Inside the SOC
To be Xor Not to Be: How RESPOND could have stopped a surprise DDoS incident
When is the best time to be hit with a cyber-attack? The answer that springs to most is ‘Never’, however in today’s threat landscape, this is often wishful thinking. The next best answer is ‘When we’re ready for it’. Yet, this does not take into account the intention of those committing attacks. The reality is that the best time for a cyber-attack is when no one else is around to stop it.
Previous analysis from Mandiant reveals that over half of ransomware compromises occur at out of work hours, a trend Darktrace has also witnessed in the past two years . This is deliberate, as the fewer people that are online, the harder it is to get ahold of security teams and the higher the likelihood there is of an attacker achieving their goals. Given this landscape, it is clear that autonomous response is more important than ever. In the absence of human resources, autonomous security can fill in the gap long enough for IT teams to begin remediation.
This blog will detail an incident where autonomous response provided by Darktrace/RESPOND would have entirely prevented an infection attempt, despite it occurring in the early hours of the morning. Because the customer had RESPOND in human confirmation mode (AI response must first be approved by a human), the attempt by XorDDoS was ultimately successful. Given that the attack occurred in the early hours of the morning, there was likely no one around to confirm Darktrace RESPOND actions and prevent the attack.
XorDDoS is a botnet, a type of malware that infects devices for the purpose of controlling them as a collective to carry out specific actions. In the case of XorDDoS, it infects devices in order to carry out denial of service attacks using said devices. This year, Microsoft has reported a substantial increase in activity from this malware strain, with an increased focus on Linux based operating systems . XorDDoS most commonly finds its way onto systems via SSH brute-forcing, and once deployed, encrypts its traffic with an XOR cipher. XorDDoS has also been known to download additional payloads such as backdoors and cryptominers. Needless to say, this is not something you have on a corporate network.
The incident begins with a device first coming online on 10th August. The device appeared to be internet facing and Darktrace saw hundreds of incoming SSH connections to the device from a variety of endpoints. Over the course of the next five days, the device received thousands of failed SSH connections from several IP addresses that, according to OSINT, may be associated with web scanners . Successful SSH connections were seen from internal IP addresses as well as IP addresses associated with IT solutions relevant to Asia-Pacific (the customer’s geographic location). On midnight of 15th August, the first successful SSH connection occurred from an IP address that has been associated with web scanning. This connection lasted around an hour and a half, and the external IP uploaded around 3.3 MB of data to the client device. Given all of this, and what the industry knows about XorDDoS, it is likely that the client device had SSH exposed to the Internet which was then brute-forced for initial access.
There were a few hours of dwell until the device downloaded a ZIP file from an Iraqi mirror site, mirror[.]earthlink[.]iq at around 6AM in the customer time zone. The endpoint had only been seen once before and was 100% rare for the network. Since there has been no information on OSINT around this particular endpoint or the ZIP files downloaded from the mirror site, the detection was based on the unusualness of the download.
Following this, Darktrace saw the device make a curl request to the external IP address 107.148.210[.]218. This was highlighted as the user agent associated with curl had not been seen on the device before, and the connection was made directly to an IP address without a hostname (suggesting that the connection was scripted). The URIs of these requests were ‘1.txt’ and ‘2.txt’.
The ‘.txt’ extensions on the URIs were deceiving and it turned out that both were executable files masquerading as text files. OSINT on both of the hashes revealed that the files were likely associated with XorDDoS. Additionally, judging from packet captures of the connection, the true file extension appeared to be ‘.ELF’. As XorDDoS primarily affects Linux devices, this would make sense as the true extension of the payload.
Immediately after the ‘.ELF’ download, Darktrace saw the device attempting C2 connections. This included connections to DGA-like domains on unusual ports such as 1525 and 8993. Luckily, the client’s firewall seems to have blocked these connections, but that didn’t stop XorDDoS. XorDDoS continued to attempt connections to C2 domains, which triggered several Proactive Threat Notifications (PTNs) that were alerted by SOC. Following the PTNs, the client manually quarantined the device a few hours after the initial breach. This lapse in actioning was likely due to an early morning timing with the customer’s employees not being online yet. After the device was quarantined, Darktrace still saw XorDDoS attempting C2 connections. In all, hundreds of thousands of C2 connections were detected before the device was removed from the network sometime on 7th September.
