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Active Exploitation of File Transfer Vulnerabilities

Cyber Threats

At Arete

Cybersecurity Trends

Threat actors are actively exploiting two critical vulnerabilities in CrushFTP and Gladinet’s CentreStack and Triofox products, leading to data exfiltration and extortion. CrushFTP, a managed file transfer solution, is vulnerable to an authentication bypass vulnerability designated CVE-2025-31161. The flaw is simple to exploit, and public exploit code is readily available, increasing risk for organizations that use the platform. Meanwhile, Gladinet’s CentreStack and Triofox products, both file-sharing and remote access platforms, are impacted by a critical remote code execution (RCE) vulnerability stemming from a hardcoded key in its configuration. This flaw (CVE-2025-30406) allows attackers to forge payloads and execute arbitrary code on the server.

What’s Notable and Unique

  • CVE-2025-31161 is a critical vulnerability affecting CrushFTP v10 and v11 and allows unauthenticated attackers to temporarily authenticate as any user, including administrators, leading to full server compromise. Over 1,500 vulnerable instances have been exposed, and as of April 10, 2025, approximately 440 organizations in North America remain vulnerable.

  • After exploiting the CrushFTP vulnerability, threat actors often install remote monitoring and management (RMM) tools like AnyDesk and MeshAgent before harvesting credentials. When certain threat actors exploit the vulnerability, they also install a Telegram bot to exfiltrate telemetry from infected hosts.

  • CVE-2025-30406 is a deserialization vulnerability in CentreStack and Triofox caused by the use of a hardcoded or weakly protected ‘machineKey’ in the IIS ‘web.config’ file, which secures ASP.NET ViewState data. If an attacker can obtain or predict this key, they can forge ViewState payloads that pass integrity checks and trigger deserialization, potentially resulting in remote code execution.

  • Upon successful exploitation, threat actors often deploy a malicious executable, install the MeshCentral remote access tool, and conduct lateral movement within the network. The vulnerable Triofox product is commonly used by managed service providers (MSPs), posing a serious threat to MSPs and their customers.

Analyst Comments

Overlaps in post-exploit techniques of CVE-2025-30406 (CentreStack and Triofox) and CVE-2025-31161 (CrushFTP), indicate potentially coordinated threat activity or shared attacker infrastructure. Threat actors have installed MeshCentral and used IP address 2.58.56[.]16 for post-exploitation communication in incidents after the exploit of both vulnerabilities. However, based on observed behavior and the ease of exploitation, multiple threat actors are likely exploiting these vulnerabilities. At least one threat actor, KillSec, has publicly claimed exploitation and exfiltration by leveraging the CrushFTP vulnerability. Arete has observed other threat actors extort victims after allegedly exploiting the CrushFTP vulnerability.
 
The CrushFTP vulnerability has been exploited since March 31, 2025, so any organizations using a vulnerable version of CrushFTP that have not updated should assess for potential unauthorized access and exfiltration. Organizations using a vulnerable version of CrushFTP can take two actions to remediate the vulnerability: upgrade to version 10.8.4 or version 11.3.1 or enable a DMZ proxy instance. Applying the patch will not remove the access of any threat actors who have already exploited the vulnerability and created a new valid user account for the application. For organizations affected by the CentreStack and Triofox vulnerability, an updated version was released by the company that resolves the vulnerability and generates a new machine key.

Sources

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Article

Ransomware Trends & Data Insights: July 2026

INC Ransom was the most active threat group in July, while activity remained relatively distributed among multiple threat groups, with 19 unique groups observed throughout the month. Alongside INC Ransom, Qilin, Global Secret Group, Anubis, and DragonForce rounded out the five most active threat groups observed in July. Several emerging threat actors were also observed during the month, including Booba Team, Settra, and Global Secret Group.

Figure 1. Activity from the top 3 threat groups in July 2026

 Throughout the month, analysts at Arete identified several trends behind the threat actors perpetrating cybercrime activities:

  • In July 2026, Global Secret Group emerged as a new threat actor, leveraging the leaked LockBit 3.0 (LockBit Black) source code. Although the group began operations in June 2026, it quickly accumulated a substantial number of victims on its data leak site (DLS). The group operates through TOR-based negotiation portals and qTox communications. Notably, its DLS provides step-by-step guidance on purchasing Bitcoin, including references to Coinbase and Binance, demonstrating a streamlined, victim-focused extortion process designed to simplify ransom payments.

  • Similar to Fulcrumsec, the recently emerged Settra ransomware group appears to leverage AI-driven analysis of stolen data, publishing detailed and highly structured victim reports on its DLS. Additionally, a potential EDR-disabling tool, edr_blind.exe, was identified in multiple cases, suggesting a focus on defense-evasion capabilities.

