Blog
/
Identity
/
June 9, 2021

Multi-Account Hijack Detection with AI

Discover the analysis of a sophisticated SaaS-based attack using Microsoft 365 accounts. Learn how attackers launch & maintain their offensive strategies.
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
Default blog imageDefault blog imageDefault blog imageDefault blog imageDefault blog imageDefault blog image
09
Jun 2021

The widespread and rapid adoption of Software-as-a-Service (SaaS) has opened up a breadth of security risks for IT teams. Unlike commercial off-the-shelf (COTS) software, SaaS security tends to be managed by third-party vendors rather than the end customer. Security teams therefore struggle with reduced visibility and control over these environments, and cyber-criminals have been quick to take advantage, launching a wave of cloud-based attacks, from Vendor Email Compromise to internal account hijacks.

Attackers often gain access to multiple accounts on the same domain, enabling them to attack from multiple angles, for example sending of hundreds of emails from one account, while maintaining persistence with another. This gives the hacker an opportunity to try multiple attack vectors, using tools native to the SaaS environment as well as external payloads.

While preventative controls such as Multi-Factor Authentication (MFA) provide an extra layer of protection, there are many techniques available to circumvent zero-trust approaches. Remote and flexible working is set to continue to varying degrees across many different regions and industries, so companies must now commit to securing their cloud architecture and developing proactive cyber security measures.

In this blog, we will analyze a persistent cyber-attack which targeted a real estate company in Europe and leveraged several compromised Microsoft 365 accounts. These SaaS takeovers are quickly becoming the new norm, but they are still misunderstood and poorly documented in the wider industry. Cyber AI detected every stage of this intrusion in real time, without the use of signatures or static rules.

A and B: Hijacking Microsoft 365 accounts

The organization had around 5,000 devices in its environment, with 1,000 active SaaS accounts. The timeline below shows how the threat actor leveraged the SaaS accounts of five different users to carry out the operation, as well as exploiting several other accounts on the final day.

Figure 1: Diagram of the infection chain, which occurred over three days. On the fourth day, the attacker tried again but was unsuccessful.

The actor initially compromised at least two SaaS credentials – which we’ll refer to here simply as ‘account A’ and ‘account B’ – and logged in from several unusual geographical locations, presumably using a VPN. Darktrace detected this as unusual login events for the SaaS accounts.

In account A, the attacker was observed previewing files likely to contain customer information, but did not perform any other follow-up activity. In account B, they set a new inbox rule three hours after the initial compromise, resulting in a high-severity alert.

At around this time, the threat actor sent a number of phishing emails from account B: emails that appeared to be sharing a harmless and legitimate-looking folder on OneDrive. The link probably led to a fake Microsoft login page, similar to the below, which could have recorded the victims’ credentials and sent them directly back to the attacker.

Figure 2: A seemingly legitimate Microsoft login page.

The phishing attempt was detected by Antigena Email, Darktrace’s email security technology. Antigena was in passive mode at the time, and so was not configured to take action on these threatening emails. But taking into account the highly anomalous sender surge coupled with the unusual login locations, it would have autonomously intercepted all the emails, reducing the impact of the attack.

The attacker was subsequently locked out of account B. After this, they tried (and failed) to use a legacy user agent to bypass any MFA which may have been enforced on the account. Darktrace detected this as a suspicious login and blocked the attempt.

Accounts C, D and E: The threat develops

The next day, the actor logged into a new account (account C) from the same autonomous system number (ASN), indicating that the account had been infected by the OneDrive phishing emails. In other words, the attacker had leveraged account B to compromise new users in the organization and ensure multiple points of intrusion.

Darktrace detected each stage of this, piecing together the different events into one meaningful security narrative.

Figure 3: Anomalous activity from accounts C, D, and E.

Account C was then used to preview a file likely containing contact information.

After being locked out of account C when trying to log in the next day, the hacker worked their way through two more accounts (account D and account E), which they had hijacked in the previous phishing attempts. They were locked out each time after generating alerts due to the unusual logins and new inbox rules created around the same time.

A to Z: End of the line

Running out of options, the attacker decided to go back to account A and set a new inbox rule, using it to send new phishing emails with a link to a non-Microsoft cloud storage domain (Tresorit). Again, Darktrace recognized this as highly unusual behavior, and the hacker was promptly locked out of the account.

During this burst of activity, Darktrace also observed a Microsoft Teams session from one of the suspicious ASNs. This was likely a social engineering attempt and another possible attack vector. Microsoft Teams could have been leveraged to share a malicious link over instant message, extract sensitive information, or send spam internally and externally on the chat function.

