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August 5, 2025

2025 Cyber Threat Landscape: Darktrace’s Mid-Year Review

Explore key cyber threat trends observed across Darktrace’s customer base in the first half of 2025. As threat actors increasingly adopt AI and diversify their techniques and tooling, anomaly-based detection continues to prove vital in defending against evolving attacks.
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
Emma Foulger
Global Threat Research Operations Lead
cyberseucity 2025 half year threat report Default blog imageDefault blog imageDefault blog imageDefault blog imageDefault blog imageDefault blog image
05
Aug 2025

2025: Threat landscape in review

The following is a retrospective of the first six months of 2025, highlighting key findings across the threat landscape impacting Darktrace customers.

Darktrace observed a wide range of tactics during this period, used by various types of threat actors including advanced persistent threats (APTs), Malware-as-a-Service (MaaS) and Ransomware-as-a-Service (RaaS) groups.

Methodology

Darktrace’s Analyst team conduct investigations and research into threats facing organizations and security teams across our customer base.  This includes direct investigations with our 24/7 Security Operations Centre (SOC), via services such as Managed Detection and Response (MDR) and Managed Threat Detection, as well as broader cross-fleet research through our Threat Research function.

At the core of our research is Darktrace’s anomaly-based detection, which the Analyst team contextualizes and analyzes to provide additional support to customers and deepen our understanding of the threats they face.

Threat actors are incorporating AI into offensive operations

Threat actors are continuously evolving their tactics, techniques, and procedures (TTPs), posing an ongoing challenge to effective defense hardening. Increasingly, many threat actors are adopting AI, particularly large language models (LLMs), into their operations to enhance the scale, sophistication, and efficacy of their attacks.

The evolving functionality of malware, such as the recently reported LameHug malware by CERT-UA, which uses an open-source LLM, exemplifies this observation [1].

Threat landscape trends in 2025

Threat actors applying AI to Email attacks

LLMs present a clear opportunity for attackers to take advantage of AI and create effective phishing emails at speed. While Darktrace cannot definitively confirm the use of AI to create the phishing emails observed across the customer base, the high volume of phishing emails and notable shifts in tactic could potentially be explained by threat actors adopting new tooling such as LLMs.

  • The total number of malicious emails detected by Darktrace from January to May 2025 was over 12.6 million
  • VIP users continue to face significant threat, with over 25% of all phishing emails targeting these users in the first five months of 2025
  • QR code-based phishing emails have remained a consistent tactic, with a similar proportion observed in January-May 2024 and 2025. The highest numbers were observed in February 2025, with over 1 million detected in that month alone.
  • Shifts towards increased sophistication within phishing emails are emerging, with a year-on-year increase in the proportion of phishing emails containing either a high text volume or multistage payloads. In the first five months of 2025, 32% of phishing emails contained a high volume of text.

The increase in proportion of phishing emails with a high volume of text in particular could point towards threat actors leveraging LLMs to create phishing emails with large, but believable, text in an easy and efficient way.

The above email statistics are derived from analysis of monitored Darktrace / EMAIL model data for all customer deployments hosted in the cloud between January 1 and May 31, 2025.

Campaign Spotlight: Simple, Quick - ClickFix

An interesting technique Darktrace observed multiple times throughout March and April was ClickFix social engineering, which exploits the intersection between humans and technology to trick users into executing malicious code on behalf of the attacker.

  • While this technique has been around since 2024, Darktrace observed campaign activity in the first half of 2025 suggesting a resurgence.  
  • A range of threat actors – from APTs to MaaS and RaaS have adopted this technique to deliver secondary payloads, like information stealing malware.
  • Attackers use fraudulent or compromised legitimate websites to inject malicious plugins that masquerade as fake CAPTCHAs.
  • Targeted users believe they are completing human verification or resolving a website issue, unaware that they are being guided through a series of simple steps to execute PowerShell code on their system.
  • Darktrace observed campaign activity during the first half of 2025 across a range of sectors, including Government, Healthcare, Insurance, Retail and, Non-profit.

Not just AI: Automation is enabling Ransomware and SaaS exploitation

The rise of phishing kits like FlowerStorm and Mamba2FA, which enable phishing and abuse users’ trust by mimicking legitimate services to bypass multi-factor authentication (MFA), highlight how the barriers to entry for sophisticated attacks continue to fall, enabling new threat actors. Combined with Software-as-a-Service (SaaS) account compromise, these techniques make up a substantial portion of cybercriminal activity observed by Darktrace so far this year.

Credentials remain the weak link

A key theme across multiple cases of ransomware was threat actors abusing compromised credentials to gain initial entry into networks via:

  • Unauthorized access to internet-facing technology such as RDP servers and virtual private networks (VPNs).
  • Unauthorized access to SaaS accounts.

SaaS targeted ransomware is on the rise

The encryption of files within SaaS environments observed by Darktrace demonstrates a continued trend of ransomware actors targeting these platforms over traditional networks, potentially driven by a higher return on investment.

SaaS accounts are often less protected than traditional systems because of Single Sign-On (SSO).  Additionally, platforms like Salesforce often host sensitive data, including emails, financial records, customer information, and network configuration details. This stresses the need for robust identity management practices and continuous monitoring.

