Microsoft Defender Antivirus event log
Windows Defender/Operational event channel: malware detections and the remediation chain, protection disabled and re-enabled, configuration changes that resemble tampering, definition and engine failures, ASR and network-protection blocks, and the heartbeat and scan lifecycle retained at the Debug severity tier. The health-center channel (WHC) is collected too when the host has it. The channel does not exist on Windows Server 2012 R2, where this source yields nothing. Nothing is deleted; routine events are lowered in severity, not removed.
Feed id: win.defender.eventlog.
Channels
This feed binds 2 Windows Event Log channels as one reporting axis. A channel that a given Windows edition, role or OEM does not provide is absent on that endpoint; the rest still collect.
| Channel | Ticket class |
|---|---|
Microsoft-Windows-Windows Defender/Operational | |
Microsoft-Windows-Windows Defender/WHC |
Curated reasons
Severity here is what the condition is worth to the person holding the ticket, not the level the provider stated for itself.
| Reason | Ticket class | Severity |
|---|---|---|
av_config_changed | endpoint_protection | Warning |
av_definition_update_failed | endpoint_protection | Error / Warning |
av_engine_failed | endpoint_protection | Error |
av_protection_disabled | endpoint_protection | Serious or Notice |
av_scan_failed | endpoint_protection | Warning |
av_suspicious_behavior_detected | endpoint_protection | Warning |
av_tamper_blocked | endpoint_protection | Warning |
av_threat_detected | endpoint_protection | Error or Warning |
av_threat_not_remediated | endpoint_protection | Serious |
av_threat_remediated | endpoint_protection | Warning |
av_threat_remediation_failed | endpoint_protection | Error |
defender_asr_block | endpoint_protection | Warning |
defender_network_protection_block | endpoint_protection | Warning |
av_config_changed
Microsoft Defender recorded a configuration change to a protection-sensitive setting.
Severity: Warning
Impact: Exclusions or protection settings may have changed, which can weaken prevention, detection, or cloud reporting.
Channel: Microsoft-Windows-Windows Defender/Operational
Provider: Microsoft-Windows-Windows Defender
Event ids: 5007
Where to look next:
- Review Old Value and New Value.
- Check whether the change came from approved GPO, Intune, or EDR policy.
Related reasons:
av_protection_disabled: protection state changed directlyav_tamper_blocked: attempted settings change blocked by tamper protection
Fields it can set: win.defender.eventlog.new_value, win.defender.eventlog.old_value
av_definition_update_failed
Microsoft Defender failed to update or reverted security intelligence.
Severity: Error / Warning
Impact: Defender may scan with stale or rolled-back signatures until a later update succeeds.
Channel: Microsoft-Windows-Windows Defender/Operational
Provider: Microsoft-Windows-Windows Defender
Event ids: 2001, 2003, 2004
Where to look next:
- Review Current and Previous security intelligence Version.
- Look for later successful update events before opening a stale-definitions incident.
Related reasons:
av_engine_failed: engine failure rather than update failureav_scan_failed: scan coverage issue
Fields it can set: win.defender.eventlog.sig_version, win.defender.eventlog.sig_version_previous, win.defender.eventlog.status
av_engine_failed
Microsoft Defender reported a protection feature or engine failure.
Severity: Error
Impact: Endpoint protection may be degraded until the feature or engine recovers.
Channel: Microsoft-Windows-Windows Defender/Operational
Provider: Microsoft-Windows-Windows Defender
Event ids: 3002, 5008
Where to look next:
- Review Feature Name and Error Code.
- Look for later 3007 recovery context.
Related reasons:
av_definition_update_failed: update path failureav_protection_disabled: explicit protection-state change
Fields it can set: win.defender.eventlog.feature_name, win.defender.eventlog.status
av_protection_disabled
Microsoft Defender protection was disabled, or later re-enabled for the same protection family.
