has become infected; and the damage is already done).

Email security that recognizes and blocks threats on the first encounter has no need to rewrite every link.

How to measure success

If the sheer number of links rewritten is to be our measure of success, then traditional gateways win every time. For instance, Mimecast will usually rewrite 100% of the harmful links that Antigena Email locks. In fact, it rewrites nearly 100% of all links. That even includes links pointing to trusted websites like LinkedIn and Twitter, and even emails containing links to the recipient’s own website. So when tim.cook[at]apple.com receives a link to apple.com, for example, ‘mimecast.com’ will still dominate the URL.

Some organizations suffering from low first-encounter catch rates with their gateways have responded by increasing employee education: training the human to spot the giveaways of a phishing email. With email attacks getting more targeted and sophisticated, humans should never be considered the last line of defense, and rewriting links makes the situation even worse. If you’re training your users to watch which links they’re clicking, and every one of those links reads ‘mimecast.com’, how are your users supposed to learn what’s good, bad, or sketchy when every URL looks the same?

Moreover, when Mimecast’s URL gateway is down, these rewritten links don’t work (and the same applies to protected attachments). This results in business downtime which is intolerable for businesses in these critical and challenging times.

We can see the effect of blanket rewriting through Darktrace’s user interface, which shows us the frequency of rewritten links over time. Looking back over three days, this particular customer – who was trialing Antigena Email alongside Mimecast, received 155,008 emails containing rewritten links. Of those, 1,478 were anomalous, and Darktrace’s AI acted to immediately lock those links, protecting even the first recipient from harm. The remaining 153,530 links were all unnecessarily rewritten.

Figure 1: Over 155,000 inbound emails contained rewritten Mimecast links

If it comes to actually stopping the threat when a user goes to click that rewritten link, gateway tools fail. Their reliance on legacy checks like reputation, deny-lists, and rules and signatures mean that malicious content will sometimes sit for days or weeks without any meaningful action, as the technology requires at least one – and usually many – ‘patient zeros’ before determining a URL or an attachment as malicious, and updating their deny-lists.

Let’s look at the case of an attack launched from entirely new infrastructure: from a freshly purchased domain, and containing a newly created malicious payload. None of the typical metrics legacy tools search for appear as malicious, and so of course, the threat gets through, and ‘patient zero’ is infected.

Figure 2: ‘Patient Zero’ denotes the first victim of an email attack.

It inevitably takes time for the malicious link to be recognized as malicious, and for that to be reported. By this point, large swathes of the workforce have also become infected. We can call this the ‘time to detection’.

Figure 3: The time to detection

As legacy tools then update their lists in recognition of the attack, the malware continues to infect the organization, with more users engaging in the contents of the email.

Figure 4: The legacy tool reacts

Finally, the legacy tool reacts, updating its deny-list and providing substantive action to protect the end user from harm. By this point, hundreds of users across multiple organizations may have interacted with the links in some way.

Figure 5: Many ‘patient zeros’ are required before the threat is deny-listed

Email gateways’ reliance on rewriting links is directly related to their legacy approach to detection. They do it so that later down the line, when they have updated information about a potential attack, they can take action. Until then, it’s just a rewritten link, and if clicked on, it will bring the user to whatever website was hiding underneath it.

These links are also rewritten in an attempt to grasp an understanding of what user network behavior looks like. But far from giving an accurate or in-depth picture of network activity, this method barely scratches the surface of the wider behaviors of users across the organization.

Alongside Darktrace’s Enterprise Immune System, Antigena Email can pull these insights directly from a unified, central AI engine that has complete and direct visibility over an organization’s entire digital estate – not just links accessed from emails, but network activity as a whole – and not a makeshift version where it is assumed people only visit links through emails. It also pulls insights from user behavior in the cloud and across SaaS applications – from Salesforce to Microsoft Teams.

Taking real action in real time

While gateways rewrite everything in order to leave the door open to make assessments later on, Darktrace is able to take action when it needs to – before the email poses a threat in the inbox. The technology is uniquely able to do this due to its high success rates for malicious emails seen on first encounter. And it’s able to achieve such high success rates because it takes a much more sophisticated approach to detection that uses AI to catch a threat – regardless of whether or not that threat has been seen before.

Darktrace’s understanding of ‘normal’ for the human behind email communications allows it to not only detect subtle deviations that are indicative of a cyber-threat, but respond to that threat at the point of delivery. This response is targeted, proportionate and non-disruptive, and varies according to the nature of the attack. While Darktrace’s unsupervised machine learning can accurately identify deviations from ‘normal’, its supervised machine learning models are able to classify the intention behind the email; what the attacker is trying to do (extort information, solicit a payment, harvest credentials, or convince the user to download a malicious attachment).

Crucially, organizations trialing both approaches to security find that Antigena Email consistently identifies threats that Mimecast and other tools miss. With the scale and sophistication of email attacks growing, the need for a proactive and modern approach to email security is paramount. Organizations need to ensure they are measuring their sense of protection with the right yardstick, and adopt a technology that can take meaningful action before damage is done.

Trial Antigena Email today

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Darktrace Cyber-Analysten sind erstklassige Experten für Threat Intelligence, Threat Hunting und Incident Response. Sie bieten Tausenden von Darktrace Kunden auf der ganzen Welt rund um die Uhr SOC-Support. Einblicke in das SOC-Team wird ausschließlich von diesen Experten verfasst und bietet Analysen von Cyber-Vorfällen und Bedrohungstrends, die auf praktischen Erfahrungen in diesem Bereich basieren.
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Dan Fein
VP, Produkt

Based in New York, Dan joined Darktrace’s technical team in 2015, helping customers quickly achieve a complete and granular understanding of Darktrace’s product suite. Dan has a particular focus on Darktrace/Email, ensuring that it is effectively deployed in complex digital environments, and works closely with the development, marketing, sales, and technical teams. Dan holds a Bachelor’s degree in Computer Science from New York University.

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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.

Schlussfolgerung

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.

References

[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.

Schlussfolgerung

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.  

References

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

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About the author
Mitchell Bezzina
VP, Product and Solutions Marketing
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