Detecting Malicious Use of Process-Killing Tools: EDR Rules and SIEM Alerts

Stop the silent sabotage: detect opportunistic attackers using process-killers

Pain point: your EDR agent vanishes, monitoring gaps appear, or systems crash without obvious malware. Opportunistic attackers and commodity tools that kill processes are increasingly used to hide activity or destabilize environments. This guide gives concrete EDR and SIEM detection rules, telemetry recommendations, and a response playbook you can apply in 2026 to detect and disrupt process-termination attacks.

Why process-killers matter in 2026

Through late 2025 and into 2026 the threat landscape shifted: attackers favor lightweight, modular techniques to evade detection and move quickly. Rather than sophisticated kernel rootkits, many adversaries now rely on quick wins—terminating security tooling, wiping logs, or destabilizing services—using readily available utilities (taskkill, Stop-Process), small open-source binaries, or tiny custom loaders.

At scale, these opportunistic tactics let attackers avoid the cost and complexity of full stealth toolchains while still achieving rapid operational goals—encrypt files, stop backups, or cause cascading failures. Defenders must therefore treat process termination as a high-fidelity indicator when it happens in suspicious patterns: mass terminations, terminations of EDR/security processes, or terminations initiated by unusual parents.

How attackers use process termination (common patterns)

• EDR/AV tampering: killing or stopping EDR sensor processes and services (via taskkill, sc stop, or service control interfaces) before executing payloads.
• Mass disruption: automated scripts loop over process lists and force-terminate many processes to destabilize systems or trigger crashes.
• Living-off-the-land: abuse of built-in binaries (taskkill, wmic, powershell Stop-Process, sc.exe) to avoid dropping new artifacts.
• Code-based termination: custom binaries calling TerminateProcess or using NtTerminateProcess and OpenProcess(PROCESS_TERMINATE) directly.
• Process-hopping: terminate monitoring tools to disable telemetry, then execute memory-only payloads or ransomware.

Telemetry you must collect (and why)

Effective detection depends on the right telemetry. Prioritize these signals:

• Process creation and termination events (Windows Security 4688/4689 + Sysmon EventID 1 & 5). Capture full command line, parent process, and hashes where possible.
• Process access events (Sysmon EventID 10) to detect attempts to open processes with PROCESS_TERMINATE (0x0001) or PROCESS_ALL_ACCESS.
• Service control activity (Service Manager events, sc.exe usage, EventID 7045 for service creation, Service Control Manager events for starts/stops).
• PowerShell & script telemetry (ScriptBlock logging, Module logging, AMSI) to inspect obfuscated commands calling Stop-Process or calling TerminateProcess via .NET.
• Driver/kernel-level alerts from EDR that show protected process callbacks or blocked TerminateProcess attempts.
• Network & lateral movement indicators at the time of mass terminations—mass terminations with SMB auths or PsExec use is a high-risk combination.

High-value detection signals and thresholds

1. Termination of protected processes: any termination event where ProcessName matches a vetted security product (EDR, SIEM agent, backup agent). Immediate high priority.
2. Spike in terminations: more than N process terminations in a short window (example: >50 terminations in 60s on a workstation), correlated with CPU or I/O anomalies.
3. Process access with terminate rights: Sysmon EventID 10 where AccessMask includes 0x0001 (PROCESS_TERMINATE) and the target is a security process.
4. Terminations initiated by uncommon parents: e.g., explorer.exe or mshta.exe launching cmd.exe & then mass-killing trusted services.
5. Use of uncommon utilities: execution of binaries named pskill.exe, processhacker.exe, processroulette, killproc, or custom GUID-named exes in TEMP.

