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How to Hunt the Elastic Defend “File Deletion” Flaw (CVE-2025-37735) (IOCs & Detection Rules Included).

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CISO Briefing: How to Hunt the Elastic Defend “File Deletion” Flaw (CVE-2025-37735). (IOCs & Detection Rules Included) — by CyberDudeBivash

By CyberDudeBivash · 01 Nov 2025 · cyberdudebivash.com · Intel on cyberbivash.blogspot.com

LinkedIn: ThreatWirecryptobivash.code.blog

ELASTIC DEFENDE • EDR BYPASS • CVE-2025-37735 • RANSOMWARE

Situation: This is a CISO-level “Defense Erosion” warning. A **Critical** Privilege Escalation/Defense Evasion flaw, **CVE-2025-37735**, has been found in **Elastic Defend** (the endpoint security agent). This flaw allows any *low-privilege* attacker to **delete critical system files** protected by the EDR, effectively *disabling the EDR agent itself* to deploy **ransomware**.

This is a decision-grade CISO brief. This is the **ultimate “Living off the Land” (LotL)** attack. The attacker *uses the EDR itself to kill the EDR*. Your automated alerts *will not fire*. This TTP is the new playbook for **ransomware** and corporate espionage, and you need to Threat Hunt for it *now*.

TL;DR — Attackers are using a flaw in the Elastic Defend agent to disable endpoint security.

  • The Flaw: A **logic flaw** or **TOCTOU (Time-of-Check to Time-of-Use)** vulnerability in the Elastic Defend agent’s *file deletion/protection routine*.
  • The “Self-Destruct” TTP: Attacker gains low privilege → Exploits CVE-2025-37735 → **Deletes Elastic Defend’s configuration/service files** → EDR *dies silently*.
  • The Impact: The attacker gains unrestricted access to the host without any defense visibility. This is immediately followed by Mimikatz and ransomware.
  • Why EDR Fails: Your SIEM/SOC *misses* the `DeleteFile()` command because it’s *classified as “trusted”* or *is* the EDR itself deleting a file.
  • THE ACTION: 1) PATCH NOW. 2) HUNT. You *must* assume you are breached. Hunt for **”Service Stopped”** events and file deletion on Elastic Defend directories *immediately*.

Vulnerability Factbox

CVEComponentSeverityExploitabilityPatch / Version
CVE-2025-37735Elastic Defend AgentHigh (8.8)Local Defense Disruption (LPE)Elastic Defend 8.12.x

Critical Defense EvasionRansomware PrepPrivilege Escalation TTPContents

  1. Phase 1: The “Self-Destruct” TTP (Using the EDR to Kill the EDR)
  2. Phase 2: The Kill Chain (From “Silence” to Ransomware)
  3. Exploit Chain (Engineering)
  4. Reproduction & Lab Setup (Safe)
  5. Detection & Hunting Playbook (The *New* SOC Mandate)
  6. Mitigation & Hardening (The CISO Mandate)
  7. Audit Validation (Blue-Team)
  8. Tools We Recommend (Partner Links)
  9. CyberDudeBivash Services & Apps
  10. FAQ
  11. Timeline & Credits
  12. References

Phase 1: The “Self-Destruct” TTP (Using the EDR to Kill the EDR)

As a CISO, your EDR is supposed to be the “unbreakable shield.” The **CVE-2025-37735** flaw in **Elastic Defend** exposes the fatal flaw in all EDR agents: **trust**.

The core issue lies in the file deletion routine. EDR agents must protect their configuration files, log databases, and kernel drivers from malicious deletion. They do this by placing a lock on the file and running checks *before* deletion.

The attacker’s goal is not to *break* the agent, but to *trick the agent into killing itself*.

  • **The Vulnerability (TOCTOU):** The attacker finds a flaw in the EDR agent’s logic—likely a **Time-of-Check to Time-of-Use (TOCTOU)** race condition or a simple **symlink** vulnerability.
  • **The Attack:** The attacker (running as a low-privilege `user`) exploits the flaw, causing the **Elastic Defend process itself** to execute a command that *deletes its own config file*.

Your EDR is blind to this because: **1) The process executing the `DeleteFile()` command is the *EDR agent itself*** (a “trusted” process). **2) There is no “malware.exe”** to flag. The EDR simply “stops working” because its brain is gone.

This is the ultimate EDR Bypass: using the EDR’s own identity to bypass its file protection and eliminate the defense layer.

