Hackers Exploited Windows WebDav Zero-Day to Drop Malware

Summary

In a major cybersecurity development, an Advanced Persistent Threat (APT) group, known as ‘Stealth Falcon,’ has exploited a Windows WebDav Remote Code Execution (RCE) vulnerability.

This zero-day event has been occurring since March 2025, targeting high-profile organizations in Turkey, Qatar, Egypt, and Yemen.

The WebDav Zero-Day Exploit Revealed

WebDav or ‘Web Distributed Authoring and Versioning’ is an extension of the HTTP protocol that lets users collaborate on a centrally located file.

A zero-day vulnerability was recently discovered, and it’s being prominently exploited for delivering malware payloads to victims.

This vulnerability is an RCE, which, when exploited, allows hackers to run arbitrary code on a victim’s system, without any privilege escalation required – a gift for any attacker seeking to establish persistence and bypass traditional security solutions.

The high-profile victims are predominantly defense and government organizations, but the exploit’s general applicability makes all Windows users vulnerable.

Stealth Falcon’s Exploitation Techniques

‘Stealth Falcon’ is a seasoned hacking group previously attributed to many high-profile cyber-espionage campaigns.

In this instance, they are using phishing techniques to lure victims into clicking a link, which triggers the exploit.

The phishing emails sent by the group have been cleverly designed to appear legitimate, often disguising as urgent communications from government or corporate entities.

Once the link is clicked, the exploit triggers, and the RCE vulnerability in the Windows WebDav is used to drop malware onto the user’s computer.

Protecting Against the Zero-Day Exploit

As cybersecurity researchers work to create a patch for this zero-day vulnerability, users can take several steps to minimize their risk.

1. Upgrade systems: Always ensure your systems are running the most recent versions of software and that all patches have been installed.
2. Implement filters: Use email filters that can ostensibly limit the percentage of phishing attacks that reach user inboxes.
3. Educate users: The user is often the weakest link in the security chain.

   Carry out regular cybersecurity training to educate users about phishing techniques and how to identify and report suspicious emails.

Remember, stopping the first intrusion is only half the battle.

Ensuring a robust detection and response infrastructure is crucial if that first intrusion is missed.

Follow-Up Reading

1. Windows zero-days don’t die, they just fade away
2. Nation-State Zero Days: Finding Them is the Easy Part
3. Five Years After Stuxnet, No Fix By Vendors

As the landscape of cybersecurity rapidly evolves, it’s integral for professionals and organizations to stay updated on such threats.

With knowledge comes power, and in cybersecurity, power lies in the capability to anticipate, prevent, and respond to attacks.