RaaS is adding complexity and speed to cyber attacks

RaaS has dominated the attack landscape, with groups like Qilin, RansomHub, and Lynx all appearing multiple times in cases across Darktrace’s customer base over the past six months. Detecting ransomware attacks before the encryption stage remains a significant challenge, particularly in RaaS operations where different affiliates often use varying techniques for initial entry and earlier stages of the attack. Darktrace’s recent analysis of Scattered Spider underscores the challenge of hardening defenses against such varying techniques.

CVE exploitation continues despite available patches

Darktrace has also observed ransomware gangs exploiting known Common Vulnerabilities and Exposures (CVEs), including the Medusa ransomware group’s use of the SimpleHelp vulnerabilities: CVE-2024-57727 and CVE-2024-57728 in March, despite patches being made available in January [2].

Misused tools + delayed patches = growing cyber risk

The exploitation of common remote management tools like SimpleHelp highlights the serious challenges defenders face when patch management cycles are suboptimal. As threat actors continue to abuse legitimate services for malicious purposes, the challenges facing defenders will only grow more complex.

Edge exploitation

It comes as no surprise that exploitation of internet-facing devices continued to feature prominently in Darktrace’s Threat Research investigations during the first half of 2025.

Observed CVE exploitation included:

Many of Darktrace’s observations of CVE exploitation so far in 2025 align with wider industry reporting, which suggests that Chinese-nexus threat actors were deemed to likely have exploited these technologies prior to public disclosure. In the case of CVE-2025-0994 - a vulnerability affecting Trimble Cityworks, an asset management system designed for use by local governments, utilities, airports, and public work agencies [3] - Darktrace observed signs of exploitation as early as January 19, well before vulnerability’s public disclosure on February 6 [4]. Darktrace’s early identification of the exploitation stemmed from the detection of a suspicious file download from 192.210.239[.]172:3219/z44.exe - later linked to Chinese-speaking threat actors in a campaign targeting the US government [5].

This case demonstrates the risks posed by the exploitation of internet-facing devices, not only those hosting more common technologies, but also software associated specifically tied to Critical National Infrastructure (CNI); a lucrative target for threat actors. This also highlights Darktrace’s ability to detect exploitation of internet-facing systems, even without a publicly disclosed CVE. Further examples of how Darktrace’s anomaly detection can uncover malicious activity ahead of public vulnerability disclosures can be found here.

New threats and returning adversaries

In the first half of 2025, Darktrace observed a wide range of threats, from sophisticated techniques employed by APT groups to large-scale campaigns involving phishing and information stealers.

BlindEagle (APT-C-36)

Among the observed APT activity, BlindEagle (APT-C-36) was seen targeting customers in Latin America (LATM), first identified in February, with additional cases seen as recently as June.

Darktrace also observed a customer targeted in a China-linked campaign involving the LapDogs ORB network, with activity spanning from December 2024 and June 2025. These likely nation-state attacks illustrate the continued adoption of cyber and AI capabilities into the national security goals of certain countries.

Sophisticated malware functionality

Further sophistication has been observed within specific malware functionality - such as the malicious backdoor Auto-Color, which has now been found to employ suppression tactics to cover its tracks if it is unable to complete its kill chain - highlighting the potential for advanced techniques across every layer of an attack.

Familiar foes

Alongside new and emerging threats, previously observed and less sophisticated tools, such as worms, Remote Access Trojans (RATs), and information stealers, continue to impact Darktrace customers.

The Raspberry Robin worm... First seen in 2021, has been repeatedly identified within Darktrace’s customer base since 2022. Most recently, Darktrace’s Threat Research team identified cases in April and May this year. Recent open-source intelligence (OSINT) reporting suggests that Raspberry Robin continues to evolve its role as an Initial Access Broker (IAB), paving the way for various attacks and remaining a concern [6].

RATs also remain a threat, with examples like AsyncRAT and Gh0st RAT impacting Darktrace customers.

In April multiple cases of MaaS were observed in Darktrace’s customer base, with information stealers Amadey and Stealc, as well as GhostSocks being distributed as a follow up payload after an initial Amadey infection.

Conclusion

As cyber threats evolve, attackers are increasingly harnessing AI to craft highly convincing email attacks, automating phishing campaigns at unprecedented scale and speed. This, coupled with rapid exploitation of vulnerabilities and the growing sophistication of ransomware gangs operating as organized crime syndicates, makes today’s threat landscape more dynamic and dangerous than ever. Cyber defenders collaborate to combat these threats – the coordinated takedown of Lumma Stealer in May was a notable win for both industry and law-enforcement [7], however OSINT suggests that this threat persists [8], and new threats will continue to arise.

Traditional security tools that rely on static rules or signature-based detection often struggle to keep pace with these fast-moving, adaptive threats. In this environment, anomaly-based detection tools are no longer optional—they are essential. By identifying deviations in normal user and system behavior, tools like Darktrace provide a proactive layer of defense capable of detecting novel and emerging threats, even those that bypass conventional security measures. Investing in anomaly-based detection is critical to staying ahead of attackers who now operate with automation, intelligence, and global coordination.

