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Cloud
SaaS security risks: Detecting a multi-account hijack with AI
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:
- 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.
- 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.
- 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.
- 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
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Inside the SOC
How Abuse of ‘PerfectData Software’ May Create a Perfect Storm: An Emerging Trend in Account Takeovers
Amidst the ever-changing threat landscape, new tactics, techniques, and procedures (TTPs) seem to emerge daily, creating extreme challenges for security teams. The broad range of attack methods utilized by attackers seems to present an insurmountable problem: how do you defend against a playbook that does not yet exist?
Faced with the growing number of novel and uncommon attack methods, it is essential for organizations to adopt a security solution able to detect threats based on their anomalies, rather than relying on threat intelligence alone.
In March 2023, Darktrace observed an emerging trend in the use of an application known as ‘PerfectData Software’ for probable malicious purposes in several Microsoft 365 account takeovers.
Using its anomaly-based detection, Darktrace DETECT™ was able to identify the activity chain surrounding the use of this application, potentially uncovering a novel piece of threat actor tradecraft in the process.
Microsoft 365 Intrusions
In recent years, Microsoft’s Software-as-a-Service (SaaS) suite, Microsoft 365, along with its built-in identity and access management (IAM) service, Azure Active Directory (Azure AD), have been heavily targeted by threat actors due to their near-ubiquitous usage across industries. Four out of every five Fortune 500 companies, for example, use Microsoft 365 services [1].
Malicious actors typically gain entry to organizations’ Microsoft 365 environments by abusing either stolen account credentials or stolen session cookies [2]. Once inside, actors can access sensitive data within mailboxes or SharePoint repositories, and send out emails or Teams messages. This activity can often result in serious financial harm, especially in cases where the malicious actor’s end-goal is to elicit fraudulent transactions.
Darktrace regularly observes malicious actors behaving in predictable ways once they gain access to customer Microsoft 365 environment. One typical example is the creation of new inbox rules and sending deceitful emails intended to convince recipients to carry out subsequent actions, such as following a malicious link or providing sensitive information. It is also common for actors to register new applications in Azure AD so that they can be used to conduct follow-up activities, like mass-mailing or data theft. The registration of applications in Azure AD therefore seems to be a relatively predictable threat actor behavior [3][4]. Darktrace DETECT understands that unusual application registrations in Azure AD may constitute a deviation in expected behavior, and therefore a possible indicator of account compromise.
These registrations of applications in Azure AD are evidenced by creations of, as well as assignments of permissions to, Service Principals in Azure AD. Darktrace has detected a growing trend in actors creating and assigning permissions to a Service Principal named ‘PerfectData Software’. Further investigation of this Azure AD activity revealed it to be part of an ongoing account takeover.
‘PerfectData Software’ Activity
Darktrace observed variations of the following pattern of activity relating to an application named ‘PerfectData Software’ within its customer base:
- Actor signs in to a Microsoft 365 account from an endpoint associated with a Virtual Private Server (VPS) or Virtual Private Network (VPN) service
- Actor registers an application called 'PerfectData Software' with Azure AD, and then grants permissions to the application
- Actor accesses mailbox data and creates inbox rule
In two separate incidents, malicious actors were observed conducting their activities from endpoints associated with VPN services (HideMyAss (HMA) VPN and Surfshark VPN, respectively) and from endpoints within the Autonomous System AS396073 MAJESTIC-HOSTING-01.
In March 2023, Darktrace observed a malicious actor signing in to a Microsoft 365 account from a Kuwait-based IP address within the Autonomous System, AS198605 AVAST Software s.r.o. This IP address is associated with the VPN service, HMA VPN. Over the next couple of days, an actor (likely the same malicious actor) signed in to the account several more times from two different Nigeria-based endpoints, as well as a VPS-related endpoint and a HMA VPN endpoint.
During their login sessions, the actor performed a variety of actions. First, they created and assigned permissions to a Service Principal named ‘PerfectData Software’. This Service Principal creation represents the registration of an application called ‘PerfectData Software’ in Azure AD. Although the reason for registering this application is unclear, within a few days the actor registered and granted permission to another application, ‘Newsletter Software Supermailer’, and created a new inbox rule names ‘s’ on the mailbox of the hijacked account. This inbox rule moved emails meeting certain conditions to a folder named ‘RSS Subscription. The ‘Newsletter Software Supermailer’ application was likely registered by the actor to facilitate mass-mailing activity.
Immediately after these actions, Darktrace detected the actor sending out thousands of malicious emails from the account. The emails included an attachment named ‘Credit Transfer Copy.html’, which contained a suspicious link. Further investigation revealed that the customer’s network had received several fake invoice emails prior to this initial intrusion activity. Additionally, there was an unusually high volume of failed logins to the compromised account around the time of the initial access.
