EDR-Redir is a recently disclosed technique that leverages two Windows kernel components: a Bind Filter driver (bindflt.sys) and the Windows Cloud Filter API (cldflt.sys). The Bind Filter is a type of mini-filter driver that can intercept and manipulate file system operations. By installing or abusing such a filter, attackers can redirect the file system path that an Endpoint Detection and Response (EDR) solution uses as its working folder to a location controlled by the attacker. Alternatively, the attacker can cause the folder to appear corrupted, preventing the EDR’s process services from functioning correctly. This effectively disables or bypasses the EDR’s ability to monitor and respond to threats on the system. The technique does not rely on a specific EDR product or version, making it potentially applicable to a broad range of Windows-based EDR solutions. No known exploits in the wild or patches have been reported, and public discussion is minimal, primarily limited to a Reddit post on the netsec subreddit. The attack impacts the integrity and availability of security monitoring tools, which could allow attackers to operate stealthily within compromised environments. The method requires kernel-level access or the ability to install kernel drivers, which may limit exploitation to attackers with elevated privileges or those who have already compromised the system to some extent. However, once executed, it can severely undermine endpoint security controls.

For European organizations, the impact of EDR-Redir could be significant. Disabling or bypassing EDR solutions compromises the primary line of defense against malware, ransomware, and advanced persistent threats (APTs). This increases the risk of prolonged undetected intrusions, data exfiltration, and operational disruption. Critical sectors such as finance, healthcare, energy, and government, which heavily rely on endpoint security solutions, would be particularly vulnerable. The ability to corrupt or redirect EDR working folders could also complicate incident response and forensic investigations, delaying remediation efforts. Given the widespread use of Windows and EDR products in Europe, the threat could affect a large number of enterprises, especially those with complex IT environments and legacy systems where kernel driver controls may be weaker. The lack of known exploits in the wild suggests this is an emerging threat, but its potential to undermine endpoint security warrants proactive attention.

Mitigation should focus on preventing unauthorized installation or manipulation of kernel-mode drivers such as bindflt.sys and cldflt.sys. Organizations should enforce strict driver signing policies and use Windows Defender Application Control (WDAC) or similar technologies to restrict kernel driver loads. Monitoring and alerting on changes to EDR working directories and related file system paths can help detect suspicious redirection or corruption attempts. Endpoint security teams should validate the integrity of EDR folders regularly and implement file system auditing to track unusual access patterns. Employing kernel-level monitoring tools that detect unauthorized mini-filter drivers or abnormal use of the Cloud Filter API can provide early warning. Additionally, maintaining least privilege principles to limit administrative access reduces the risk of attackers gaining the necessary permissions to deploy such techniques. Collaboration with EDR vendors to understand how their products interact with these Windows components and to receive updates or patches is also critical. Finally, organizations should incorporate this threat into their threat hunting and incident response playbooks.