Credit to Emma Foulger (Global Threat Research Operations Lead), Nathaniel Jones (VP, Security & AI Strategy, Field CISO),  Eugene Chua (Principal Cyber Analyst & Analyst Team Lead), Nahisha Nobregas (Senior Cyber Analyst), Nicole Wong (Principal Cyber Analyst), Justin Torres (Senior Cyber Analyst), Matthew John (Director of Operations, SOC), Sam Lister (Specialist Security Researcher), Ryan Traill (Analyst Content Lead) and the Darktrace Incident Management team.

The information contained in this blog post is provided for general informational purposes only and represents the views and analysis of Darktrace as of the date of publication. While efforts have been made to ensure the accuracy and timeliness of the information, the cybersecurity landscape is dynamic, and new threats or vulnerabilities may have emerged since this report was compiled.

This content is provided “as is” and without warranties of any kind, either express or implied. Darktrace makes no representations or warranties regarding the completeness, accuracy, reliability, or suitability of the information, and expressly disclaims all warranties.

Nothing in this blog post should be interpreted as legal, technical, or professional advice. Users of this information assume full responsibility for any actions taken based on its content, and Darktrace shall not be liable for any loss or damage resulting from reliance on this material. Reference to any specific products, companies, or services does not constitute or imply endorsement, recommendation, or affiliation.

Appendices

Indicators of Compromise (IoCs)

IoC - Type - Description + Probability

LapDogs ORB network, December 2024-June 2025

www.northumbra[.]com – Hostname – Command and Control (C2) server

103.131.189[.]2 – IP Address - C2 server, observed December 2024 & June 2025

103.106.230[.]31 – IP Address - C2 server, observed December 2024

154.223.20[.]56 – IP Address – Possible C2 server, observed December 2024

38.60.214[.]23 – IP Address – Possible C2 server, observed January & February 2025

154.223.20[.]58:1346/systemd-log – URL – Possible ShortLeash payload, observed December 2024

CN=ROOT,OU=Police department,O=LAPD,L=LA,ST=California,C=US - TLS certificate details for C2 server

CVE-2025-0994, Trimble Cityworks exploitation, January 2025

192.210.239[.]172:3219/z44.exe – URL - Likely malicious file download

AsyncRAT, February-March 2025

windows-cam.casacam[.]net – Hostname – Likely C2 server

88.209.248[.]141 – IP Address – Likely C2 server

207.231.105[.]51 – IP Address – Likely C2 server

163.172.125[.]253 – IP Address – Likely C2 server

microsoft-download.ddnsfree[.]com – Hostname – Likely C2 server

95.217.34[.]113 – IP Address – Likely C2 server

vpnl[.]net – Hostname – Likely C2 server

157.20.182[.]16 – IP Address - Likely C2 server

185.81.157[.]19 – IP Address – Likely C2 server

dynamic.serveftp[.]net – IP Address – Likely C2 server

158.220.96.15 – IP Address – Likely C2 server

CVE-2024-57727 & CVE-2024-57728, SimpleHelp RMM exploitation, March 2025

213.183.63[.]41 – IP Address - C2 server

213.183.63[.]41/access/JWrapper-Windows64JRE-version.txt?time=3512082867 – URL - C2 server

213.183.63[.]41/access/JWrapper-Windows64JRE-00000000002-archive.p2.l2 – URL - C2 server

pruebas.pintacuario[.]mx – Hostname – Possible C2 server

144.217.181[.]205 – IP Address – Likely C2 server

erp.ranasons[.]com – Hostname – Possible destination for exfiltration

143.110.243[.]154 – IP Address – Likely destination for exfiltration

Blind Eagle, April-June 2025

sostenermio2024.duckdns[.]org/31agosto.vbs – URL – Possible malicious file download

