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April 22, 2021

Darktrace Identifies APT35 in Pre-Infected State

Learn how Darktrace identified APT35 (Charming Kitten) in a pre-infected environment. Gain insights into the detection and mitigation of this threat.
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.
Written by
Max Heinemeyer
Global Field CISO
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22
Apr 2021

What is APT35?

APT35, sometimes referred to as Charming Kitten, Imperial Kitten, or Tortoiseshell, is a notorious cyber-espionage group which has been active for nearly 10 years. Famous for stealing scripts from HBO’s Game of Thrones in 2017 and suspected of interfering in the U.S. presidential election last year, it has launched extensive campaigns against organizations and officials across North America and the Middle East. Public attribution has associated APT35 with an Iran-based nation state threat actor.

Darktrace regularly detects attacks by many known threat actors including Evil Corp and APT41, alongside large amounts of malicious but uncategorized activity from sophisticated attack groups. As Cyber AI doesn’t rely on pre-defined rules, signatures, or threat intelligence to detect cyber-attacks, it often detects new and previously unknown threats.

This blog post examines a real-world instance of APT35 activity in an organization in the EMEA region. Darktrace observed this activity last June, but due to ongoing investigations, details are only now being released with the wider community. It represents an interesting case for the value of self-learning AI in two key ways:

  • Identifying ‘low and slow’ attacks: How do you spot an attacker that is lying low and conducts very little detectable activity?
  • Detecting pre-existing infections without signatures: What if a threat actor is already inside the system when Cyber AI is activated?

Advanced Persistent Threats (APTs) lying low

APT35 had already infected a single corporate device, likely via a spear phishing email, when Cyber AI was deployed in the company’s digital estate for the first time.

The infected device exhibited no other signs of malicious activity beyond continued command and control (C2) beaconing, awaiting instructions from the attackers for several days. This is what we call ‘lying low’ – where the hacker stays present within a system, but remains under the radar, avoiding detection either intentionally, or because they’re focusing on another victim while being content with backdoor access into the organization.

Either way, this is a nightmare scenario for a security team and any security vendor: an APT which has established a foothold and is lying in wait to continue their attack – undetected.

Finding the infected device

When Darktrace’s AI was first activated, it spent five business days learning the unique ‘patterns of life’ for the organization. After this initial, short learning period, Darktrace immediately flagged the infected device and the C2 activity.

Although the breach device had been beaconing since before Darktrace was implemented, Cyber AI automatically clusters devices into ‘peer groups’ based on similar behavioral patterns, enabling Darktrace to identify the continued C2 traffic coming from the device as highly unusual in comparison to the wider, automatically identified peer group. None of its behaviorally close neighbors were doing anything remotely similar, and Darktrace was therefore able to determine that the activity was malicious, and that it represented C2 beaconing.

Darktrace detected the APT35 C2 activity without the use of any signatures or threat intelligence on multiple levels. Responding to the alerts, the internal security team quickly isolated the device and verified with the Darktrace system that no further reconnaissance, lateral movement, or data exfiltration had taken place.

APT35 ‘Charming Kitten’ analysis

Once the C2 was detected, Cyber AI Analyst immediately began analyzing the infected device. The Cyber AI Analyst only highlights the most severe incidents in any given environment and automates many of the typical level one and level two SOC tasks. This includes reviewing all alerts, investigating the scope and nature of each event, and reducing time to triage by 92%.

Figure 1: Similar Cyber AI Analyst report observing C2 communications

Numerous factors made the C2 activity stand out strongly to Darktrace. Combining all those small anomalies, Darktrace was able to autonomously prioritize this behavior and classify it as the most significant security incident in the week.

Figure 2: Example list of C2 detections for an APT35 attack

Some of the command and control destinations were known to threat intelligence and open-source intelligence (OSINT) – for instance, the domain cortanaservice[.]com is a known C2 domain for APT35.

However, the presence of a known malicious domain does not guarantee detection. In fact, the organization had a very mature security stack, yet they failed to discover the existing APT35 infection until Darktrace was activated in their environment.

Assessing the impact of the intrusion

Once an intrusion has been identified, it is important to understand the extent of it – such as whether lateral movement is occurring and what connectivity the infected device has in general. Asset management is never perfect, so it can be very hard for organizations to determine what damage a compromised device is capable of inflicting.

