Hackers Exploited Windows WebDav Zero-Day to Drop Malware

Anatomy of a Sophisticated Attack Campaign

In early June 2025, cybersecurity experts identified a sophisticated campaign leveraging a critical Windows WebDav zero-day vulnerability, known as CVE-2025-33053. This vulnerability allowed attackers to exploit the Windows Web Distributed Authoring and Versioning (WebDav) functionality, enabling remote code execution with minimal user interaction. Most importantly, these attacks specifically targeted high-profile and sensitive organizations, thus proving that even well-established systems can harbor dangerous, undisclosed vulnerabilities.

Because the exploit hinges on the manipulation of the working directory when a .url file references a remote WebDav path, attackers managed to bypass many traditional security defenses. Besides that, this method leaves minimal forensic evidence, making detection and incident response particularly challenging. As reported by BleepingComputer and further analyzed by Kaspersky, this type of attack demonstrates the evolving threat landscape that organizations must confront.

Understanding the CVE-2025-33053 Vulnerability

CVE-2025-33053 is a remote code execution (RCE) vulnerability that stems from the improper handling of working directories in specific Windows system processes. Essentially, when a .url file uses a remote WebDav path erroneously, Windows may execute a malicious payload from the attacker’s server rather than from a local file. Therefore, even if no file is explicitly downloaded, the attacker’s code can run silently on the target machine.

Because of this, traditional defenses like antivirus software can struggle to detect a breach early on. In addition, this stealthy method of exploitation demands that security professionals rethink their monitoring strategies, as standard security events may not always flag these types of remote code executions.

Methods Employed by Attackers

An advanced threat group known as Stealth Falcon, also recognized by the moniker ‘FruityArmor,’ has been at the forefront of exploiting this vulnerability. Their campaign, which began in March 2025, targeted organizations across mixed geopolitical regions including Turkey, Qatar, Egypt, and Yemen. Using social engineering techniques, they sent tailored links leading to specially crafted WebDav URLs to unsuspecting users. Therefore, even a simple click could allow remote code execution on the victim’s device, making the threat particularly insidious. For further details, you can refer to the detailed analysis provided by BleepingComputer and Kaspersky.

Because the malware did not require local file drops, traditional scanning methods struggled to flag any suspicious activity. Besides that, the encrypted communication between infected devices and the remote WebDav servers allowed attackers to evade logging and routine network monitoring.

Impact and Scope of the Zero-Day Exploit

The scope of the attack is especially concerning given that it targeted organizations across multiple strategic regions. Even though there is no confirmed evidence yet that major systems were permanently compromised, the exploitation was indisputably active in the wild. Therefore, the possibility of similar vulnerabilities in other components of Windows cannot be ignored. As reported by CrowdStrike and Zero Day Initiative, exploiting such vulnerabilities not only endangers immediate targets but also shakes the foundation of trust in secure system architectures.

Moreover, the innovative technique of manipulating the working directory has prompted many security researchers to call for a reevaluation of remote execution safeguards. In essence, this incident should serve as a wakeup call for both industry professionals and the general public.

Mitigation Strategies and Protection Measures

Following responsible disclosure protocols from Check Point Research and other security authorities, Microsoft promptly addressed this vulnerability in its June 2025 Patch Tuesday update. Therefore, organizations must urgently apply these patches across all endpoints to mitigate the risk. Because timely patching is critical, extensive testing and verification should follow the patch deployment across all IT assets. As highlighted in the Microsoft Patch Tuesday announcement, failure to update systems promptly could leave networks exposed to similar exploits.

Besides that, companies should conduct regular audits of their IT assets to reduce unnecessary exposure. Furthermore, educating employees about the risks associated with clicking unsolicited links—especially those containing WebDav URLs—is essential to strengthen human-based defenses.

Monitoring network connections for suspicious outbound WebDav traffic and reviewing endpoint logs for anomalies are also practical steps. In addition, where WebDav is not essential for business operations, it should be disabled to narrow the attack surface.

Preparing for Future Threats

The exploitation of this Windows WebDav vulnerability offers crucial insights into the continually evolving tactics of Advanced Persistent Threat groups. Most importantly, it underscores the need for a proactive approach to cybersecurity—one that incorporates regular updates, awareness training, and advanced threat detection mechanisms. Therefore, organizations must shift from reactive to proactive postures in handling emerging vulnerabilities.

Because threat actors continue to leverage zero-day vulnerabilities and other obscure techniques, continuous investment in cybersecurity training and infrastructure is paramount. Besides that, collaboration with industry peers and cybersecurity experts is essential to stay ahead of emerging threats. According to CrowdStrike and the Zero Day Initiative, learning from these incidents is key to fortifying defenses against future attacks.

Ultimately, while this incident highlights how even mature operating systems can harbor hidden vulnerabilities, it also reinforces the importance of vigilance, timely software updates, and multidisciplinary collaboration to secure digital environments.

References and Further Reading

• Stealth Falcon hackers exploited Windows WebDav zero-day to drop malware (BleepingComputer)
• CVE-2025-33053: RCE in WebDAV (Kaspersky)
• June 2025 Patch Tuesday: Zero-Day and Critical Vulnerabilities Analysis (CrowdStrike)
• The June 2025 Security Update Review (Zero Day Initiative)
• Microsoft June 2025 Patch Tuesday fixes exploited zero-day, 66 flaws (BleepingComputer)