Stealc, April 2025

88.214.48[.]93/ea2cb15d61cc476f[.]php – URL – C2 server

Amadey & GhostSocks, April 2025

195.82.147[.]98 – IP Address - Amadey C2 server

195.82.147[.]98/0Bdh3sQpbD/index.php – IP Address – Likely Amadey C2 activity

194.28.226.181 – IP Address – Likely GhostSocks C2 server

RaspberryRobin, May 2025

4j[.]pm – Hostname – C2 server

4xq[.]nl – Hostname – C2 server

8t[.]wf – Hostname – C2 server

Gh0stRAT, May 2025

lu.dssiss[.]icu  - Hostname – Likely C2 server

192.238.133[.]162:7744/1-111.exe – URL – Possible addition payload

8e9dec3b028f2406a8c546a9e9ea3d50609c36bb - SHA1 - Possible additional payload

f891c920f81bab4efbaaa1f7a850d484 - MD5 – Possible additional payload

192.238.133[.]162:7744/c3p.exe – URL - Possible additional payload

03287a15bfd67ff8c3340c0bae425ecaa37a929f - SHA1 - Possible additional payload

02aa02aee2a6bd93a4a8f4941a0e6310 - MD5 - Possible additional payload

192.238.133[.]162:7744/1-1111.exe – URL - Possible additional payload

1473292e1405882b394de5a5857f0b6fa3858fd1 - SHA1 - Possible additional payload

69549862b2d357e1de5bab899ec0c817 - MD5 - Possible additional payload

192.238.133[.]162:7744/1-25.exe – URL -  Possible additional payload

20189164c4cd5cac7eb76ba31d0bd8936761d7a7  - SHA1 - Possible additional payload

f42aa5e68b28a3f335f5ea8b6c60cb57 – MD5 - Possible additional payload

192.238.133[.]162:7744/Project1_se.exe – URL - Possible additional payload

fea1e30dfafbe9fa9abbbdefbcbe245b6b0628ad - SHA1 - Possible additional payload

5ea622c630ef2fd677868cbe8523a3d5 - MD5 - Possible additional payload

192.238.133[.]162:7744/Project1_se.exe - URL - Possible additional payload

aa5a5d2bd610ccf23e58bcb17d6856d7566d71b9  - SHA1 - Possible additional payload

9d33029eaeac1c2d05cf47eebb93a1d0 - MD5 - Possible additional payload

References and further reading

1.        https://cip.gov.ua/en/news/art28-atakuye-sektor-bezpeki-ta-oboroni-za-dopomogoyu-programnogo-zasobu-sho-vikoristovuye-shtuchnii-intelekt?utm_medium=email&_hsmi=113619842&utm_content=113619842&utm_source=hs_email

2.        https://www.s-rminform.com/latest-thinking/cyber-threat-advisory-medusa-and-the-simplehelp-vulnerability

3.        https://assetlifecycle.trimble.com/en/products/software/cityworks

4.     https://nvd.nist.gov/vuln/detail/CVE-2025-0994

5.     https://blog.talosintelligence.com/uat-6382-exploits-cityworks-vulnerability/

6.        https://www.silentpush.com/blog/raspberry-robin/

7.        https://blogs.microsoft.com/on-the-issues/2025/05/21/microsoft-leads-global-action-against-favored-cybercrime-tool/

8.     https://www.trendmicro.com/en_sg/research/25/g/lumma-stealer-returns.html

Related Darktrace investigations

-              ClickFix

-              FlowerStorm

-              Mamba 2FA

-              Qilin Ransomware

-              RansomHub Ransomware

-              RansomHub Revisited

-              Lynx Ransomware

-              Scattered Spider

-              Medusa Ransomware

-              Legitimate Services Malicious Intentions

-              CVE-2025-0282 and CVE-2025-0283 – Ivanti CS, PS and ZTA

-              CVE-2025-31324 – SAP Netweaver

-              Pre-CVE Threat Detection

-              BlindEagle (APT-C-36)

-              Raspberry Robin Worm

-              AsyncRAT

-              Amadey

-              Lumma Stealer

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
Emma Foulger
Global Threat Research Operations Lead

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August 21, 2025

From VPS to Phishing: How Darktrace Uncovered SaaS Hijacks through Virtual Infrastructure Abuse

VPS phishingDefault blog imageDefault blog image

What is a VPS and how are they abused?

A Virtual Private Server (VPS) is a virtualized server that provides dedicated resources and control to users on a shared physical device.  VPS providers, long used by developers and businesses, are increasingly misused by threat actors to launch stealthy, scalable attacks. While not a novel tactic, VPS abuse is has seen an increase in Software-as-a-Service (SaaS)-targeted campaigns as it enables attackers to bypass geolocation-based defenses by mimicking local traffic, evade IP reputation checks with clean, newly provisioned infrastructure, and blend into legitimate behavior [3].

VPS providers like Hyonix and Host Universal offer rapid setup and minimal open-source intelligence (OSINT) footprint, making detection difficult [1][2]. These services are not only fast to deploy but also affordable, making them attractive to attackers seeking anonymous, low-cost infrastructure for scalable campaigns. Such attacks tend to be targeted and persistent, often timed to coincide with legitimate user activity, a tactic that renders traditional security tools largely ineffective.

Darktrace’s investigation into Hyonix VPS abuse

In May 2025, Darktrace’s Threat Research team investigated a series of incidents across its customer base involving VPS-associated infrastructure. The investigation began with a fleet-wide review of alerts linked to Hyonix (ASN AS931), revealing a noticeable spike in anomalous behavior from this ASN in March 2025. The alerts included brute-force attempts, anomalous logins, and phishing campaign-related inbox rule creation.

Darktrace identified suspicious activity across multiple customer environments around this time, but two networks stood out. In one instance, two internal devices exhibited mirrored patterns of compromise, including logins from rare endpoints, manipulation of inbox rules, and the deletion of emails likely used in phishing attacks. Darktrace traced the activity back to IP addresses associated with Hyonix, suggesting a deliberate use of VPS infrastructure to facilitate the attack.

On the second customer network, the attack was marked by coordinated logins from rare IPs linked to multiple VPS providers, including Hyonix. This was followed by the creation of inbox rules with obfuscated names and attempts to modify account recovery settings, indicating a broader campaign that leveraged shared infrastructure and techniques.

Darktrace’s Autonomous Response capability was not enabled in either customer environment during these attacks. As a result, no automated containment actions were triggered, allowing the attack to escalate without interruption. Had Autonomous Response been active, Darktrace would have automatically blocked connections from the unusual VPS endpoints upon detection, effectively halting the compromise in its early stages.

Case 1

Timeline of activity for Case 1 - Unusual VPS logins and deletion of phishing emails.
Figure 1: Timeline of activity for Case 1 - Unusual VPS logins and deletion of phishing emails.