Darktrace presents this information in real time, and from a bird’s-eye perspective, making the assessment very simple. It immediately highlights which subnet the device is located in and any further context.

Figure 3: Darktrace’s Threat Visualizer displaying the connectivity of a device

Based on this information, the organization confirmed that it was a corporate device that had been infected by APT35. As Darktrace shows any credentials associated with the device, a quick assessment could be made of potentially compromised accounts.

Figure 4: Similar and associated credentials of a device

Luckily, only a single local user account was associated with the device.

The exact level of privileges and connectivity which the infected device had, as well as the extent to which the intrusion might have spread from the initially infected device, was still uncertain. By looking at the device’s event log, this became rapidly clear within minutes.

Filtering first for internal connections only (excluding any connections going to the Internet) gave a good idea of the level of connectivity of the device. A cursory glance showed that the device did indeed have some level of internal connectivity. It made DNS requests to the internal domain controller and was making successful NetBIOS connections over ports 135 and 139 internally.

By filtering further in the event log, it quickly became clear that in this time the device had not used any administrative channels, such as RDP, SSH, Telnet, or SMB. This is a strong indicator that no lateral movement over common channels had taken place.

It is more difficult to assess whether the device was performing any other suspicious activity, like stealthy reconnaissance or staging data from other internal devices. Darktrace provided another capability to assess this quickly – filtering the device’s network connections to show only unusual or new connections.

Figure 5: Event device log filtered to show unusual connections only

Darktrace assesses each individual connection for every entity observed in context, using its unsupervised machine learning to evaluate how unusual a given connection is. This could be a single new failed internal connection attempt, indicating stealthy reconnaissance, or a connection over SMB at an unusual time to a new internal destination, implying lateral movement or data staging.

By filtering for only unusual or new connections, Darktrace’s AI produces further leads that can be pursued extremely quickly, thanks to the context and added visibility.

No further suspicious internal connections were observed, strengthening the hypothesis that APT35 was lying low at that time.

Unprecedented but not unpreventable

Darktrace’s 24/7 monitoring service, Proactive Threat Notifications, would have alerted on and escalated the incident. Darktrace RESPOND would have responded autonomously and enforced normal activity for the device, preventing the C2 traffic without interrupting regular business workflows.

It is impossible to predefine where the next attack will come from. APT35 is just one of the many sophisticated threat actors on the scene, and with such a diverse and volatile threat landscape, unsupervised machine learning is crucial in spotting and defending against anomalies, no matter what form they take.

This case study helps illustrate how Darktrace detects pre-existing infections and ‘low and slow’ attacks, and further shows how Darktrace can be used to quickly understand the scope and extent of an intrusion.

Learn how Cyber AI Analyst detected APT41 two weeks before public attribution

Shortened list of C2 detections over four days on the infected device:

  • Compromise / Sustained TCP Beaconing Activity To Rare Endpoint
  • Compromise / Beaconing Meta Model
  • Compromise / Beaconing Activity To External Rare
  • Compromise / SSL Beaconing To Rare Destination
  • Compromise / Slow Beaconing To External Rare
  • Compromise / High Volume of Connections with Beacon Score
  • Compromise / Unusual Connections to Rare Lets Encrypt
  • Compromise / Beacon for 4 Days
  • Compromise / Agent Beacon

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.
Written by
Max Heinemeyer
Global Field CISO

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September 23, 2025

It’s Time to Rethink Cloud Investigations

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Cloud Breaches Are Surging

Cloud adoption has revolutionized how businesses operate, offering speed, scalability, and flexibility. But for security teams, this transformation has introduced a new set of challenges, especially when it comes to incident response (IR) and forensic investigations.

Cloud-related breaches are skyrocketing – 82% of breaches now involve cloud-stored data (IBM Cost of a Data Breach, 2023). Yet incidents often go unnoticed for days: according to a 2025 report by Cybersecurity Insiders, of the 65% of organizations experienced a cloud-related incident in the past year, only 9% detected it within the first hour, and 62% took more than 24 hours to remediate it (Cybersecurity Insiders, Cloud Security Report 2025).

Despite the shift to cloud, many investigation practices remain rooted in legacy on-prem approaches. According to a recent report, 65% of organizations spend approximately 3-5 days longer when investigating an incident in the cloud vs. on premises.

Cloud investigations must evolve, or risk falling behind attackers who are already exploiting the cloud’s speed and complexity.

