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Black Kingdom Returns to Exploit Zero-Day Vulnerabilities in Unpatched Microsoft Exchange Servers

Arete Analysis

Summary

Black Kingdom ransomware recently resurfaced to target a zero-day vulnerability in Microsoft Exchange servers.

Earlier this month, Microsoft released a statement notifying the public of a zero-day exploit that affected its on-premises Exchange Servers, versions 2013 through 2019. Within a week, Arete incident responders spoke to approximately 100 affected companies — small- and medium-sized companies that had no reason to be on the target list of the Microsoft-coined hacking group Hafnium.

The worst part about this zero-day announcement was that sometime around March 10, the threat group published the proof-of-concept (PoC) code to GitHub. The irony: Microsoft owns GitHub; GitHub hosted the PoC code.  
 
Since that publication, the security community has been speculating on a second wave of attacks involving this exploit. A wave that would be worse than the first. A wave that would be linked to all sorts of corporate business interruptions from the likes of data exfiltration and ransomware.

How right was the speculation? Basically, the community #nailedit.

Second Wave of Ransomware Attacks Now Hitting

On March 12, DarkReading.com reported that a hacking group was deploying the ransomware variant,  DEARCRY!, which was affecting unpatched Microsoft Exchange Servers.  
 
Now, Arete has identified a second variant — Black Kingdom — that is also exploiting unpatched Microsoft Exchange Servers. The Black Kingdom variant made media headlines when it briefly surfaced and started to exploit the Pulse VPN zero-day in the early summer months of 2020. After, the group quietly disappeared … until this week. 

How the Black Kingdom Ransomware Group Operates

After the Black Kingdom group gains access to a network, they will perform some reconnaissance and start their encryption, leaving behind a fitting ransom note entitled decrypt_file.txt to announce their return.

Black Kingdom’s ransom note is one of the longest notes left behind by ransomware groups. It provides explicit instructions on how to contact them, the ransom amount, the Bitcoin wallet ID, and a message stating that they exfiltrated data from the network. The note also states that refusal to pay would lead them to publish the attack and stolen files on social media.

Steps you can take to help prevent unauthorized access to your network

The Microsoft Exchange vulnerability is widespread and, if like many other previously reported vulnerabilities, may not get patched automatically or quickly enough to prevent ransomware groups and any other malicious actors from gaining unauthorized access to your network.  
 
Follow these recommended steps protect your business and systems from unauthorized access: 

1. Immediately patch the Exchange Server. If the system is not or cannot be patched, disable Outlook for Web Access (OWA). If you cannot disable OWA, remove the Exchange Server from the internet.

  • Prior to running the tool, create a backup of the Exchange Server in its current state.

  • Microsoft released a One-Click Mitigation tool to patch, upgrade, and scan for malicious activity. You can find the tool on the company’s Security Center blog. 

  • Disable OWA according to the Microsoft guidelines. This may cause users to not have access to email.  

  • If you cannot patch or disable OWA, remove the system from the internet by disconnecting the network cable or powering the system down. This action will cause significant disruption and prevent users from receiving emails in certain configurations.  

 2. The U.S. Cybersecurity & Infrastructure Security Agency (CISA) issued a mitigation alert. Please read the article.

  • Block IP addresses at the firewall.

  • Enable geofencing if your organization does not conduct business outside of the United States.

3. Change passwords for all Windows-based user accounts.

  • Start with the most privileged domain administrator and service accounts, then work towards the least privileged user accounts. Also include the local administrator password.

4. Preserve any firewall, web application firewall, or VPN logs.

5. Deploy an Enterprise Detection and Response (EDR) tool throughout the environment to detect any unauthorized activity.

If you suspect any unauthorized access to your Microsoft Exchange Server or network, contact us.  

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Article

Europol Disrupts AudiA6 Crypto Laundering Service

European authorities have dismantled AudiA6, a major cryptocurrency laundering service linked to ransomware groups and broader cybercriminal networks. Between 2022 and 2025, the platform is believed to have processed over €336 million in illicit funds, enabling threat actors to obscure financial trails and monetize cybercrime proceeds. Its operators are also suspected of running Dark2Web, a dark web forum that facilitated collaboration, services, and connections among cybercriminals globally. This development underscores the expanding role of sophisticated, large-scale cryptocurrency laundering services in sustaining the cybercrime economy, enabling threat actors to obscure illicit funds and evade regulatory controls.

What’s Notable and Unique 

  • Following law enforcement disruption of Cryptex and Garantex, AudiA6 emerged as another platform involved in financial activities linked to ransomware groups. Investigators believe that AudiA6 became a central hub for cybercriminals seeking to launder stolen digital assets while obscuring the transaction trail from authorities.

  • On June 10, 2026, a coordinated operation resulted in two arrests in Georgia, the dismantling of key infrastructure (30+ servers, 25 domains), the freezing or seizure of over €778,000 in crypto, and the takedown of the AudiA6 and Dark2Web platforms. 