Severity: Serious or Notice
Impact: While disabled, Defender may not provide the expected real-time, antispyware, or antivirus protection for the host.
Channel: Microsoft-Windows-Windows Defender/Operational
Provider: Microsoft-Windows-Windows Defender
Event ids: 5000, 5001, 5009, 5010, 5011, 5012
| Case | Severity | Ticket class |
|---|---|---|
disabled | Serious | endpoint_protection |
enabled | Notice | endpoint_protection |
Where to look next:
- Check whether Intune, GPO, installer activity, or an admin action caused the change.
- Pair disabled and enabled events before judging duration.
Related reasons:
av_config_changed: configuration changes that can weaken protectionav_engine_failed: engine failure can also reduce protectionav_tamper_blocked: attempted change blocked by tamper protection
av_scan_failed
A Microsoft Defender scan failed before completing.
Severity: Warning
Impact: The host may have missed scheduled or requested malware scanning coverage for that run.
Channel: Microsoft-Windows-Windows Defender/Operational
Provider: Microsoft-Windows-Windows Defender
Event ids: 1005
Where to look next:
- Review Scan ID and Error Code.
- Distinguish scan failed from scan cancelled.
Related reasons:
av_definition_update_failed: stale definitions can reduce scan valueav_threat_detected: what a later scan may find
Fields it can set: win.defender.eventlog.scan_id, win.defender.eventlog.status
av_suspicious_behavior_detected
Microsoft Defender behavior monitoring detected suspicious behavior.
Severity: Warning
Impact: A process or file behaved in a way Defender considered suspicious; later threat outcome events may clarify whether it was blocked or cleaned.
Channel: Microsoft-Windows-Windows Defender/Operational
Provider: Microsoft-Windows-Windows Defender
Event ids: 1015
Where to look next:
- Review Threat Name, Path, and Process Name.
- Look for adjacent detection or remediation events.
Related reasons:
av_threat_detected: malware or PUA detection in the same channelav_threat_remediation_failed: cleanup failure after a detection
Fields it can set: win.defender.eventlog.process_name, win.defender.eventlog.threat_name, win.defender.eventlog.threat_path
av_tamper_blocked
Microsoft Defender tamper protection blocked a settings change.
Severity: Warning
Impact: A protection weakening attempt was blocked; repeated events may indicate a misapplied policy or hostile tampering.
Channel: Microsoft-Windows-Windows Defender/Operational
Provider: Microsoft-Windows-Windows Defender
Event ids: 5013
Where to look next:
- Look for nearby configuration changes and policy refreshes.
- Treat repeated 5013 events differently from a one-time management action.
Related reasons:
av_config_changed: completed Defender configuration changeav_protection_disabled: protection actually disabled
av_threat_detected
Microsoft Defender detected malware or potentially unwanted software.
Severity: Error or Warning
Impact: A threat was present or suspected on the host; cleanup status depends on later remediation events.
Channel: Microsoft-Windows-Windows Defender/Operational
Provider: Microsoft-Windows-Windows Defender
Event ids: 1006, 1116
| Case | Severity | Ticket class |
|---|---|---|
high_severity | Error | endpoint_protection |
standard | Warning | endpoint_protection |
Where to look next:
- Pivot on Threat Name, Path, Process Name, Detection Source, and User.
- Pair with the later 1117, 1118, or 1119 outcome.
Related reasons:
av_threat_not_remediated: Defender allowed the threat instead of remediating itav_threat_remediated: Defender reports an action was takenav_threat_remediation_failed: Defender tried to remediate and failed
Fields it can set: win.defender.eventlog.category_id, win.defender.eventlog.category_name, win.defender.eventlog.detection_origin, win.defender.eventlog.detection_source, win.defender.eventlog.detection_type, win.defender.eventlog.process_name, win.defender.eventlog.severity_id, win.defender.eventlog.severity_name, win.defender.eventlog.threat_name, win.defender.eventlog.threat_path, win.defender.eventlog.user
av_threat_not_remediated
Microsoft Defender recorded a detection outcome where the item was allowed instead of remediated.