An Alternate Timeline
Although the device was ultimately removed, this attack would have been entirely prevented had RESPOND/Network not been in human confirmation mode. Autonomous response would have kicked in once the device downloaded the ‘.ZIP file’ from the Iraqi mirror site and blocked all outgoing connections from the breach device for an hour:
The model breach in Figure 3 would have prevented the download of the XorDDoS executables, and then prevented the subsequent C2 connections. This hour would have been crucial, as it would have given enough time for members of the customer’s security team to get back online should the compromised device have attempted anything else. With everyone attentive, it is unlikely that this activity would have lasted as long as it did. Had the attack been allowed to progress further, the infected device would have at the very least been an unwilling participant in a future DDoS attack. Additionally, the device could have a backdoor placed within it, and additional malware such as cryptojackers might have been deployed.
Unfortunately, we do not exist in the alternate timeline that autonomous response would have prevented this whole series of events.Luckily, although it was not in place, the PTN alerts provided by Darktrace’s SOC team still sped up the process of remediation in an event that was never intended to be discovered given the time it occurred. Unusual times of attack are not just limited to ransomware, so organizations need to have measures in place for the times that are most inconvenient to them, but most convenient to attackers. With Darktrace/RESPOND however, this is just one click away.
Thanks to Brianna Leddy for their contribution.
Darktrace Model Detections
Below is a list of model breaches in order of trigger. The Proactive Threat Notification models are in bold and only the first Antigena [RESPOND] breach that would have prevented the initial compromise has been included. A manual quarantine breach has also been added to show when the customer began remediation.
- Compliance / Incoming SSH, August 12th 23:39 GMT +8
- Anomalous File / Zip or Gzip from Rare External Location, August 15th, 6:07 GMT +8
- Antigena / Network / External Threat / Antigena File then New Outbound Block, August 15th 6:36 GMT +8 [part of the RESPOND functionality]
- Anomalous Connection / New User Agent to IP Without Hostname, August 15th 6:59 GMT +8
- Anomalous File / Numeric Exe Download, August 15th 6:59 GMT +8
- Anomalous File / Masqueraded File Transfer, August 15th 6:59 GMT +8
- Anomalous File / EXE from Rare External Location, August 15th 6:59 GMT +8
- Device / Internet Facing Device with High Priority Alert, August 15th 6:59 GMT +8
- Compromise / Rare Domain Pointing to Internal IP, August 15th 6:59 GMT +8
- Device / Initial Breach Chain Compromise, August 15th 6:59 GMT +8
- Compromise / Large Number of Suspicious Failed Connections, August 15th 7:01 GMT +8
- Compromise / High Volume of Connections with Beacon Score, August 15th 7:04 GMT +8
- Compromise / Fast Beaconing to DGA, August 15th 7:04 GMT +8
- Compromise / Suspicious File and C2, August 15th 7:04 GMT +8
- Antigena / Network / Manual / Quarantine Device, August 15th 8:54 GMT +8 [part of the RESPOND functionality]
List of IOCs
MITRE ATT&CK Mapping
 They Come in the Night: Ransomware Deployment Trends
 Rise in XorDdos: A deeper look at the stealthy DDoS malware targeting Linux devices
 Alien Vault: Domain Navicatadvvr & https://www.virustotal.com/gui/domain/navicatadvvr.com & https://maltiverse.com/hostname/navicatadvvr.com
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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 .
Malicious actors typically gain entry to organizations’ Microsoft 365 environments by abusing either stolen account credentials or stolen session cookies . 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 . 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.
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.
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.
MITRE ATT&CK Mapping
• T1598 – Phishing for Information
• T1110 – Brute Force
• T1078.004 – Valid Accounts: Cloud Accounts
Command and Control:
• T1105 – Ingress Tool Transfer
• T1098.003 – Account Manipulation: Additional Cloud Roles
• T1114 – Email Collection
• T1564.008 – Hide Artifacts: Email Hiding Rules
• 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)
Darktrace Integrates Self-Learning AI with Amazon Security Lake to Support Security Investigations
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.