The threat actor could have then used this to pivot across various applications and accounts, assuming that the company had a siloed security approach – with different tools for cloud, SaaS, email, and endpoint – and so could not pick up on the malicious cross-platform movement.

On the following day, the attacker attempted logins on multiple accounts again, but with no success. Cyber AI had pinpointed all the anomalous activity – no matter where it originated – and alerted the security team immediately.

SaaS attack under the microscope

Multi-account compromises can be incredibly persistent and are difficult for traditional security tools to identify. The hacker used several tactics to circumvent the customer’s existing email security products:

  1. The initial use of two compromised credentials – account A and account B – allowed the hacker to stay under the radar and not raise too much suspicion on a single account. Account A was kept quiet until other avenues had been exhausted.
  2. Activity was generated from multiple ASNs in at least three different geographical locations, probably utilizing a VPN: one in Africa where much of the activity originated, and two in North America, including some widely used ASNs which were highly unusual for the customer.
  3. The attacker entirely used Microsoft services until the final emails, choosing to ‘live off the land’ rather than sending links that may have been caught by gateways.
  4. The attacker logged into Microsoft Teams in their final movements – a fairly benign-looking event which could have been used to compromise more accounts and move laterally, and would have gone undetected.

Darktrace identified every stage of the attack – including spotting the anomalous ASNs – and launched an automatic, in-depth investigation with Cyber AI Analyst. The organization was thus able to take action before the damage was done.

Figure 4: Darktrace’s SaaS console gives a clear overview of activity across all different applications.

ABCs of SaaS security

The approach of using various accounts to mount the offensive, while keeping one to maintain persistence, prolonged this intrusion. Such tactics will likely be seen again in the near future.

Tracking the number of factors involved in an attack with multiple credentials, multiple attack vectors, and multiple attacker-IPs, is a serious challenge. In these situations, it is essential to have a security solution which can detect activity across different applications, forming a unified and holistic understanding over the entire digital enterprise.

While not active in this case, Antigena SaaS would have taken autonomous action and prevented the threat from escalating by enforcing normal behavior, stopping the hacker from logging in from malicious infrastructure or performing any out-of-character SaaS actions, such as creating new inbox rules.

Following the intrusion, the company decided to adopt Antigena SaaS, which now mitigates their cloud security risks and guards against sensitive data loss and reputational damage.

Thanks to Darktrace analyst Daniel Gentle for his insights on the above threat find.

Darktrace model detections:

  • SaaS / Compromise / Unusual Login and New Email Rule
  • SaaS / Compliance / New Email Rule
  • SaaS / Unusual Activity / Unusual External Source for SaaS Credential Use
  • SaaS / Access / Suspicious Login Attempt
  • Antigena Email: Unusual Login Location + Sender Surge
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

More in this series

No items found.

Blog

/

/

May 8, 2025

Anomaly-based threat hunting: Darktrace's approach in action

person working on laptopDefault blog imageDefault blog image

What is threat hunting?

Threat hunting in cybersecurity involves proactively and iteratively searching through networks and datasets to detect threats that evade existing automated security solutions. It is an important component of a strong cybersecurity posture.

There are several frameworks that Darktrace analysts use to guide how threat hunting is carried out, some of which are:

  • MITRE Attack
  • Tactics, Techniques, Procedures (TTPs)
  • Diamond Model for Intrusion Analysis
  • Adversary, Infrastructure, Victims, Capabilities
  • Threat Hunt Model – Six Steps
  • Purpose, Scope, Equip, Plan, Execute, Feedback
  • Pyramid of Pain

These frameworks are important in baselining how to run a threat hunt. There are also a combination of different methods that allow defenders diversity– regardless of whether it is a proactive or reactive threat hunt. Some of these are:

  • Hypothesis-based threat hunting
  • Analytics-driven threat hunting
  • Automated/machine learning hunting
  • Indicator of Compromise (IoC) hunting
  • Victim-based threat hunting

Threat hunting with Darktrace

At its core, Darktrace relies on anomaly-based detection methods. It combines various machine learning types that allows it to characterize what constitutes ‘normal’, based on the analysis of many different measures of a device or actor’s behavior. Those types of learning are then curated into what are called models.

Darktrace models leverage anomaly detection and integrate outputs from Darktrace Deep Packet Inspection, telemetry inputs, and additional modules, creating tailored activity detection.