Initial Intrusion

On May 19, 2025, Darktrace observed two internal devices on one customer environment initiating logins from rare external IPs associated with VPS providers, namely Hyonix and Host Universal (via Proton VPN). Darktrace recognized that these logins had occurred within minutes of legitimate user activity from distant geolocations, indicating improbable travel and reinforcing the likelihood of session hijacking. This triggered Darktrace / IDENTITY model “Login From Rare Endpoint While User Is Active”, which highlights potential credential misuse when simultaneous logins occur from both familiar and rare sources.  

Shortly after these logins, Darktrace observed the threat actor deleting emails referring to invoice documents from the user’s “Sent Items” folder, suggesting an attempt to hide phishing emails that had been sent from the now-compromised account. Though not directly observed, initial access in this case was likely achieved through a similar phishing or account hijacking method.

 Darktrace / IDENTITY model "Login From Rare Endpoint While User Is Active", which detects simultaneous logins from both a common and a rare source to highlight potential credential misuse.
Figure 2: Darktrace / IDENTITY model "Login From Rare Endpoint While User Is Active", which detects simultaneous logins from both a common and a rare source to highlight potential credential misuse.

Case 2

Timeline of activity for Case 2 – Coordinated inbox rule creation and outbound phishing campaign.
Figure 3: Timeline of activity for Case 2 – Coordinated inbox rule creation and outbound phishing campaign.

In the second customer environment, Darktrace observed similar login activity originating from Hyonix, as well as other VPS providers like Mevspace and Hivelocity. Multiple users logged in from rare endpoints, with Multi-Factor Authentication (MFA) satisfied via token claims, further indicating session hijacking.

Establishing control and maintaining persistence

Following the initial access, Darktrace observed a series of suspicious SaaS activities, including the creation of new email rules. These rules were given minimal or obfuscated names, a tactic often used by attackers to avoid drawing attention during casual mailbox reviews by the SaaS account owner or automated audits. By keeping rule names vague or generic, attackers reduce the likelihood of detection while quietly redirecting or deleting incoming emails to maintain access and conceal their activity.

One of the newly created inbox rules targeted emails with subject lines referencing a document shared by a VIP at the customer’s organization. These emails would be automatically deleted, suggesting an attempt to conceal malicious mailbox activity from legitimate users.

Mirrored activity across environments

While no direct lateral movement was observed, mirrored activity across multiple user devices suggested a coordinated campaign. Notably, three users had near identical similar inbox rules created, while another user had a different rule related to fake invoices, reinforcing the likelihood of a shared infrastructure and technique set.

Privilege escalation and broader impact

On one account, Darktrace observed “User registered security info” activity was shortly after anomalous logins, indicating attempts to modify account recovery settings. On another, the user reset passwords or updated security information from rare external IPs. In both cases, the attacker’s actions—including creating inbox rules, deleting emails, and maintaining login persistence—suggested an intent to remain undetected while potentially setting the stage for data exfiltration or spam distribution.

On a separate account, outbound spam was observed, featuring generic finance-related subject lines such as 'INV#. EMITTANCE-1'. At the network level, Darktrace / NETWORK detected DNS requests from a device to a suspicious domain, which began prior the observed email compromise. The domain showed signs of domain fluxing, a tactic involving frequent changes in IP resolution, commonly used by threat actors to maintain resilient infrastructure and evade static blocklists. Around the same time, Darktrace detected another device writing a file named 'SplashtopStreamer.exe', associated with the remote access tool Splashtop, to a domain controller. While typically used in IT support scenarios, its presence here may suggest that the attacker leveraged it to establish persistent remote access or facilitate lateral movement within the customer’s network.

Conclusion

This investigation highlights the growing abuse of VPS infrastructure in SaaS compromise campaigns. Threat actors are increasingly leveraging these affordable and anonymous hosting services to hijack accounts, launch phishing attacks, and manipulate mailbox configurations, often bypassing traditional security controls.

Despite the stealthy nature of this campaign, Darktrace detected the malicious activity early in the kill chain through its Self-Learning AI. By continuously learning what is normal for each user and device, Darktrace surfaced subtle anomalies, such as rare login sources, inbox rule manipulation, and concurrent session activity, that likely evade traditional static, rule-based systems.

As attackers continue to exploit trusted infrastructure and mimic legitimate user behavior, organizations should adopt behavioral-based detection and response strategies. Proactively monitoring for indicators such as improbable travel, unusual login sources, and mailbox rule changes, and responding swiftly with autonomous actions, is critical to staying ahead of evolving threats.

Credit to Rajendra Rushanth (Cyber Analyst), Jen Beckett (Cyber Analyst) and Ryan Traill (Analyst Content Lead)

References

·      1: https://cybersecuritynews.com/threat-actors-leveraging-vps-hosting-providers/

·      2: https://threatfox.abuse.ch/asn/931/

·      3: https://www.cyfirma.com/research/vps-exploitation-by-threat-actors/

Appendices

Darktrace Model Detections

•   SaaS / Compromise / Unusual Login, Sent Mail, Deleted Sent

•   SaaS / Compromise / Suspicious Login and Mass Email Deletes

•   SaaS / Resource / Mass Email Deletes from Rare Location

•   SaaS / Compromise / Unusual Login and New Email Rule

•   SaaS / Compliance / Anomalous New Email Rule

•   SaaS / Resource / Possible Email Spam Activity

•   SaaS / Unusual Activity / Multiple Unusual SaaS Activities

•   SaaS / Unusual Activity / Multiple Unusual External Sources For SaaS Credential

