Article
Microsoft Exchange Server Zero Day Hack Insight
Arete Analysis

On March 2, 2021, Microsoft disclosed and provided security updates for four [4] critical vulnerabilities — CVE-2021-26855, CVE-2021-26857, CVE-2021-26858, and CVE-2021-27065 — impacting on-premises Microsoft Exchange Servers.
While Internet-facing Exchange Servers, such as Outlook Web Access systems, are at particular risk — and especially those at organizations without a dedicated Exchange Server administrator — Microsoft says the vulnerabilities do not impact Office 365/Exchange online mailboxes.
The Microsoft Threat Intelligence Center (MSTIC) attributes the activity to HAFNIUM, a Chinese state-sponsored threat group. Chinese state-sponsored threat actors historically target government agencies, higher-education institutions, law firms, defense contractors, policy think tanks, non-governmental organizations (NGOs), and most recently, infectious disease researchers.
IMMEDIATE ACTION: If you have not done so already, review the Microsoft advisories and apply patches to protect vulnerable systems.

Arete Contextual Insights
State-sponsored threat groups, such as HAFNIUM, have the time, skills, and resources to manufacture these potent vulnerability exploits. They are not, however, the only bad actors wielding these techniques.
Beyond what Chinese state-sponsored operations have perpetrated, Arete expects broad impact in high orders of magnitude across multiple industry verticals.
Since the disclosure, multiple security researchers have been analyzing the Exchange
vulnerability patches. Arete can assert that cybercriminals and other state-sponsored actors are doing the same, most likely racing against patch cycles.The Cybersecurity and Infrastructure Security Agency (CISA) and other high-fidelity sources estimate that tens of thousands of organizations are likely compromised. Via research channels, Arete is aware that one high-fidelity source provided Information Sharing and Analysis Centers (ISACs) with a list of approximately 12,000 organizations for victim notification.
Leveraging Microsoft resources, Arete has identified multiple impacted clients and is currently responding to exploitations across a broad variety of organizations from a variety of cybercrime actors deploying payloads, including, but not limited to, cryptomining malware and ransomware.
Follow-On Actions
Assess systems to validate compromise and analyze impact. Rapid identification and triage
analysis through deployment of SentinelOne and data collection scripts across the impacted Exchange Server(s) to identify malicious activity.
Implement protective measures to harden environments. Based on findings, deploy SentinelOne throughout the remainder of the environment to identify all instances of lateral movement, search for indicators of compromise (IOC’s), and provide insight into the current state of systems health throughout the environment.
Additional Defense Services Available
Managed Detection and Response (MDR) service combines cutting-edge machine learning and artificial intelligence technologies with insights from Arete cyber professionals to provide 24/7 monitoring, reporting, and defense against threats.
Cyber Strategy and Defense. Arete performs current-state testing to assess clients’ cyber hygiene and create a prioritized action plan that closes identified security gaps, strengthens existing infrastructure, and formalizes people, processes, and technologies into a robust cybersecurity program.
Cloud Advisory and Architecture Services. Arete helps clients navigate the shared responsibility model, advising on cloud architectures based on economics, business use, and security.
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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
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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
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