This dynamic understanding allows Darktrace to identify, with a high degree of precision, events or behaviors that are both anomalous and unlikely to be benign.  On top of machine learning models for detection, there is also the ability to change and create models showcasing the tool’s diversity. The Model Editor allows security teams to specify values, priorities, thresholds, and actions they want to detect. That means a team can create custom detection models based on specific use cases or business requirements. Teams can also increase the priority of existing detections based on their own risk assessments to their environment.

This level of dexterity is particularly useful when conducting a threat hunt. As described above, and in previous ‘Inside the SOC’ blogs such a threat hunt can be on a specific threat actor, specific sector, or a  hypothesis-based threat hunt combined with ‘experimenting’ with some of Darktrace’s models.

Conducting a threat hunt in the energy sector with experimental models

In Darktrace’s recent Threat Research report “AI & Cybersecurity: The state of cyber in UK and US energy sectors” Darktrace’s Threat Research team crafted hypothesis-driven threat hunts, building experimental models and investigating existing models to test them and detect malicious activity across Darktrace customers in the energy sector.

For one of the hunts, which hypothesised utilization of PerfectData software and multi-factor authentication (MFA) bypass to compromise user accounts and destruct data, an experimental model was created to detect a Software-as-a-Service (SaaS) user performing activity relating to 'PerfectData Software’, known to allow a threat actor to exfiltrate whole mailboxes as a PST file. Experimental model alerts caused by this anomalous activity were analyzed, in conjunction with existing SaaS and email-related models that would indicate a multi-stage attack in line with the hypothesis.

Whilst hunting, Darktrace researchers found multiple model alerts for this experimental model associated with PerfectData software usage, within energy sector customers, including an oil and gas investment company, as well as other sectors. Upon further investigation, it was also found that in June 2024, a malicious actor had targeted a renewable energy infrastructure provider via a PerfectData Software attack and demonstrated intent to conduct an Operational Technology (OT) attack.

The actor logged into Azure AD from a rare US IP address. They then granted Consent to ‘eM Client’ from the same IP. Shortly after, the actor granted ‘AddServicePrincipal’ via Azure to PerfectData Software. Two days later, the actor created a  new email rule from a London IP to move emails to an RSS Feed Folder, stop processing rules, and mark emails as read. They then accessed mail items in the “\Sent” folder from a malicious IP belonging to anonymization network,  Private Internet Access Virtual Private Network (PIA VPN) [1]. The actor then conducted mass email deletions, deleting multiple instances of emails with subject “[Name] shared "[Company Name] Proposal" With You” from the  “\Sent folder”. The emails’ subject suggests the email likely contains a link to file storage for phishing purposes. The mass deletion likely represented an attempt to obfuscate a potential outbound phishing email campaign.

The Darktrace Model Alert that triggered for the mass deletes of the likely phishing email containing a file storage link.
Figure 1: The Darktrace Model Alert that triggered for the mass deletes of the likely phishing email containing a file storage link.

A month later, the same user was observed downloading mass mLog CSV files related to proprietary and Operational Technology information. In September, three months after the initial attack, another mass download of operational files occurred by this actor, pertaining to operating instructions and measurements, The observed patience and specific file downloads seemingly demonstrated an intent to conduct or research possible OT attack vectors. An attack on OT could have significant impacts including operational downtime, reputational damage, and harm to everyday operations. Darktrace alerted the impacted customer once findings were verified, and subsequent actions were taken by the internal security team to prevent further malicious activity.

Conclusion

Harnessing the power of different tools in a security stack is a key element to cyber defense. The above hypothesis-based threat hunt and custom demonstrated intent to conduct an experimental model creation demonstrates different threat hunting approaches, how Darktrace’s approach can be operationalized, and that proactive threat hunting can be a valuable complement to traditional security controls and is essential for organizations facing increasingly complex threat landscapes.

Credit to Nathaniel Jones (VP, Security & AI Strategy, Field CISO at Darktrace) and Zoe Tilsiter (EMEA Consultancy Lead)

References

  1. https://spur.us/context/191.96.106.219

Continue reading
About the author
Nathaniel Jones
VP, Security & AI Strategy, Field CISO

Blog

/

/

May 6, 2025

Combatting the Top Three Sources of Risk in the Cloud

woman working on laptopDefault blog imageDefault blog image

With cloud computing, organizations are storing data like intellectual property, trade secrets, Personally Identifiable Information (PII), proprietary code and statistics, and other sensitive information in the cloud. If this data were to be accessed by malicious actors, it could incur financial loss, reputational damage, legal liabilities, and business disruption.

Last year data breaches in solely public cloud deployments were the most expensive type of data breach, with an average of $5.17 million USD, a 13.1% increase from the year before.

So, as cloud usage continues to grow, the teams in charge of protecting these deployments must understand the associated cybersecurity risks.