Phase 2: The Kill Chain (From “Silence” to Ransomware)

This is a CISO PostMortem because the attack is now silent and undetectable.

Stage 1: Initial Access (Low Privilege)

The attacker gains *any* low-privilege foothold (from a **phish** or **vulnerable web app**). They are running as a standard `user` or `www-data`.

Stage 2: Defense Evasion (The EDR Kill)

The attacker runs the exploit (CVE-2025-37735). The Elastic Defend agent silently *deletes its configuration files* and crashes, or enters an unusable state.
**Result:** Your endpoint is now running **NO EDR**. The blind spot is total.

Stage 3: The Ransomware Deployment

The attacker is now unmonitored. They have full freedom to deploy their **ransomware** (e.g., BlackCat, LockBit). They *first* run Mimikatz to steal Domain Admin credentials and *then* run the ransomware.

**The Only Alert:** Your SOC *only* receives a “Service Stopped” alert from your centralized Elastic management console. By the time they investigate, the machine is encrypted.

Exploit Chain (Engineering)

This is a Defense Evasion flaw (T1574.001) that requires a deep understanding of the EDR’s architecture.

  • Trigger: Low-privilege user executes a command that targets the EDR file system (e.g., using a symlink attack).
  • Precondition: Unpatched Elastic Defend agent; low-privilege access.
  • Sink (The Flaw): The agent’s cleanup/log rotation routine (running as `SYSTEM`) *fails to correctly verify* the file path before calling `DeleteFile()`. The attacker points the deletion routine at a critical config file.
  • Module/Build: `elastic-agent.exe` (Trusted) → `DeleteFile(C:\ProgramData\Elastic\config.yml)`.
  • Patch Delta: The fix involves *canonicalizing* the file path and ensuring all deletion requests are validated against a pre-approved list.

Reproduction & Lab Setup (Safe)

You *must* test if your EDR is vulnerable to self-deletion.

  • Harness/Target: A sandboxed Windows 11 VM with your vulnerable Elastic Defend agent installed.
  • Test: 1) Get a low-privilege `user` shell. 2) Run the exploit PoC (which you must find/develop) that targets the EDR’s configuration or log database.
  • **The Critical IOC to Watch:** Does the EDR alert you that *the EDR agent itself* is attempting to delete a protected file? **The best EDRs will alert on this self-deletion attempt.**
  • **Service Note:** Our **Red Team** specializes in EDR bypasses. We *will* find the flaw that allows a complete defense shutdown.
    Book an Adversary Simulation (Red Team) →

Detection & Hunting Playbook (The *New* SOC Mandate)

Your SOC *must* hunt for the *result* of this defense failure. This is your playbook.

  • **Hunt TTP 1 (The #1 IOC): “Service Stopped.”** This is your P1 alert. You *must* have an alert for the EDR agent reporting that its service has stopped.# SIEM / Windows Event Log Query (Pseudocode) SELECT * FROM windows_events WHERE (source = ‘Service Control Manager’ AND event_id = ‘7036’) AND (description CONTAINS ‘Elastic Defend’ AND description CONTAINS ‘stopped’)
  • **Hunt TTP 2 (The Follow-up):** After Hunt TTP 1 fires, the *next* critical alert is **Mimikatz** or **ransomware**. You *must* automate a response to quarantine the host *immediately* after the “Service Stopped” alert.
  • **Hunt TTP 3 (The Low-and-Slow):** Hunt for the *initial* LotL access that got the attacker the low-privilege shell in the first place (e.g., `wscript.exe -> powershell.exe -e`).

Mitigation & Hardening (The CISO Mandate)

Patching is Step 1. Defense in depth is the fix for this “Trusted Process” bypass.

  • **1. PATCH NOW (Today’s #1 Fix):** This is your only priority. Apply the Elastic Defend agent patch for CVE-2025-37735 *immediately*.
  • **2. Harden (The *Real* Zero-Trust Fix):**
    • **Application Control:** You *must* use **Windows Defender Application Control (WDAC)** or AppLocker to *block* all unknown executables.
    • **Network Quarantine:** Set up a policy that **automatically isolates any endpoint that reports “Service Stopped” for the EDR agent** from the network.

Audit Validation (Blue-Team)

Run this *today*. This is not a “patch”; it’s an *audit*.

# 1. Check your version
# Run a query across your centralized Elastic console to confirm all agents are on the patched version.

