Attackers want quiet ways to cut visibility. EDR-Redir V2 targets Microsoft Defender on Windows 11 by abusing Windows bind links so Defender looks healthy while it loses access to its own working paths. Because the redirection occurs in the minifilter stack, surface-level checks often pass. However, careful validation exposes the misdirection and lets you restore telemetry quickly.
๐๐ข๐ง๐ ๐๐ข๐ง๐ค ๐๐๐ฎ๐ฌ๐ ๐ญ๐จ ๐๐ฅ๐ข๐ง๐ ๐๐๐๐๐ง๐๐๐ซ
Windows uses minifilter drivers to shape file I/O. bindflt.sys implements bind links that map one path to another. cldflt.sys supports Cloud Files semantics. EDR-Redir V2 leverages these components to reroute folders under Program Files or ProgramData. Then Defenderโs processes try to read and write as usual, yet the filesystem silently points them to a different location or loops resolution so operations fail. Consequently, alerts drop, sensor writes miss, and investigations slow down even though services continue to run.
๐๐ซ๐๐๐จ๐ง๐๐ข๐ญ๐ข๐จ๐ง๐ฌ ๐๐ง๐ ๐๐๐จ๐ฉ๐
The operator needs administrative privileges on a Windows 11 host (or a supported Windows 10 build with these filters). Defender for Endpoint runs in the environment, sometimes with Defender Antivirus in active or passive mode. Because the manipulation lives below user-mode, service status can appear normal while EDR files resolve elsewhere.
๐๐ฑ๐ฉ๐ฅ๐จ๐ข๐ญ๐๐ญ๐ข๐จ๐ง ๐ ๐ฅ๐จ๐ฐ
First, the operator profiles C:\Program Files and C:\ProgramData to understand where security components live. Next, they mirror subfolders to a controlled directory such as C:\TMP\TEMPDIR. Then they create bind links that loop most folders back to themselves to preserve application behavior. Critically, they exclude the EDRโs own directory and redirect only that path to the controlled mirror. Example syntax from public demonstrations resembles: EDR-Redir.exe C:\ProgramData\Microsoft C:\TMP\TEMPDIR “C:\ProgramData\Microsoft\Windows Defender”. After execution, Defender continues to run; however, the working directory reads and writes inside TEMPDIR, which degrades telemetry and corrupts assumptions inside the EDR stack.
๐๐ซ๐ญ๐ข๐๐๐๐ญ๐ฌ ๐๐ง๐ ๐๐ฉ๐๐ซ๐๐ญ๐ข๐จ๐ง๐๐ฅ ๐๐ข๐๐ ๐๐๐๐๐๐ญ๐ฌ
Expect bind links under sensitive parents. Watch minifilter altitudes and load-order for irregularities tied to bindflt and cldflt. Some hosts show subtle path-resolution errors without obvious service failures. More importantly, watch for alert volume and event count drops that begin close to the time the links appear. Because the goal is silence, you often see gaps rather than explicit errors.
๐๐ก๐ฒ ๐๐ซ๐จ๐ ๐ซ๐๐ฆ ๐ ๐ข๐ฅ๐๐ฌ ๐๐๐๐ข๐ซ๐๐๐ญ๐ข๐จ๐ง ๐๐๐ญ๐ญ๐๐ซ๐ฌ
EDR-Redir V2 extends prior folder-targeted tricks by going one level up to the parent folder (for example, Program Files). By looping non-EDR subfolders back to themselves, the environment continues to work for most applications. Meanwhile, a single exception the EDRโs own folder routes to a location the attacker controls. Therefore, the change hides within normal operations while it denies the EDR reliable file access.
๐๐๐ญ๐๐๐ญ๐ข๐จ๐ง ๐๐ง๐ ๐๐๐ฅ๐ข๐๐๐ญ๐ข๐จ๐ง
Start with health, then verify the filesystem and filters.
โข Enumerate bind links beneath Program Files and ProgramData; compare against a baseline.
โข Inspect minifilter altitudes and groups to confirm expected ordering for bindflt and cldflt.
โข Check Defender event volume and EDR in block mode behavior; identify sudden gaps that align with link creation.
โข Remove suspicious links or restore expected paths; then validate that telemetry returns to prior rates.
Because attackers avoid noise, compare yesterday vs. today per-host event counts and flag sharp drops that match filter changes.
๐๐ข๐ญ๐ข๐ ๐๐ญ๐ข๐จ๐ง ๐๐ง๐ ๐๐๐ซ๐๐๐ง๐ข๐ง๐
Treat any bind link that touches security tooling as hostile unless explicitly justified. Enforce tamper protection, reduce local admin abuse through policy, and baseline approved bind links so you can alert on drift. Where feasible, monitor and protect bindflt and cldflt states, including administrative actions that create or modify links. After cleanup, re-enable or confirm EDR in block mode, validate event throughput, and log the configuration so change control doesnโt roll it back.
๐๐ฎ๐ฌ๐ข๐ง๐๐ฌ๐ฌ ๐๐ฆ๐ฉ๐๐๐ญ ๐๐ง๐ ๐๐ข๐ฌ๐ค
When EDR paths misroute, investigations slow and dwell time rises. Telemetry gaps help lateral movement and ransomware staging. Even if you do not see broad exploitation today, the low complexity and quiet footprint make the technique appealing. Therefore, your control objective becomes continuous filter-layer validation, not episodic fixes.
๐๐๐ฌ๐ฌ๐จ๐ง๐ฌ ๐๐๐๐ซ๐ง๐๐
Bake a standing control into endpoint management that inventories bind links and minifilter state on every device. Track changes over time. Alert on new links under sensitive parents. Coordinate with platform owners so integrity checks do not block legitimate updates or cloud-sync features. Above all, treat EDR health as a monitored asset and watch for quiet failures, not only explicit errors.
๐ ๐๐๐ฌ
๐๐จ๐๐ฌ ๐ญ๐ก๐ข๐ฌ ๐ซ๐๐ช๐ฎ๐ข๐ซ๐ ๐ค๐๐ซ๐ง๐๐ฅ-๐ฆ๐จ๐๐ ๐๐จ๐๐?
No. It abuses supported filter behavior but still needs administrative privileges.
๐๐ข๐ฅ๐ฅ ๐๐๐ ๐ข๐ง ๐๐ฅ๐จ๐๐ค ๐ฆ๐จ๐๐ ๐ฌ๐ญ๐จ๐ฉ ๐ข๐ญ?
Block mode helps, yet path misdirection can still degrade telemetry. Always validate block mode after remediation.
๐๐ก๐๐ญ ๐ฌ๐ก๐จ๐ฎ๐ฅ๐ ๐ฐ๐ ๐ฆ๐จ๐ง๐ข๐ญ๐จ๐ซ ๐ฅ๐จ๐ง๐ ๐ญ๐๐ซ๐ฆ?
Track bind link creation, minifilter altitudes, Defender health, and event volume trends. Alert on gaps and drift rather than waiting for a single error log.