What are cloud risks?

Cloud threats come in many forms, with one of the key types consisting of cloud risks. These arise from challenges in implementing and maintaining cloud infrastructure, which can expose the organization to potential damage, loss, and attacks.

There are three major types of cloud risks:

1. Misconfigurations

As organizations struggle with complex cloud environments, misconfiguration is one of the leading causes of cloud security incidents. These risks occur when cloud settings leave gaps between cloud security solutions and expose data and services to unauthorized access. If discovered by a threat actor, a misconfiguration can be exploited to allow infiltration, lateral movement, escalation, and damage.

With the scale and dynamism of cloud infrastructure and the complexity of hybrid and multi-cloud deployments, security teams face a major challenge in exerting the required visibility and control to identify misconfigurations before they are exploited.

Common causes of misconfiguration come from skill shortages, outdated practices, and manual workflows. For example, potential misconfigurations can occur around firewall zones, isolated file systems, and mount systems, which all require specialized skill to set up and diligent monitoring to maintain

2. Identity and Access Management (IAM) failures

IAM has only increased in importance with the rise of cloud computing and remote working. It allows security teams to control which users can and cannot access sensitive data, applications, and other resources.

Cybersecurity professionals ranked IAM skills as the second most important security skill to have, just behind general cloud and application security.

There are four parts to IAM: authentication, authorization, administration, and auditing and reporting. Within these, there are a lot of subcomponents as well, including but not limited to Single Sign-On (SSO), Two-Factor Authentication (2FA), Multi-Factor Authentication (MFA), and Role-Based Access Control (RBAC).

Security teams are faced with the challenge of allowing enough access for employees, contractors, vendors, and partners to complete their jobs while restricting enough to maintain security. They may struggle to track what users are doing across the cloud, apps, and on-premises servers.

When IAM is misconfigured, it increases the attack surface and can leave accounts with access to resources they do not need to perform their intended roles. This type of risk creates the possibility for threat actors or compromised accounts to gain access to sensitive company data and escalate privileges in cloud environments. It can also allow malicious insiders and users who accidentally violate data protection regulations to cause greater damage.

3. Cross-domain threats

The complexity of hybrid and cloud environments can be exploited by attacks that cross multiple domains, such as traditional network environments, identity systems, SaaS platforms, and cloud environments. These attacks are difficult to detect and mitigate, especially when a security posture is siloed or fragmented.  

Some attack types inherently involve multiple domains, like lateral movement and supply chain attacks, which target both on-premises and cloud networks.  

Challenges in securing against cross-domain threats often come from a lack of unified visibility. If a security team does not have unified visibility across the organization’s domains, gaps between various infrastructures and the teams that manage them can leave organizations vulnerable.

Adopting AI cybersecurity tools to reduce cloud risk

For security teams to defend against misconfigurations, IAM failures, and insecure APIs, they require a combination of enhanced visibility into cloud assets and architectures, better automation, and more advanced analytics. These capabilities can be achieved with AI-powered cybersecurity tools.

Such tools use AI and automation to help teams maintain a clear view of all their assets and activities and consistently enforce security policies.

Darktrace / CLOUD is a Cloud Detection and Response (CDR) solution that makes cloud security accessible to all security teams and SOCs by using AI to identify and correct misconfigurations and other cloud risks in public, hybrid, and multi-cloud environments.

It provides real-time, dynamic architectural modeling, which gives SecOps and DevOps teams a unified view of cloud infrastructures to enhance collaboration and reveal possible misconfigurations and other cloud risks. It continuously evaluates architecture changes and monitors real-time activity, providing audit-ready traceability and proactive risk management.

Real-time visibility into cloud assets and architectures built from network, configuration, and identity and access roles. In this unified view, Darktrace / CLOUD reveals possible misconfigurations and risk paths.
Figure 1: Real-time visibility into cloud assets and architectures built from network, configuration, and identity and access roles. In this unified view, Darktrace / CLOUD reveals possible misconfigurations and risk paths.

Darktrace / CLOUD also offers attack path modeling for the cloud. It can identify exposed assets and highlight internal attack paths to get a dynamic view of the riskiest paths across cloud environments, network environments, and between – enabling security teams to prioritize based on unique business risk and address gaps to prevent future attacks.  

Darktrace’s Self-Learning AI ensures continuous cloud resilience, helping teams move from reactive to proactive defense.

[related-resource]

Continue reading
About the author
Pallavi Singh
Product Marketing Manager, OT Security & Compliance
Your data. Our AI.
Elevate your network security with Darktrace AI