4 Reasons Cloud Investigations Are Broken

The cloud’s dynamic nature – with its ephemeral workloads and distributed architecture – has outpaced traditional incident response methods. What worked in static, on-prem environments simply doesn’t translate.

Here’s why:

  1. Ephemeral workloads
    Containers and serverless functions can spin up and vanish in minutes. Attackers know this as well – they’re exploiting short-lived assets for “hit-and-run” attacks, leaving almost no forensic footprint. If you’re relying on scheduled scans or manual evidence collection, you’re already too late.
  2. Fragmented tooling
    Each cloud provider has its own logs, APIs, and investigation workflows. In addition, not all logs are enabled by default, cloud providers typically limit the scope of their logs (both in terms of what data they collect and how long they retain it), and some logs are only available through undocumented APIs. This creates siloed views of attacker activity, making it difficult to piece together a coherent timeline. Now layer in SaaS apps, Kubernetes clusters, and shadow IT — suddenly you’re stitching together 20+ tools just to find out what happened. Analysts call it the ‘swivel-chair Olympics,’ and it’s burning hours they don’t have.
  3. SOC overload
    Analysts spend the bulk of their time manually gathering evidence and correlating logs rather than responding to threats. This slows down investigations and increases burnout. SOC teams are drowning in noise; they receive thousands of alerts a day, the majority of which never get touched. False positives eat hundreds of hours a month, and consequently burnout is rife.  
  4. Cost of delay
    The longer an investigation takes, the higher its cost. Breaches contained in under 200 days save an average of over $1M compared to those that linger (IBM Cost of a Data Breach 2025).

These challenges create a dangerous gap for threat actors to exploit. By the time evidence is collected, attackers may have already accessed or exfiltrated data, or entrenched themselves deeper into your environment.

What’s Needed: A New Approach to Cloud Investigations

It’s time to ditch the manual, reactive grind and embrace investigations that are automated, proactive, and built for the world you actually defend. Here’s what the next generation of cloud forensics must deliver:

  • Automated evidence acquisition
    Capture forensic-level data the moment a threat is detected and before assets disappear.
  • Unified multi-cloud visibility
    Stitch together logs, timelines, and context across AWS, Azure, GCP, and hybrid environments into a single unified view of the investigation.
  • Accelerated investigation workflows
    Reduce time-to-insight from hours or days to minutes with automated analysis of forensic data, enabling faster containment and recovery.
  • Empowered SOC teams
    Fully contextualised data and collaboration workflows between teams in the SOC ensure seamless handover, freeing up analysts from manual collection tasks so they can focus on what matters: analysis and response.

Attackers are already leveraging the cloud’s agility. Defenders must do the same — adopting solutions that match the speed and scale of modern infrastructure.

Cloud Changed Everything. It’s Time to Change Investigations.  

The cloud fundamentally reshaped how businesses operate. It’s time for security teams to rethink how they investigate threats.

Forensics can no longer be slow, manual, and reactive. It must be instant, automated, and cloud-first — designed to meet the demands of ephemeral infrastructure and multi-cloud complexity.

The future of incident response isn’t just faster. It’s smarter, more scalable, and built for the environments we defend today, not those of ten years ago.  

On October 9th, Darktrace is revealing the next big thing in cloud security. Don’t miss it – sign up for the webinar.

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Kellie Regan
Director, Product Marketing - Cloud Security

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September 22, 2025

Understanding the Canadian Critical Cyber Systems Protection Act

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Introduction: The Canadian Critical Cyber Systems Protection Act

On 18 June 2025, the Canadian federal Government introduced Bill C-8 which, if adopted following completion of the legislative process, will enact the Critical Cyber Systems Protection Act (CCSPA) and give Canada its first federal, cross-sector and legally binding cybersecurity regime for designated critical infrastructure providers. As of August 2025, the Bill has completed first reading and stands at second reading in the Canadian House of Commons.

Political context

The measure revives most of the stalled 2022 Bill C-26 “An Act Respecting Cyber Security” which “died on Paper” when Parliament was prorogued in January 2025, in the wake of former Prime Minister Justin Trudeau’s resignation.

The new government, led by Mark Carney since March 2025, has re-tabled the package with the same two-part structure: (1) amendments to the Telecommunications Act that enable security directions to telecoms; and (2) a new CCSPA setting out mandatory cybersecurity duties for designated operators. This blog focuses on the latter.