•   SaaS / Access / Unusual External Source for SaaS Credential Use

•   SaaS / Compromise / High Priority Login From Rare Endpoint

•   SaaS / Compromise / Login From Rare Endpoint While User Is Active

List of Indicators of Compromise (IoCs)

Format: IoC – Type – Description

•   38.240.42[.]160 – IP – Associated with Hyonix ASN (AS931)

•   103.75.11[.]134 – IP – Associated with Host Universal / Proton VPN

•   162.241.121[.]156 – IP – Rare IP associated with phishing

•   194.49.68[.]244 – IP – Associated with Hyonix ASN

•   193.32.248[.]242 – IP – Used in suspicious login activity / Mullvad VPN

•   50.229.155[.]2 – IP – Rare login IP / AS 7922 ( COMCAST-7922 )

•   104.168.194[.]248 – IP – Rare login IP / AS 54290 ( HOSTWINDS )

•   38.255.57[.]212 – IP – Hyonix IP used during MFA activity

•   103.131.131[.]44 – IP – Hyonix IP used in login and MFA activity

•   178.173.244[.]27 – IP – Hyonix IP

•   91.223.3[.]147 – IP – Mevspace Poland, used in multiple logins

•   2a02:748:4000:18:0:1:170b[:]2524 – IPv6 – Hivelocity VPS, used in multiple logins and MFA activity

•   51.36.233[.]224 – IP – Saudi ASN, used in suspicious login

•   103.211.53[.]84 – IP – Excitel Broadband India, used in security info update

MITRE ATT&CK Mapping

Tactic – Technique – Sub-Technique

•   Initial Access – T1566 – Phishing

                       T1566.001 – Spearphishing Attachment

•   Execution – T1078 – Valid Accounts

•   Persistence – T1098 – Account Manipulation

                       T1098.002 – Exchange Email Rules

•   Command and Control – T1071 – Application Layer Protocol

                       T1071.001 – Web Protocols

•   Defense Evasion – T1036 – Masquerading

•   Defense Evasion – T1562 – Impair Defenses

                       T1562.001 – Disable or Modify Tools

•   Credential Access – T1556 – Modify Authentication Process

                       T1556.004 – MFA Bypass

•   Discovery – T1087 – Account Discovery

•      Impact – T1531 – Account Access Removal

The content provided in this blog is published by Darktrace for general informational purposes only and reflects our understanding of cybersecurity topics, trends, incidents, and developments at the time of publication. While we strive to ensure accuracy and relevance, the information is provided “as is” without any representations or warranties, express or implied. Darktrace makes no guarantees regarding the completeness, accuracy, reliability, or timeliness of any information presented and expressly disclaims all warranties.

Nothing in this blog constitutes legal, technical, or professional advice, and readers should consult qualified professionals before acting on any information contained herein. Any references to third-party organizations, technologies, threat actors, or incidents are for informational purposes only and do not imply affiliation, endorsement, or recommendation.

Darktrace, its affiliates, employees, or agents shall not be held liable for any loss, damage, or harm arising from the use of or reliance on the information in this blog.

The cybersecurity landscape evolves rapidly, and blog content may become outdated or superseded. We reserve the right to update, modify, or remove any content without notice.

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Rajendra Rushanth
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August 15, 2025

From Exploit to Escalation: Tracking and Containing a Real-World Fortinet SSL-VPN Attack

Fortinet SSL-VPN AttackDefault blog imageDefault blog image

Threat actors exploiting Fortinet CVEs

Over the years, Fortinet has issued multiple alerts about a wave of sophisticated attacks targeting vulnerabilities in its SSL-VPN infrastructure. Despite the release of patches to address these vulnerabilities, threat actors have continued to exploit a trio of Common Vulnerabilities and Exposures (CVEs) disclosed between 2022 and 2024 to gain unauthorized access to FortiGate devices.

Which vulnerabilities are exploited?

The vulnerabilities—CVE-2022-42475, CVE-2023-27997, and CVE-2024-21762—affect Fortinet’s SSL-VPN services and have been actively exploited by threat actors to establish initial access into target networks.

The vulnerabilities affect core components of FortiOS, allowing attackers to execute remote code on affected systems.

CVE-2022-42475

Type: Heap-Based Buffer Overflow in FortiOS SSL-VPN

Impact: Remote Code Execution (Actively Exploited)

This earlier vulnerability also targets the SSL-VPN interface and has been actively exploited in the wild. It allows attackers to execute arbitrary code remotely by overflowing a buffer in memory, often used to deploy malware or establish persistent backdoors [6].

CVE-2023-27997

Type: Heap-Based Buffer Overflow in FortiOS and FortiProxy

Impact: Remote Code Execution

This flaw exists in the SSL-VPN component of both FortiOS and FortiProxy. By exploiting a buffer overflow in the heap memory, attackers can execute malicious code remotely. This vulnerability is particularly dangerous because it can be triggered without authentication, making it ideal for an initial compromise [5].

CVE-2024-21762

Type: Out-of-Bounds Write in sslvpnd

Impact: Remote Code Execution

This vulnerability affects the SSL-VPN daemon (sslvpnd) in FortiOS. It allows unauthenticated remote attackers to send specially crafted HTTP requests that write data outside of allocated memory bounds. This can lead to arbitrary code execution, giving attackers full control over a device [4].