  • With the continuation of the FortiBleed campaign, researchers have now identified compromised FortiGate credentials being leveraged by both the INC and Lynx ransomware operations. Analysis revealed direct operational links between the groups, including shared ransomware infrastructure and overlap between FortiBleed victims and ransomware targets. The operators are also incorporating AI to enhance various stages of the attack lifecycle and increase operational efficiency and scale. Notably, Arete also observed an INC ransomware intrusion leveraging FortiBleed-derived access in July, reinforcing the campaign's role as a precursor to ransomware deployment.

Sources

  • Arete Internal

Podcast

Cyber Campfire: June Threat Trends & Insights

In this episode of Arete’s Cyber Campfire podcast, our Threat Intelligence Team discusses trends, statistics, and emerging threat actors from June 2026. Tune in for firsthand insights on today’s threat landscape that can enhance your approach to cyber risk.

Article

Current: Misconfigured Server Reveals Multiple Phishing Campaigns

Researchers uncovered three Microsoft 365 phishing campaigns after discovering a misconfigured HTTP server that exposed a threat actor’s phishing tools, configurations, victim logs, and operational infrastructure. The investigation revealed two operators using custom Evilginx-based adversary-in-the-middle (AiTM) phishing frameworks to steal authentication sessions and bypass MFA protections. A third operator abused Microsoft’s OAuth Device Code flow by tricking victims into completing authentication through Microsoft’s legitimate login process, allowing attackers to obtain valid access and refresh tokens without stealing passwords. The largest campaign compromised at least 218 victims across 12 countries, primarily targeting corporate Microsoft 365 accounts, with refresh tokens enabling persistent access. Researchers also identified the use of remote management tools for maintaining access, AI-assisted development of phishing tooling, and links to broader Phishing-as-a-Service (PhaaS) ecosystems, highlighting how commodity frameworks and automation are lowering the barrier for sophisticated identity-based attacks.

What’s Notable and Unique

  • The campaigns demonstrate the continued shift from traditional credential theft to identity- and token-based compromise, in which attackers target authentication sessions, cookies, and OAuth tokens rather than relying solely on password theft. By obtaining valid authentication artifacts, attackers can access Microsoft 365 environments while bypassing conventional MFA protections.


  • The use of Evilginx-based AiTM frameworks highlights how publicly available phishing tools have evolved into effective MFA-bypass platforms. These frameworks proxy legitimate login pages, capture authenticated sessions, and allow attackers to reuse valid sessions without requiring victims’ credentials again.


  • The OAuth Device Code flow abuse represents a different attack method, in which attackers leverage a legitimate Microsoft authentication mechanism to obtain tokens after victims approve the request. This approach bypasses password theft entirely by abusing trusted authentication workflows.


  • The exposed infrastructure provided insight into attacker operations, including phishing configurations, victim tracking data, remote administration tools, and evidence of AI-assisted development. The findings demonstrate how phishing ecosystems now provide reusable tooling and automation that reduce the technical expertise required to conduct large-scale identity attacks.

Analyst Comments

These Microsoft 365 phishing campaigns demonstrate the ongoing evolution of identity-focused attacks, as adversaries increasingly target authentication sessions, tokens, and legitimate cloud authorization mechanisms to bypass traditional security controls. The combination of AiTM phishing, OAuth abuse, remote management tools, and PhaaS infrastructure enables threat actors to maintain persistent access while blending into legitimate cloud activity.

The growing availability of phishing frameworks and AI-assisted attack development highlights the need for continuous identity security improvements beyond traditional phishing defenses. Arete recommends that organizations strengthen identity monitoring, adopt phishing-resistant MFA where possible, review OAuth application permissions, monitor token activity, and implement conditional access policies to detect and restrict suspicious Microsoft 365 authentication behavior. Security teams should also monitor post-compromise indicators such as abnormal mailbox access, suspicious application consent, unauthorized remote tools, and unusual sign-in activity.

Sources

  • One Misconfigured Server, Three Active Campaigns: Full exposure of three AiTM Phishing Operators

  • Misconfigured Server Reveals Three Evilginx Phishing Operations Targeting Microsoft 365

Podcast

Digital Forensics Meets the Courtroom: Insights on Expert Witness and Cyber-Related Litigation

In this episode of Bytes of Insight, host Vinny Sakore and special guest Dr. Bruce Hartley, Managing Director and Co-Founder of Advisory Services at Arete, discuss the evolving role of digital forensics and expert witness work in cybersecurity litigation. Tune in for firsthand insights on how Arete conducts post-breach investigations, what it takes to undergo cross-examination on the stand, and how emerging threats like AI-driven social engineering and third-party breaches are reshaping the advisory landscape.