Sysmon-based detection rules (recommended)

Sysmon is indispensable here. Enable these features:

• EventID 1 (Process Create) with CommandLine capture
• EventID 5 (Process Terminated)
• EventID 10 (Process Access) with monitoring for AccessMask values matching terminate/open/modify

Example detection (Sysmon logs; adapt thresholds based on baseline):

# Pseudo-SQL / SIEM search against Sysmon
source="WinEventLog" EventID=5 OR (EventID=10 AND TargetImage IN ("*\MsMpEng.exe","*\csagent.exe","*\carbonblack.exe","*\crowdstrike.exe"))
| stats count as terminations by Computer, TargetImage, User
| where terminations > 0
| sort - terminations

Example focused rule: trigger when Sysmon EventID 10 shows a process requesting PROCESS_TERMINATE against any EDR sensor process:

# Sysmon EventID 10: detect terminate access
EventID=10
| where TargetImage in ("C:\\Program Files\\CrowdStrike\\CSFalconService.exe","C:\\Program Files\\CarbonBlack\\cb.exe","C:\\Program Files\\Windows Defender\\MsMpEng.exe")
| where AccessMask contains "0x1" OR AccessMask contains "PROCESS_TERMINATE"
| table TimeCreated, Computer, SubjectUserName, Image, TargetImage, AccessMask, CommandLine

Sample SIEM queries (Splunk & Elastic)

Splunk (Windows Security + Sysmon)

index=wineventlog (EventCode=4689 OR (SourceName="Microsoft-Windows-Sysmon" AND EventID=5))
| eval proc=coalesce(Image,ProcessName)
| stats count by _time, ComputerName, proc, User
| where count > 20
| sort - count

Elastic / Kibana (winlogbeat + sysmon)

# Find process terminations and highlight if target is an EDR
winlog.event_id: 5 or winlog.event_id: 4689
| where process.name: ("MsMpEng.exe" OR "csagent.exe" OR "cb.exe" OR "DefenderService.exe")
| aggregate by host.name, process.name, user.name, event.outcome | where count > 0

Microsoft 365 Defender / Advanced Hunting (KQL) examples

Use DeviceEvents and DeviceProcessEvents to correlate process access and terminations. Example KQL (adapt to your schema):

// Show processes that terminated sensor or antimalware processes
DeviceProcessEvents
| where FileName in ("taskkill.exe","powershell.exe","cmd.exe","wmic.exe")
| where ProcessCommandLine contains "MsMpEng" or ProcessCommandLine contains "CrowdStrike"
| project Timestamp, DeviceName, InitiatingProcessFileName, FileName, ProcessCommandLine
| take 50

Sigma rule (generic) — detect terminate rights and protected process terminations

title: Termination of security/sensor process
logsource:
  product: windows
  service: sysmon
detection:
  selection1:
    EventID: 10
    TargetImage|contains:
      - "MsMpEng.exe"
      - "CSFalconService.exe"
      - "CbSensor.exe"
    AccessMask|contains: "0x1"
  selection2:
    EventID: 5
    Image|contains:
      - "MsMpEng.exe"
      - "CSFalconService.exe"
      - "CbSensor.exe"
  condition: selection1 or selection2
level: high

Vendor-focused EDR detections — examples (templates)

Below are practical, vendor-agnostic templates you can adapt to your EDR policy language.

CrowdStrike / Carbon Black style alert

• Trigger if process terminates a protected agent process OR a script executes taskkill /f against a protected process.
• Collect: parent PID, command line, SHA256 of the terminator, process token elevation, and network connections at time of event.
• Automated response: isolate host, kill terminator process, and snapshot memory of terminated process if available.

Microsoft Defender for Endpoint (Automated Investigation)

• Hunt for DeviceProcessEvents where InitiatingProcessFileName in ("powershell.exe","cmd.exe","taskkill.exe") and ProcessCommandLine contains names of security products.
• Auto-respond: block the hash, collect forensic package, restrict account used for execution.

Behavioral & anomaly detections (advanced)

Static rules catch a lot, but attackers adapt. Add behavioral detection:

• Rate-based anomaly: compute per-host baseline of process terminations per minute. Alert when deviation > X standard deviations.
• Sequence detection: chain events—process access (Sysmon 10) followed by process termination (5) then log clearing or service stop.
• Parent-child inconsistency: parent process not normally seen initiating terminations (e.g., explorer.exe acting as orchestrator of mass kills).
• Temporal correlation: mass termination concurrent with pattern of lateral movement (remote service creation, SMB activity).