If enacted, Canada will join fellow Five Eyes partners such as the United Kingdom and Australia, which already impose statutory cyber-security duties on operators of critical national infrastructure.

The case for new cybersecurity legislation in Canada

The Canadian cyber threat landscape has expanded. The country's national cyber authority, the Canadian Centre for Cybersecurity (Cyber Centre), recently assessed that the number of cyber incidents has “sharply increased” in the last two years, as has the severity of those incidents, with essential services providers among the targets. Likewise, in its 2025-2026 National Cyber Threat Assessment, the Cyber Centre warned that AI technologies are “amplifying cyberspace threats” by lowering barriers to entry, improving the speed and sophistication of social-engineering attacks and enabling more precise operations.

This context mirrors what we are seeing globally: adversaries, including state actors, are taking advantage of the availability and sophistication of AI tools, which they have leverage to amplify the effectiveness of their operations. In this increasingly complex landscape, regulation must keep pace and evolve in step with the risk.

What the Canadian Critical Cyber Systems Protection Act aims to achieve

  • If enacted, the CCSPA will apply to operators in federally regulated critical infrastructure sectors which are vital to national security and public safety, as further defined in “Scope” below (the “Regulated Entities”), to adopt and comply with a minimum standard of cybersecurity duties (further described below)  which align with those its Five Eyes counterparts are already adhering to.

Who does the CCSPA apply to

The CCSPA would apply to designated operators that deliver services or systems within federal jurisdiction in the following priority areas:

  • telecommunications services
  • interprovincial or international pipeline and power line systems, nuclear energy systems, transportation systems
  • banking and clearing  
  • settlement systems

The CCSPA would also grant the Governor in Council (Federal Cabinet) with powers to add or remove entities in scope via regulation.

Scope of the CCSPA

The CCSPA introduces two key instruments:

First, it strengthens cyber threat information sharing between responsible ministers, sector regulators, and the Communications Security Establishment (through the Cyber Centre).

Second, it empowers the Governor in Council (GIC) to issue Cyber Security Directions (CSDs) - binding orders requiring a designated operator to implement specified measures to protect a critical cyber system within defined timeframes.

CSDs may be tailored to an individual operator or applied to a class of operators and can address technology, process, or supplier risks. To safeguard security and commercial confidentiality, the CCSPA restricts disclosure of the existence or content of a CSD except as necessary to carry it out.

Locating decision-making with the GIC ensures that CSDs are made with a cross-government view that weighs national security, economic priorities and international agreement.

New obligations for designated providers

The CCSPA would impose key cybersecurity compliance and obligations on designated providers. As it stands, this includes:

  1. Establishing and maintaining cybersecurity programs: these will need to be comprehensive, proportionate and developed proactively. Once implemented, they will need to be continuously reviewed
  2. Mitigating supply chain risks: Regulated Entities will be required to assess their third-party products and services by conducting a supply chain analysis, and take active steps to mitigate any identified risks
  3. Reporting incidents:  Regulated Entities will need to be more transparent with their reporting, by making the Communications Security Establishment (CSE) aware of any incident which has, or could potentially have, an impact on a critical system. The reports must be made within specific timelines, but in any event within no more than 72 hours;
  4. Compliance with cybersecurity directions:  the government will, under the CCSPA, have the authority to issue cybersecurity directives in an effort to remain responsive to emerging threats, which Regulated Entities will be required to follow once issued
  5. Record keeping: this shouldn’t be a surprise to many of those Regulated Entities which fall in scope, which are already likely to be subject to record keeping requirements. Regulated Entities should expect to be maintaining records and conducting audits of their systems and processes against the requirements of the CCSPA

It should be noted, however, that this may be subject to change, so Regulated Entities should keep an eye on the progress of the Bill as it makes its way through parliament.

Enforcement of the Act would be carried out by sector-specific regulators identified in the Act such as the Office of the Superintendent of Financial Institutions, Minister of Transport, Canada Energy Regulator, Canadian Nuclear Safety Commission and the Ministry of Industry.

What are the penalties for CCSPA non-compliance?

When assessing the penalties associated with non-compliance with the requirements of the CCSPA, it is clear that such non-compliance will be taken seriously, and the severity of the penalties follows the trend of those applied by the European Union to key pieces of EU legislation. The “administrative monetary penalties” (AMPs) set by regulation could see fines being applied of up to C$1 million for individuals and up to C$15 million for organizations.

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