In short, these flaws enable remote attackers to execute arbitrary code without authentication by exploiting memory corruption issues such as buffer overflows and out-of-bounds writes. Once inside, threat actors use symbolic link (symlink) in order to maintain persistence on target devices across patches and firmware updates. This persistence then enables them to bypass security controls and manipulate firewall configurations, effectively turning patched systems into long-term footholds for deeper network compromise [1][2][3].

Darktrace’s Coverage

Darktrace detected a series of suspicious activities originating from a compromised Fortinet VPN device, including anomalous HTTP traffic, internal network scanning, and SMB reconnaissance, all indicative of post-exploitation behavior. Following initial detection by Darktrace’s real-time models, its Autonomous Response capability swiftly acted on the malicious activity, blocking suspicious connections and containing the threat before further compromise could occur.

Further investigation by Darktrace’s Threat Research team uncovered a stealthy and persistent attack that leveraged known Fortinet SSL-VPN vulnerabilities to facilitate lateral movement and privilege escalation within the network.

Phase 1: Initial Compromise – Fortinet VPN Exploitation

The attack on a Darktrace customer likely began on April 11 with the exploitation of a Fortinet VPN device running an outdated version of FortiOS. Darktrace observed a high volume of HTTP traffic originating from this device, specifically targeting internal systems. Notably, many of these requests were directed at the /cgi-bin/ directory,  a common target for attackers attempting to exploit web interfaces to run unauthorized scripts or commands. This pattern strongly indicated remote code execution attempts via the SSL-VPN interface [7].

Once access was gained, the threat actor likely modified existing firewall rules, a tactic often used to disable security controls or create hidden backdoors for future access. While Darktrace does not have direct visibility into firewall configuration changes, the surrounding activity and post-exploitation behavior indicated that such modifications were made to support long-term persistence within the network.

HTTP activity from the compromised Fortinet device, including repeated requests to /cgi-bin/ over port 8080.
Figure 1: HTTP activity from the compromised Fortinet device, including repeated requests to /cgi-bin/ over port 8080

Phase 2: Establishing Persistence & Lateral Movement

Shortly after the initial compromise of the Fortinet VPN device, the threat actor began to expand their foothold within the internal network. Darktrace detected initial signs of network scanning from this device, including the use of Nmap to probe the internal environment, likely in an attempt to identify accessible services and vulnerable systems.

Darktrace’s detection of unusual network scanning activities on the affected device.
Figure 2: Darktrace’s detection of unusual network scanning activities on the affected device.

Around the same time, Darktrace began detecting anomalous activity on a second device, specifically an internal firewall interface device. This suggested that the attacker had established a secondary foothold and was leveraging it to conduct deeper reconnaissance and move laterally through the network.

In an effort to maintain persistence within the network, the attackers likely deployed symbolic links in the SSL-VPN language file directory on the Fortinet device. While Darktrace did not directly observe symbolic link abuse, Fortinet has identified this as a known persistence technique in similar attacks [2][3]. Based on the observed post-exploitation behavior and likely firewall modifications, it is plausible that such methods were used here.

Phase 3: Internal Reconnaissance & Credential Abuse

With lateral movement initiated from the internal firewall interface device, the threat actor proceeded to escalate their efforts to map the internal network and identify opportunities for privilege escalation.

Darktrace observed a successful NTLM authentication from the internal firewall interface to the domain controller over the outdated protocol SMBv1, using the account ‘anonymous’. This was immediately followed by a failed NTLM session connection using the hostname ‘nmap’, further indicating the use of Nmap for enumeration and brute-force attempts. Additional credential probes were also identified around the same time, including attempts using the credential ‘guest’.

Darktrace detection of a series of login attempts using various credentials, with a mix of successful and unsuccessful attempts.
Figure 3: Darktrace detection of a series of login attempts using various credentials, with a mix of successful and unsuccessful attempts.

The attacker then initiated DCE_RPC service enumeration, with over 300 requests to the Endpoint Mapper endpoint on the domain controller. This technique is commonly used to discover available services and their bindings, often as a precursor to privilege escalation or remote service manipulation.

Over the next few minutes, Darktrace detected more than 1,700 outbound connections from the internal firewall interface device to one of the customer’s subnets. These targeted common services such as FTP (port 21), SSH (22), Telnet (23), HTTP (80), and HTTPS (443). The threat actor also probed administrative and directory services, including ports 135, 137, 389, and 445, as well as remote access via RDP on port 3389.

Further signs of privilege escalation attempts were observed with the detection of over 300 Netlogon requests to the domain controller. Just over half of these connections were successful, indicating possible brute-force authentication attempts, credential testing, or the use of default or harvested credentials.

Netlogon and DCE-RPC activity from the affected device, showing repeated service bindings to epmapper and Netlogon, followed by successful and failed NetrServerAuthenticate3 attempts.
Figure 4: Netlogon and DCE-RPC activity from the affected device, showing repeated service bindings to epmapper and Netlogon, followed by successful and failed NetrServerAuthenticate3 attempts.

Phase 4: Privilege Escalation & Remote Access

A few minutes later, the attacker initiated an RDP session from the internal firewall interface device to an internal server. The session lasted over three hours, during which more than 1.5MB of data was uploaded and over 5MB was downloaded.