In a separate case also observed by Darktrace in March 2023, a malicious actor was observed signing in to a Microsoft 365 account from an endpoint within the Autonomous System, AS397086 LAYER-HOST-HOUSTON. The endpoint appears to be related to the VPN service, Surfshark VPN. This login was followed by several failed and successful logins from a VPS-related within the Autonomous System, AS396073 MAJESTIC-HOSTING-01. The actor was then seen registering and assigning permissions to an application called ‘PerfectData Software’. As with the previous example, the motives for this registration are unclear. The actor proceeded to log in several more times from a Surfshark VPN endpoint, however, they were not observed carrying out any further suspicious activity.
It was not clear in either of these examples, nor in fact any of cases observed by Darktrace, why actors had registered and assigned permissions to an application called ‘PerfectData Software’, and there do not appear to be any open-source intelligence (OSINT) resources or online literature related to the malicious usage of an application by that name. That said, there are several websites which appear to provide email migration and data recovery/backup tools under the moniker ‘PerfectData Software’.
It is unclear whether the use of ‘PerfectData Software’ by malicious actors observed on the networks of Darktrace customers was one of these tools. However, given the nature of the tools, it is possible that the actors intended to use them to facilitate the exfiltration of email data from compromises mailboxes.
If the legitimate software ‘PerfectData’ is the application in question in these incidents, it is likely being purchased and misused by attackers for malicious purposes. It is also possible the application referenced in the incidents is a spoof of the legitimate ‘PerfectData’ software designed to masquerade a malicious application as legitimate.
Darktrace Coverage
Cases of ‘PerfectData Software’ activity chains detected by Darktrace typically began with an actor signing into an internal user’s Microsoft 365 account from a VPN or VPS-related endpoint. These login events, along with the suspicious email and/or brute-force activity which preceded them, caused the following DETECT models to breach:
- SaaS / Access / Unusual External Source for SaaS Credential Use
- SaaS / Access / Suspicious Login Attempt
- SaaS / Compromise / Login From Rare Following Suspicious Login Attempt(s)
- SaaS / Email Nexus / Unusual Location for SaaS and Email Activity
Subsequent activities, including inbox rule creations, registration of applications in Azure AD, and mass-mailing activity, resulted in breaches of the following DETECT models.
- SaaS / Admin / OAuth Permission Grant
- SaaS / Compromise / Unusual Logic Following OAuth Grant
- SaaS / Admin / New Application Service Principal
- IaaS / Admin / Azure Application Administration Activities
- SaaS / Compliance / New Email Rule
- SaaS / Compromise / Unusual Login and New Email Rule
- SaaS / Email Nexus / Suspicious Internal Exchange Activity
- SaaS / Email Nexus / Possible Outbound Email Spam
- SaaS / Compromise / Unusual Login and Outbound Email Spam
- SaaS / Compromise / Suspicious Login and Suspicious Outbound Email(s)
In cases where Darktrace RESPOND™ was enabled in autonomous response mode, ‘PerfectData Software’ activity chains resulted in breaches of the following RESPOND models:
• Antigena / SaaS / Antigena Suspicious SaaS Activity Block
• Antigena / SaaS / Antigena Significant Compliance Activity Block
In response to these model breaches, Darktrace RESPOND took immediate action, performing aggressive, inhibitive actions, such as forcing the actor to log out of the SaaS platform, and disabling the user entirely. When applied autonomously, these RESPOND actions would seriously impede an attacker’s progress and minimize network disruption.
In addition, Darktrace Cyber AI Analyst was able to autonomously investigate registrations of the ‘PerfectData Software’ application and summarized its findings into digestible reports.
Conclusion
Due to the widespread adoption of Microsoft 365 services in the workplace and continued emphasis on a remote workforce, account hijackings now pose a more serious threat to organizations around the world than ever before. The cases discussed here illustrate the tendency of malicious actors to conduct their activities from endpoints associated with VPN services, while also registering new applications, like PerfectData Software, with malicious intent.
While it was unclear exactly why the malicious actors were using ‘PerfectData Software’ as part of their account hijacking, it is clear that either the legitimate or spoofed version of the application is becoming an very likely emergent piece of threat actor tradecraft.
Darktrace DETECT’s anomaly-based approach to threat detection allowed it to recognize that the use of ‘PerfectData Software’ represented a deviation in the SaaS user’s expected behavior. While Darktrace RESPOND, when enabled in autonomous response mode, was able to quickly take preventative action against threat actors, blocking the potential use of the application for data exfiltration or other nefarious purposes.
