Hrozvné hrozby kybernetické bezpečnosti odhalené v březnu 2025

březen 2025 viděl významný vývoj taktiky kybernetické hrozby, s ransomwarovým skupinami přijímají nové techniky a rozšiřují své operace. Výzkumníci zabezpečení tento měsíc identifikovali několik hrozeb s vysokým dopadem, včetně posunu skupiny podnikové špionáže na ransomware, Nové nástroje EDR Evasion, Sofistikované útoky národního státu, a klamné phishingové kampaně zaměřené na podniky. This comprehensive analysis covers the most significant cybersecurity developments that security professionals and businesses should be aware of.

RedCurl Evolves: Corporate Espionage Group Launches First Ransomware Campaign with QWCrypt

On March 26, 2025, security researchers identified that the notorious hacking group RedCurl (also known as Earth Kapre and Red Wolf) has shifted from its traditional corporate espionage activities to deploying ransomware for the first time. This strategic pivot marks a significant evolution in the group’s tactics, techniques, and procedures (TTPs).

Technical Analysis of QWCrypt Ransomware

The newly identified ransomware strain, named QWCrypt, specifically targets virtual machines, making it particularly dangerous for organizations with virtualized infrastructure. The malware’s attack chain begins with sophisticated spear-phishing emails containing HR-themed lures. These emails deliver malicious PDFs and ISO files that sideload malware through a legitimate Adobe executable, exploiting trusted application paths to evade detection.

Attack Phase	Technické podrobnosti
Initial Access	Spear-phishing emails with HR-themed lures containing malicious PDFs and ISO files
Execution	Sideloading malware through legitimate Adobe executable
Vytrvalost	Registry modifications and scheduled tasks created with system privileges
Lateral Movement	Credential theft and exploitation of unpatched vulnerabilities
Dopad	Encryption of virtual machines, rendering entire infrastructures inoperable

The ransomware’s design appears to mimic elements from established groups like LockBit and HardBit, potentially to confuse attribution efforts. Zejména, researchers have not identified a dedicated leak site associated with these attacks, raising questions about whether the ransom demand is genuine or if the ransomware deployment serves as a distraction from the group’s traditional espionage activities.

Targets and Geographic Distribution

RedCurl has historically targeted organizations in Canada, Germany, Norway, the United Kingdom, and the United States. The group’s shift to ransomware operations potentially expands its threat profile from data theft to operational disruption across these regions.

EDRKillShifter: RansomHub’s Security Evasion Tool Links Multiple Cybercrime Groups

In a significant development tracked throughout March, security researchers have discovered connections between three separate cybercrime groups through their use of a common security evasion tool called EDRKillShifter. This tool, originally developed for affiliates of the RansomHub ransomware-as-a-service (RaaS) operation, exploits vulnerable drivers to disable endpoint detection and response (EDR) software.

Tool Capabilities and Technical Details

EDRKillShifter represents an advanced “bring your own vulnerable driver” (BYOVD) approach to disabling security defenses. The tool targets legitimate but vulnerable system drivers, exploiting them to shut down protective measures within the operating system. When deployed successfully, it effectively blinds security tools to subsequent malicious activities.

A newly identified threat actor, dubbed QuadSwitcher, has been observed using EDRKillShifter in attacks attributed to multiple ransomware groups, počítaje v to:

• RansomHub
• Play ransomware
• Medusa ransomware
• BianLian ransomware

Researchers confirmed the connection between these groups by analyzing shared EDRKillShifter samples and command-and-control server infrastructure, demonstrating how tooling is being shared across different ransomware operations.

Defense Recommendations

Since these attacks require administrative access, organizations can implement several preventive measures:

1. Implement driver blocklisting for known vulnerable drivers
2. Use Windows Defender’s driver blocklist feature for protection
3. Monitor for driver loading events, particularly those associated with third-party tools
4. Deploy advanced EDR solutions that can detect attempts to disable security software
5. Implement strong access controls to prevent attackers from gaining administrative privileges

The rise of EDR killers highlights a concerning trend in ransomware tactics, as threat actors continuously adapt to bypass increasingly sophisticated security defenses.

Chinese APT Group FamousSparrow Evolves Attack Toolkit with ShadowPad

Security researchers have identified targeted attacks against a U.S. trade group and a Mexican research institute attributed to the Chinese advanced persistent threat (APT) group FamousSparrow. The campaign, first detected in early March 2025, involves the deployment of the group’s signature SparrowDoor backdoor alongside ShadowPad malware – marking the first observed instance of FamousSparrow using this particular tool.

Technical Details of the Attack

Analysis of the campaign revealed two new versions of SparrowDoor, including a significantly enhanced modular variant with improved command execution capabilities. The attack sequence follows a familiar pattern for nation-state actors:

1. Initial Access: Exploitation of outdated Windows Server and Microsoft Exchange Server vulnerabilities
2. Vytrvalost: Deployment of a sophisticated web shell for maintaining access
3. Payload Delivery: Installation of SparrowDoor backdoor and ShadowPad malware

The modular version of SparrowDoor supports multiple advanced capabilities, počítaje v to:

• Keystroke logging for credential theft
• File transfer for data exfiltration
• Process manipulation to maintain stealth
• Remote desktop capture for visual intelligence gathering

ShadowPad, a modular backdoor commonly associated with Chinese state-sponsored threat actors, significantly expands FamousSparrow’s capabilities, suggesting potential collaboration or tool-sharing between Chinese APT groups.