Forensics: what to collect immediately

When an alert fires, preserve best-evidence artifacts quickly. Prioritize:

1. Full memory image (if possible) for root-cause and to recover process artifacts.
2. Process dumps for both the terminator and terminated security process.
3. Sysmon and Windows Event logs (Export-WinEvent or “wevtutil epl”), with sequence around the incident time.
4. Network captures or flows for the incident window.
5. File system forensic copy of any unfamiliar binary (compute sha256 via certutil/Get-FileHash).

Example commands to compute file hash on Windows (store the hash in your case notes):

certutil -hashfile C:\\Temp\\suspicious.exe SHA256
# or PowerShell
Get-FileHash C:\\Temp\\suspicious.exe -Algorithm SHA256

Response playbook: contain, collect, and remediate

Quick, consistent steps reduce blast radius.

1. Elevate and isolate: isolate the host from the network (EDR network isolation) and disable accounts used for the action.
2. Preserve and collect: do the forensics collection above. If memory collection isn't possible, export relevant logs and process dumps immediately.
3. Remediate the attacker foothold: remove discovered persistence, block hashes, and revoke credentials used.
4. Restore and harden: patch, reimage if necessary, and ensure EDR self-protection is enabled and policies are hardened (prevent service stop/alteration).
5. Hunt & lateral check: search the environment for matching hashes, similar command lines, or parent process patterns to identify other compromised hosts.

Case study: red team exercise (controlled lab, Dec 2025)

In our December 2025 red team exercise, the blue team detected a sequence that illustrates the attack lifecycle and the value of process-access telemetry. The red team executed a tiny C# utility that opened the EDR service process with PROCESS_TERMINATE and then called TerminateProcess. Sysmon EventID 10 showed the access attempt; EventID 5 recorded the termination. The SIEM rule tuned to watch for AccessMask=0x1 against known sensors fired before the mass termination. The early alert enabled memory capture and prevented the subsequent ransomware payload from executing across additional hosts.

Lesson: process access telemetry (Sysmon 10) often provides earlier detection than waiting for termination events alone.

Hardening & prevention strategies

• Enable EDR self-protection and tamper protection features; require signing and protected service policies for agents.
• Harden administrative workflows: reduce local admin assignments, audit and restrict credentials for remote management tools.
• Implement application allowlisting for critical services and agents so unknown terminators cannot execute.
• Use kernel-level hooks or driver-based protections where your EDR supports it to block TerminateProcess attempts against protected processes.
• Deploy deception: create decoy services/processes that look like attractive targets to detect opportunistic attacks.

Measuring detection effectiveness (KPIs)

Track these metrics to measure program maturity:

• Detection lead time: interval from process-access (Sysmon 10) to alert.
• False positive rate on process termination alerts.
• Percentage of terminations blocked by EDR self-protection.
• Time to isolate after detection.

Future predictions & 2026 trends

Expect an increase in script-based and living-off-the-land process attacks through 2026. However, EDR vendors are improving kernel-level protections and tamper resistance. Defenders should pair low-level telemetry (process access masks, kernel callbacks) with anomaly detection to catch both commodity and bespoke termination techniques. Automation—especially automated containment and memory capture—will be central to minimizing attacker dwell time.

Actionable takeaways

• Enable and collect Sysmon EventID 1, 5, and 10 with full command-line capture.
• Create SIEM alerts for process access with terminate rights against security products and for mass termination spikes.
• Automate containment on high-confidence alerts (isolate host, collect memory, block binaries).
• Hunt for parent-child anomalies and correlate terminations with lateral movement signals.
• Test periodically with red-team exercises and simulate process-killer tools to validate detection and response.

Final checklist to deploy today

1. Enable Sysmon with EventID 1, 5, 10 and capture command line.
2. Deploy SIEM alerts using the queries/examples provided; tune thresholds to your environment.
3. Implement EDR automated containment and ensure process self-protection is on.
4. Create response playbooks and run a tabletop or red-team drill focused on process-termination attacks.
5. Measure KPIs and iterate: reduce detection lead time and false positives.

Call to action

If you want ready-to-deploy templates for Splunk, Elastic, Microsoft Defender, or a Sigma ruleset tuned to your baseline, export the telemetry described above and download our detection pack for immediate deployment. Run the included simulation scripts in a lab to validate your pipeline before you need it in production.

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