Appendices
MITRE ATT&CK Mapping
Reconnaissance:
• T1598 – Phishing for Information
Credential Access:
• T1110 – Brute Force
Initial Access:
• T1078.004 – Valid Accounts: Cloud Accounts
Command and Control:
• T1105 – Ingress Tool Transfer
Persistence:
• T1098.003 – Account Manipulation: Additional Cloud Roles
Collection:
• T1114 – Email Collection
Defense Evasion:
• T1564.008 – Hide Artifacts: Email Hiding Rules
Lateral Movement:
• T1534 – Internal Spearphishing
Unusual Source IPs
• 5.62.60[.]202 (AS198605 AVAST Software s.r.o.)
• 160.152.10[.]215 (AS37637 Smile-Nigeria-AS)
• 197.244.250[.]155 (AS37705 TOPNET)
• 169.159.92[.]36 (AS37122 SMILE)
• 45.62.170[.]237 (AS396073 MAJESTIC-HOSTING-01)
• 92.38.180[.]49 (AS202422 G-Core Labs S.A)
• 129.56.36[.]26 (AS327952 AS-NATCOM)
• 92.38.180[.]47 (AS202422 G-Core Labs S.A.)
• 107.179.20[.]214 (AS397086 LAYER-HOST-HOUSTON)
• 45.62.170[.]31 (AS396073 MAJESTIC-HOSTING-01)
References
[1] https://www.investing.com/academy/statistics/microsoft-facts/
[2] https://intel471.com/blog/countering-the-problem-of-credential-theft
[3] https://darktrace.com/blog/business-email-compromise-to-mass-phishing-campaign-attack-analysis
[4] https://darktrace.com/blog/breakdown-of-a-multi-account-compromise-within-office-365
Blog
Cloud
Darktrace Integrates Self-Learning AI with Amazon Security Lake to Support Security Investigations
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Darktrace has deepened its relationship with AWS by integrating its detection and response capabilities with Amazon Security Lake.
This development will allow mutual customers to seamlessly combine Darktrace AI’s bespoke understanding of their organization with the Threat Intelligence offered by other security tools, and investigate all of their alerts in one central location.
This integration will improve the value security teams get from both products, streamlining analyst workflows and improving their ability to detect and respond to the full spectrum of known and unknown cyber-threats.
How Darktrace and Amazon Security Lake augment security teams
Amazon Security Lake is a newly-released service that automatically centralizes an organization’s security data from cloud, on-premises, and custom sources into a customer owned purpose-built data lake. Both Darktrace and Amazon Security Lake support the Open Cybersecurity Schema Framework (OCSF), an open standard to simplify, combine, and analyze security logs.
Customers can store security logs, events, alerts, and other relevant data generated by various AWS services and security tools. By consolidating security data in a central lake, organizations can gain a holistic view of their security posture, perform advanced analytics, detect anomalies and open investigations to improve their security practices.
With Darktrace DETECT and RESPOND AI engines covering all assets across IT, OT, network, endpoint, IoT, email and cloud, organizations can augment the value of their security data lakes by feeding Darktrace’s rich and context-aware datapoints to Amazon Security Lake.
Amazon Security Lake empowers security teams to improve the protection of your digital estate:
- Quick and painless data normalization
- Fast-tracks ability to investigate, triage and respond to security events
- Broader visibility aids more effective decision-making
- Surfaces and prioritizes anomalies for further investigation
- Single interface for seamless data management
How will Darktrace customers benefit?
Across the Cyber AI Loop, all Darktrace solutions have been architected with AWS best practices in mind. With this integration, Darktrace is bringing together its understanding of ‘self’ for every organization with the centralized data visibility of the Amazon Security Lake. Darktrace’s unique approach to cyber security, powered by groundbreaking AI research, delivers a superior dataset based on a deep and interconnected understanding of the enterprise.
Where other cyber security solutions are trained to identify threats based on historical attack data and techniques, Darktrace DETECT gains a bespoke understanding of every digital environment, continuously analyzing users, assets, devices and the complex relationships between them. Our AI analyzes thousands of metrics to reveal subtle deviations that may signal an evolving issue – even unknown techniques and novel malware. It distinguishes between malicious and benign behavior, identifying harmful activity that typically goes unnoticed. This rich dataset is fed into RESPOND, which takes precise action to neutralize threats against any and every asset, no matter where data resides.
Both DETECT and RESPOND are supported by Darktrace Self-Learning AI, which provides full, real-time visibility into an organization’s systems and data. This always-on threat analysis already makes humans better at cyber security, improving decisions and outcomes based on total visibility of the digital ecosystem, supporting human performance with AI coverage and empowering security teams to proactively protect critical assets.
Converting Darktrace alerts to the Amazon Security Lake Open Cybersecurity Schema Framework (OCSF) supplies the Security Operations Center (SOC) and incident response team with contextualized data, empowering them to accelerate their investigation, triage and response to potential cyber threats.
Darktrace is available for purchase on the AWS Marketplace.
Learn more about how Darktrace provides full-coverage, AI-powered cloud security for AWS, or see how our customers use Darktrace in their AWS cloud environments.