Analyst Comments

Ransomware groups and cybercriminal networks are increasingly leveraging sophisticated techniques, including chain-hopping, decentralized exchanges, and mixer-as-a-service platforms, to rapidly move illicit cryptocurrency across multiple blockchains, effectively obscuring transaction trails. Concurrently, the widespread use of fraudulent exchange accounts, mule wallets, and privacy-enhancing tools has elevated cryptocurrency laundering to a core enabler of the cybercrime ecosystem, allowing actors to bypass anti-money-laundering controls at scale. This investigation identified over 6,000 KYC records linked to money-mule accounts, many of which were tied to Russian-speaking intermediaries specifically recruited to facilitate the movement of illicit proceeds. These threat actors systematically used both commercial and domain-controlled email services to establish mule accounts across multiple cryptocurrency platforms. Collectively, these findings underscore the growing scale, coordination, and professionalization of cryptocurrency-enabled crime, highlighting the critical need for sustained, intelligence-led, and internationally coordinated efforts to disrupt these evolving financial ecosystems.

Sources

  • Ransomware gangs cut off from EUR 336 million ‘AudiA6’ crypto laundering pipeline

Article

Threat Actors Leverage AI for EDR Evasion

A threat actor has developed and deployed a ransomware attack toolkit enhanced with AI-assisted development workflows, enabling automated Active Directory (AD) discovery and improved EDR evasion capabilities. The toolkit leverages agent-based AI systems, such as Claude’s Opus and Cursor agents, for iterative malware development, testing, and refinement. 

What’s Notable and Unique 

  • Researchers have highlighted that this toolkit can not only generate ransomware code but also bypass sophisticated security defenses and identify AD networks for malware distribution. 

  • The framework incorporates multiple capabilities, including automated AD discovery and reconnaissance mechanisms, iterative EDR testing environments to refine evasion techniques, and a command-and-control (C2) infrastructure that leverages Telegram APIs and Cloudflare redirectors for stealth. 

  • Additionally, some agents were tasked with checking security research and technical posts for various bypass techniques. The agents recognized what was required for reproduction, extracted the techniques, mapped them to the MITRE ATT&CK knowledge base of adversary behaviors, set up a test lab, carried out the methodology, and reported the results. 

  • After a few repetitions, the modules seemed to avoid nearly all EDR solutions, despite the agent’s initial suggestion of a high failure rate. Although researchers found no evidence that AI was embedded in deployed malware or was operating independently in victim environments, the technology was still used to accelerate the iterative process of developing, testing, and refining payloads against security products, shortening the period between the publication of offensive security research and its practical implementation by threat actors. 

Analyst Comments 

AI-driven tools like this could accelerate the pace and sophistication of ransomware attacks, enabling even relatively inexperienced actors to launch high-impact campaigns. This development underscores the urgent need for security solutions to adapt to AI-assisted threats. Organizations must respond by strengthening detection engineering, improving visibility across environments, and maintaining robust security fundamentals.  

Sources 

  • AI-built ransomware toolkit automates EDR evasion, AD discovery  

  • Pointing a Cursor at evading detection

Article

Arete's 2026 Q1 Crimeware Report

Harness Arete’s unique data and expertise on extortion and ransomware to inform your response to the evolving threat landscape.

Article

CMS Vulnerability Leads to ClickFix Campaign

Threat actors compromised at least 700 education and technology websites in a recent ClickFix campaign by exploiting a critical SQL injection flaw (CVE-2026-26980) in the Ghost content management system (CMS). Adversaries combined the vulnerability with the ClickFix social engineering tactic to steal admin keys and inject a malicious JavaScript that delivers a fake Cloudflare or CAPTCHA verification pop-up, tricking victims into copying and pasting a malicious command into their systems.

What’s Notable and Unique

  • Rather than targeting the end user first, this campaign is unique in its initial exploitation of the system, followed by social engineering attempts. This hybrid attack style is likely being leveraged to bypass traditional defenses.

  • This recent campaign also highlights how trusted web properties can be weaponized at scale and coupled with unpatched CMS vulnerabilities. Rather than using the CMS compromise to perpetrate a single attack, threat actors turned it into a supply-chain attack that ultimately affected over 700 trusted websites.

Analyst Comments

As network defenders and their tools enhance threat detection capabilities, adversaries increasingly seek methods to bypass these defenses. By combining vulnerability exploitation, social engineering techniques, and staging for ancillary attacks, this campaign successfully bypassed traditional defenses and inflicted significant impact. Defending against hybrid cyberattacks requires comprehensive security controls beyond simply patching vulnerabilities. Organizations should focus on limiting movement within the environment, detecting abuse of trusted applications, and preventing end-user manipulation.

Sources

  • 700+ education and tech websites hijacked in huge ClickFix malware campaign

  • Under the engineering hood: Why Malwarebytes chose WordPress as its CMS

  • Think before you Click(Fix): Analyzing the ClickFix social engineering technique

  • Ghost CMS Vulnerability Exploited to Infect 700 Sites With ClickFix Malware