Severity: Serious
Impact: Potentially unwanted or malicious software may remain active or available on the host.
Channel: Microsoft-Windows-Windows Defender/Operational
Provider: Microsoft-Windows-Windows Defender
Event ids: 1007, 1117
Where to look next:
- Validate who or what policy allowed the item.
- Review Threat Name, Path, Process Name, User, and exclusion policy.
Related reasons:
av_threat_detected: detection that usually precedes the outcomeav_threat_remediated: same event family when Defender took a remediation actionav_threat_remediation_failed: attempted remediation failed instead of allowing the item
Fields it can set: win.defender.eventlog.action_id, win.defender.eventlog.action_name, win.defender.eventlog.process_name, win.defender.eventlog.status, win.defender.eventlog.threat_name, win.defender.eventlog.threat_path, win.defender.eventlog.user
av_threat_remediated
Microsoft Defender took a remediation action for a detected threat.
Severity: Warning
Impact: The host had a threat finding; Defender reports that it acted on the finding.
Channel: Microsoft-Windows-Windows Defender/Operational
Provider: Microsoft-Windows-Windows Defender
Event ids: 1007, 1117
Where to look next:
- Review Action Name and Error Code.
- Confirm whether the action cleaned, quarantined, removed, or allowed the item.
Related reasons:
av_threat_detected: detection that usually precedes the remediation recordav_threat_not_remediated: Allow action means no remediation was appliedav_threat_remediation_failed: remediation attempt failed
Fields it can set: win.defender.eventlog.action_id, win.defender.eventlog.action_name, win.defender.eventlog.process_name, win.defender.eventlog.status, win.defender.eventlog.threat_name, win.defender.eventlog.threat_path, win.defender.eventlog.user
av_threat_remediation_failed
Microsoft Defender tried to remediate a detected threat and failed.
Severity: Error
Impact: The detected threat may remain on disk or active because the cleanup action did not complete.
Channel: Microsoft-Windows-Windows Defender/Operational
Provider: Microsoft-Windows-Windows Defender
Event ids: 1008, 1118, 1119
Where to look next:
- Review Error Code and the affected Path.
- Run follow-up scan or manual cleanup if the threat is still present.
Related reasons:
av_threat_detected: detection that usually precedes the failureav_threat_not_remediated: item was allowed rather than remediatedav_threat_remediated: successful remediation outcome
Fields it can set: win.defender.eventlog.status, win.defender.eventlog.threat_name, win.defender.eventlog.threat_path
defender_asr_block
Microsoft Defender Attack Surface Reduction blocked an operation.
Severity: Warning
Impact: A configured ASR rule prevented behavior that policy considers risky or unwanted.
Channel: Microsoft-Windows-Windows Defender/Operational
Provider: Microsoft-Windows-Windows Defender
Event ids: 1121
Where to look next:
- Review rule ID, Path, and Process Name.
- Distinguish enforce-mode blocks from audit-mode would-block records.
Related reasons:
av_suspicious_behavior_detected: behavior-monitoring signal without an ASR rule blockdefender_network_protection_block: network protection block family
Fields it can set: win.defender.eventlog.process_name, win.defender.eventlog.rule_id, win.defender.eventlog.threat_path
defender_network_protection_block
Microsoft Defender Network Protection blocked a connection.
Severity: Warning
Impact: A configured protection policy prevented access to a network destination considered risky.
Channel: Microsoft-Windows-Windows Defender/Operational
Provider: Microsoft-Windows-Windows Defender
Event ids: 1126
Where to look next:
- Separate block-mode 1126 from audit-mode 1125.
- Review destination details when present in the rendered event.
Related reasons:
av_suspicious_behavior_detected: behavior monitoring found suspicious activitydefender_asr_block: another Defender policy-enforcement block
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