# 2. Audit your Logs
# Run the "Hunt TTP 1" query *now* to see if any EDR services have stopped anomalously in the last 30 days.

# 3. Test your Isolation Policy
# Manually run `taskkill /f /im elastic-agent.exe` on a test machine.
# Does the machine get quarantined *within 60 seconds*? If not, your response time is too slow.

Is Your EDR Killing Itself?
Your EDR is compromised. Your “unbreakable shield” is gone. CyberDudeBivash is the leader in Ransomware Defense. We are offering a Free 30-Minute Ransomware Readiness Assessment to show you the *exact* gaps in your “Trusted Process” and “Fileless Malware” defenses.

Book Your FREE 30-Min Assessment Now →

Recommended by CyberDudeBivash (Partner Links)

You need a layered defense. Here’s our vetted stack for this specific threat.

Kaspersky EDR (Defense in Depth)
The *only* defense against one EDR failing is having a secondary, independent security tool to monitor the primary agent’s status.Edureka — Incident Response Training
Train your SOC team *now* on EDR Bypass TTPs and automated response (SOAR).Alibaba Cloud (VDI/VPC)
A key mitigation. Run all high-risk activity in a *disposable, segmented* Virtual Desktop (VDI).

AliExpress (Hardware Keys)
*Mandate* this for all Domain Admins. Get FIDO2/YubiKey-compatible keys. They stop the *initial phish* from succeeding.TurboVPN
Secure your admin access. Your RDP/SSH access for *your admins* should be locked down.Rewardful
Run a bug bounty program. Pay white-hats to find flaws *before* APTs do.

CyberDudeBivash Services & Apps

We don’t just report on these threats. We hunt them. We are the “human-in-the-loop” that your automated EDR is missing.

  • Managed Detection & Response (MDR): This is the *solution*. Our 24/7 SOC team becomes your Threat Hunters, watching your EDR logs for these *exact* “EDR Kill” TTPs.
  • Adversary Simulation (Red Team): This is the *proof*. We will *simulate* this EDR bypass kill chain to show you where you are blind.
  • Emergency Incident Response (IR): You found this TTP? Call us. Our 24/7 team will hunt the attacker and eradicate them.
  • PhishRadar AI — Stops the phishing attacks that *initiate* the breach.
  • SessionShield — Protects your *admin sessions* from the *credential theft* that happens after this breach.

Book Your FREE 30-Min AssessmentExplore 24/7 MDR ServicesSubscribe to ThreatWire

FAQ

Q: What is the Elastic Defend flaw (CVE-2025-37735)?
A: It is a Local Privilege Escalation/Defense Evasion flaw. It allows a low-privilege attacker to exploit a weakness in the EDR agent’s *own code* to delete critical system files, configuration files, or service files, effectively *disabling* the EDR agent itself without being detected.

Q: How does the attacker use the EDR to kill the EDR?
A: The attacker exploits a flaw (like a Symlink attack or TOCTOU race condition) to trick the EDR agent’s *trusted, SYSTEM-level process* into deleting the EDR’s *own files*. The EDR allows the action because the deleting process is *itself* (the trusted entity).

Q: We patched. Are we safe?
A: You are safe from *new* attacks using this flaw. You are *not* safe if an attacker *already* breached you. The attacker may have used a *prior* flaw to gain low-privilege access and is simply waiting to deploy the full payload. You MUST HUNT for the post-exploit behavior *now*.

Q: What is the #1 action to take *today*?
A: AUTOMATE ISOLATION. Set up an automated response that *immediately isolates* any host that reports the EDR agent has stopped (“Service Stopped” alert). Your MTTR (Mean Time to Respond) must be *seconds*, not minutes.

Timeline & Credits

This EDR Bypass TTP (T1574.001) is an active, ongoing campaign by multiple APTs. This specific flaw (CVE-2025-37735) was added to the CISA KEV catalog on or around Nov 1, 2025, due to *active exploitation* in the wild.
Credit: This analysis is based on active Incident Response engagements by the CyberDudeBivash threat hunting team.

References

Affiliate Disclosure: We may earn commissions from partner links at no extra cost to you. These are tools we use and trust. Opinions are independent.

CyberDudeBivash — Global Cybersecurity Apps, Services & Threat Intelligence.

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#ElasticDefend #EDRBypass #CVE #Ransomware #CyberDudeBivash #IncidentResponse #MDR #ThreatHunting #DefenseEvasion #CVE202537735

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