SOC Event Lookup
Event ID 255ServiceP3

Sysmon Event ID 255: Sysmon service error report

Applicable version
Sysmon with this event enabled
Last reviewed
2026-07-22

Quick summary

Sysmon Event ID 255 records an internal Sysmon error condition.

Technical Metadata

Technical metadata for Event ID 255
Event ID255
ProviderMicrosoft-Windows-Sysmon
ChannelMicrosoft-Windows-Sysmon/Operational
LevelInformational
MITRE ATT&CKTA0005 Defense Evasion / T1562.001 Impair Defenses: Disable or Modify Tools
Key fields to watchID / Description, UtcTime, Computer

Trigger Scenarios

Microsoft documents that this event is generated when an error occurs within Sysmon, including heavy load, tasks that could not be performed, a Sysmon service bug, or security and integrity conditions not being met.

Key Fields

ID / Description

The error identifier and description explain which Sysmon component failed. Microsoft Q&A examples include RuleEngine and ServiceThread descriptions for schema incompatibility.

UtcTime

Use the timestamp to measure telemetry gaps around the error.

Computer

Prioritize hosts where Sysmon errors affect critical telemetry coverage.

Threat Hunting Queries

Microsoft Sentinel KQL: Retrieve Sysmon Event ID 255
Event
| where EventLog == "Microsoft-Windows-Sysmon/Operational" and EventID == 255
| project TimeGenerated, Computer, EventID, RenderedDescription
| order by TimeGenerated desc
Data source
Microsoft Sentinel Event table
Assumptions
The Sysmon Operational channel is collected into Event. Map raw XML fields to the event-specific fields described on this page.
Query reference
Splunk SPL: Retrieve Sysmon Event ID 255
index=sysmon source="WinEventLog:Microsoft-Windows-Sysmon/Operational" EventCode=255
| table _time, host, EventCode, Message
Data source
Splunk Sysmon event data
Assumptions
Index, source, and parsed field names vary by deployment. Apply the documented field conditions after validating local field extraction.
Cortex XQL: Retrieve Sysmon Event ID 255
dataset = microsoft_windows_raw
| filter edr_event_id = 255
Data source
Cortex XDR microsoft_windows_raw
Assumptions
Confirm Provider is Microsoft-Windows-Sysmon because event IDs are not globally unique. Inspect raw provider fields because parsed names vary by collection path.
Query reference
Sigma rule: Sysmon Event ID 255
title: Sysmon Event ID 255
status: experimental
logsource:
    product: windows
    service: sysmon
detection:
    selection:
        EventID: 255
    condition: selection
falsepositives:
    - Legitimate administrative or system activity
level: informational
Data source
Sigma Windows Sysmon log source
Assumptions
This rule retrieves the event and is not a standalone malicious-behavior detection. Add the event-specific conditions and correlations documented on this page.
Query reference

Documented Values and Codes

Documented event values and their security relevance
FieldValueMeaningSecurity relevance
EventID255Sysmon reported an internal error.Interpret EventID with the other documented fields and correlated events; this value alone is not proof of compromise. Source
Descriptionerror textThe actual error description is required to distinguish load, bug, and integrity conditions.Interpret Description with the other documented fields and correlated events; this value alone is not proof of compromise. Source

MITRE ATT&CK Mapping

  • T1562.001Impair Defenses: Disable or Modify Tools

Detection Notes

Use threshold=1 on high-value hosts when Event 255 contains ID=DriverCommunication, RuleEngine, ServiceThread, or another error that creates a telemetry gap. Microsoft documents Event 255 for Sysmon internal errors and notes security/integrity conditions may be involved; treat it as T1562.001 only when it follows service stop, configuration change, driver unload, or unexplained loss of Events 1/3/11. Correlate with Events 4 and 16 and verify whether the Sysmon schema/configuration version changed before escalating.

Common False Positives

  • High system load and Sysmon bugs can generate this event without attacker activity.
  • Configuration schema mismatches after upgrades can produce RuleEngine or ServiceThread errors until the configuration is rebuilt.

Related Events

Sample Log

Sanitized event sample
UtcTime: 2026-07-13 03:08:00.000
ID: RuleEngine
Description: Registry rule version 4.22 is incompatible with Sysmon rule version 4.30
Computer: HOST01

Frequently Asked Questions

What does Sysmon Event ID 255 mean?

Sysmon encountered an internal error caused by load, a software defect, or a security or integrity condition.

Does Event ID 255 always indicate malicious activity?

No. Operational overload and product defects can generate it.

How should Event ID 255 be investigated?

Review the exact error description, Sysmon version, host load, configuration, and nearby Events 4 and 16.

Sources

Machine-readable JSON