Notably, no RDP cookie was observed during this session, suggesting manual access, tool-less exploitation, or a deliberate attempt to evade detection. While RDP cookie entries were present on other occasions, none were linked to this specific session—reinforcing the likelihood of stealthy remote access.

Additionally, multiple entries during and after this session show SSL certificate validation failures on port 3389, indicating that the RDP connection may have been established using self-signed or invalid certificates, a common tactic in unauthorized or suspicious remote access scenarios.

Darktrace’s detection of an RDP session from the firewall interface device to the server, lasting over 3 hours.
Figure 5: Darktrace’s detection of an RDP session from the firewall interface device to the server, lasting over 3 hours.

Darktrace Autonomous Response

Throughout the course of this attack, Darktrace’s Autonomous Response capability was active on the customer’s network. This enabled Darktrace to autonomously intervene by blocking specific connections and ports associated with the suspicious activity, while also enforcing a pre-established “pattern of life” on affected devices to ensure they were able to continue their expected business activities while preventing any deviations from it. These actions were crucial in containing the threat and prevent further lateral movement from the compromised device.

Darktrace’s Autonomous Response targeted specific connections and restricted affected devices to their expected patterns of life.
Figure 6: Darktrace’s Autonomous Response targeted specific connections and restricted affected devices to their expected patterns of life.

Conclusion

This incident highlights the importance of important staying on top of patching and closely monitoring VPN infrastructure, especially for internet-facing systems like Fortinet devices. Despite available patches, attackers were still able to exploit known vulnerabilities to gain access, move laterally and maintain persistence within the customer’s network.

Attackers here demonstrated a high level of stealth and persistence. Not only did they gain access to the network and carry out network scans and lateral movement, but they also used techniques such as symbolic link abuse, credential probing, and RDP sessions without cookies to avoid detection.  Darktrace’s detection of the post-exploitation activity, combined with the swift action of its Autonomous Response technology, successfully blocked malicious connections and contained the attack before it could escalate

Credit to Priya Thapa (Cyber Analyst), Vivek Rajan (Cyber Analyst), and Ryan Traill (Analyst Content Lead)

Appendices

Real-time Detection Model Alerts

·      Device / Suspicious SMB Scanning Activity

·      Device / Anomalous Nmap Activity

·      Device / Network Scan

·      Device / RDP Scan

·      Device / ICMP Address Scan

Autonomous Response Model Alerts:  

·      Antigena / Network / Insider Threat / Antigena Network Scan Block

·       Antigena / Network / Significant Anomaly / Antigena Significant Anomaly from Client Block

MITRE ATT&CK Mapping

Initial Access – External Remote Services – T1133

Initial Access – Valid Accounts – T1078

Execution – Exploitation for Client Execution – T1203

Persistence – Account Manipulation – T1098

Persistence – Application Layer Protocol – T1071.001

Privilege Escalation – Exploitation for Privilege Escalation – T1068

Privilege Escalation – Valid Accounts – T1078

Defense Evasion – Masquerading – T1036

Credential Access – Brute Force – T1110

Discovery – Network Service Scanning – T1046

Discovery – Remote System Discovery – T1018

Lateral Movement – Remote Services – T1021

Lateral Movement – Software Deployment Tools – T1072

Collection – Data from Local System – T1005

Collection – Data Staging – T1074

Exfiltration – Exfiltration Over Alternative Protocol – T1048

References

[1]  https://www.tenable.com/blog/cve-2024-21762-critical-fortinet-fortios-out-of-bound-write-ssl-vpn-vulnerability

[2] https://thehackernews.com/2025/04/fortinet-warns-attackers-retain.html

[3] https://www.cisa.gov/news-events/alerts/2025/04/11/fortinet-releases-advisory-new-post-exploitation-technique-known-vulnerabilities

[4] https://www.fortiguard.com/psirt/FG-IR-24-015

[5] https://www.tenable.com/blog/cve-2023-27997-heap-based-buffer-overflow-in-fortinet-fortios-and-fortiproxy-ssl-vpn-xortigate

[6]  https://www.tenable.com/blog/cve-2022-42475-fortinet-patches-zero-day-in-fortios-ssl-vpns

[7] https://www.fortiguard.com/encyclopedia/ips/12475

The content provided in this blog is published by Darktrace for general informational purposes only and reflects our understanding of cybersecurity topics, trends, incidents, and developments at the time of publication. While we strive to ensure accuracy and relevance, the information is provided “as is” without any representations or warranties, express or implied. Darktrace makes no guarantees regarding the completeness, accuracy, reliability, or timeliness of any information presented and expressly disclaims all warranties.

Nothing in this blog constitutes legal, technical, or professional advice, and readers should consult qualified professionals before acting on any information contained herein. Any references to third-party organizations, technologies, threat actors, or incidents are for informational purposes only and do not imply affiliation, endorsement, or recommendation.

Darktrace, its affiliates, employees, or agents shall not be held liable for any loss, damage, or harm arising from the use of or reliance on the information in this blog.

The cybersecurity landscape evolves rapidly, and blog content may become outdated or superseded. We reserve the right to update, modify, or remove any content without notice.

Continue reading
About the author
Priya Thapa
Cyber Analyst
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