FBI Warning: Fake File Converters Stealing Information and Deploying Ransomware

The FBI Denver field office has issued an urgent warning after observing an increase in reports of fake online document converters being used to steal sensitive information and deploy ransomware. This warning, issued on March 20, 2025, highlights a concerning trend targeting both personal and business users.

How the Attack Works

Cybercriminals create deceptive websites that claim to provide free document conversion services but conceal malicious intentions:

1. Users searching for document conversion tools encounter these sites, often promoted through Google ads
2. The sites appear legitimate and may actually provide the promised conversion functionality
3. When users upload documents for conversion, the sites extract sensitive information from the file contents
4. The returned converted files contain embedded malware that establishes remote access
5. In more severe cases, ransomware is deployed, encrypting the victim’s files

Researchers have identified multiple indicators that help identify these fraudulent converter sites:

Warning Sign	Podrobnosti
Domain Age	Typically registered within the past 30 dní
Zásady ochrany osobních údajů	Missing or extremely vague privacy information
Contact Information	No legitimate business contact details
SSL Certificate	Often using free certificates with minimal validation
Website Design	Clone of legitimate services with minor modifications

The malware delivered through these services can extract a wide range of sensitive information, including names, hesla, cryptocurrency seeds, and banking credentials, leading to significant financial losses for victims.

Preventing Fake Converter Attacks

To protect against these threats, the FBI recommends several preventative measures:

• Use only established, reputable file conversion tools and services
• Install comprehensive security software that can identify malicious websites
• Verify website legitimacy before uploading sensitive documents
• Consider using offline conversion tools when handling sensitive information
• Regularly back up critical files to enable recovery in case of ransomware attack

For businesses and individuals who have already fallen victim to these scams, a prompt malware removal process is essential to mitigate potential damage.

SEO Professionals Targeted by Sophisticated Phishing Campaign

A newly identified phishing campaign is specifically targeting SEO professionals using fake Semrush Google Ads designed to steal Google account credentials. Semrush, a popular SaaS platform providing tools for SEO, online advertising, and content marketing, is being impersonated in this highly targeted campaign.

Campaign Details and Objectives

Security analysts believe a Brazilian threat group is behind this campaign, which specifically aims to capture Google Ads accounts for launching further malvertising attacks. The operation demonstrates a sophisticated understanding of the digital marketing ecosystem:

1. Attackers create convincing phishing sites mimicking Semrush’s interface
2. These sites use domain names similar to Semrush but with different top-level domains
3. Victims are forced to authenticate via “Login with Google” funkčnost
4. When credentials are entered, attackers gain access to the victim’s Google account
5. This access enables the theft of sensitive business data from Google Analytics and Google Search Console

In a related development, another ongoing phishing campaign is leveraging fake DeepSeek ads in Google search results to deliver the Heracles MSIL Trojan, an information-stealing malware targeting cryptocurrency wallets. This campaign uses sponsored Google search results to direct victims to malicious websites that distribute the infostealer.

Industry Impact and Prevention

These phishing campaigns highlight the evolving nature of targeted attacks against specific professional groups. SEO and digital marketing professionals should implement additional security measures, počítaje v to:

• Enabling multi-factor authentication on all Google accounts
• Carefully verifying the URL of login pages before entering credentials
• Using password managers with phishing detection capabilities
• Being skeptical of Google Ads for software services, even when they appear at the top of search results
• Implementing company-wide security awareness training about these specific threats

Organizations should also consider implementing comprehensive security solutions that can detect and block phishing attempts and malware downloads automatically.

Coordinated Defense: Responding to the Evolving Threat Landscape

As these threats demonstrate, cybercriminal tactics continue to evolve in sophistication and impact. Organizations should adopt a multi-layered security approach that includes:

1. Vulnerability Management: Maintain an up-to-date inventory of systems and implement regular patching, particularly for internet-facing applications like Microsoft Exchange.
2. Email Security: Deploy advanced email filtering solutions to detect and block sophisticated phishing attempts, especially those using HR-themed lures.
3. EDR/XDR Solutions: Implement modern endpoint protection platforms that can detect and respond to attempts to disable security tools.
4. Security Awareness: Conduct regular training for employees, with special focus on recognizing phishing attempts and suspicious websites.
5. Incident Response Planning: Develop and regularly test incident response procedures to ensure rapid containment and recovery in the event of a security breach.

The convergence of ransomware operations, nation-state tactics, and targeted phishing campaigns creates a challenging security environment that requires vigilance and proactive defense measures. By staying informed about emerging threats and implementing appropriate security controls, organizations can reduce their risk exposure in this evolving landscape.

For individuals and businesses concerned about potential infections, consider using tools like Trojan Remover to scan for and eliminate malware that might have already compromised your systems.