AN0251: Analytic 0251
Installation or execution of a malicious browser or IDE extension, followed by abnormal registry entries or outbound network connections from the host application
Analyst context for executives and security teams
AN0251 is a Windows-focused detection analytic concept for spotting malicious browser or IDE extensions by looking for suspicious extension activity followed by unusual registry changes or outbound network connections from the host application. For leaders, the practical issue is that trusted productivity tools can become a monitoring blind spot: browsers and development environments often have network access, user context, and business-critical workflows, so extension governance and telemetry quality matter.
Executive priority
Prioritize this analytic where Windows endpoints, browsers, and IDEs are important to business operations or developer productivity. The decision value is to confirm whether the organization can prove which extensions are installed, detect abnormal registry activity, and investigate outbound connections made by trusted host applications. This supports incident response readiness, endpoint control assurance, audit evidence for software governance, and risk-based prioritization of monitoring around high-value user and developer workstations.
Technical view
Validate coverage on Windows for three linked evidence areas: extension installation or execution, abnormal registry entries, and outbound network connections from the browser or IDE host process. Because no official detection logic or ATT&CK relationships are supplied, teams should treat AN0251 as an analytic design prompt rather than a ready-to-run rule. SOC and detection engineering should baseline normal extension behavior by host application and user role, then alert on unusual registry modifications or external network activity temporally associated with extension installation or execution.
Likely telemetry
- Windows endpoint telemetry showing browser or IDE process execution and child or module activity where available
- Browser and IDE extension inventory, installation, enablement, or execution records
- Windows registry monitoring for new or abnormal entries associated with browser or IDE extension activity
- Outbound network connection telemetry from browser or IDE host applications, including destination, timing, and process context
- Endpoint detection and response records correlating process, registry, and network events on the same Windows host
Detection direction
- Confirm that telemetry can correlate extension installation or execution with subsequent registry and network activity on the same Windows endpoint.
- Baseline approved browser and IDE extensions, common registry changes, and expected outbound destinations to reduce false positives from legitimate extension updates or developer tooling.
- Tune for abnormal combinations rather than single events: a new or unexpected extension plus unusual registry entries plus outbound connections from the host application is more meaningful than any one signal alone.
- Review blind spots around unmanaged browsers, portable IDEs, limited registry auditing, encrypted outbound traffic visibility, and endpoints where extension inventories are not centrally collected.
- Because tactics and relationships are not supplied, map any local detections to the organization’s own incident categories and ATT&CK coverage model only after validation.
Mitigation priorities
- Establish and maintain an approved extension inventory for Windows browsers and IDEs used in the environment.
- Apply endpoint and application governance controls that restrict or review unapproved extensions where operationally feasible.
- Ensure registry and process-network telemetry is collected from Windows systems where browsers or IDEs handle sensitive workflows.
- Create incident response playbooks for suspicious extension findings, including host isolation decision points, extension removal, registry review, and outbound destination triage.
- Use detection results to support compliance evidence for software control, endpoint monitoring, and change governance.
Analyst notes and limits
The supplied ATT&CK object is a detection analytic, not a technique, and provides a short behavior description only. The strongest use is as a coverage-validation checklist for Windows endpoints running browsers or IDEs. Local baselines are essential because legitimate extensions and development tools may create registry entries and outbound connections.
No official detection logic, tactics, ATT&CK relationships, mitigations, data components, threat actors, campaigns, or active exploitation context were supplied. This take therefore avoids attribution and does not claim that any specific detection will work without local telemetry and tuning.
Analytic 0251
Installation or execution of a malicious browser or IDE extension, followed by abnormal registry entries or outbound network connections from the host application
How security teams should use this page
Treat this object as behavior context, not an attribution claim. Validate the related groups, software, data sources, and mitigations against official ATT&CK relationships and your own telemetry before making control-coverage decisions.
All related ATT&CK context
No relationships are available in the current normalized data for this object.
Object version and sync metadata
The fields below describe the current mirrored snapshot. When Glexia retains multiple ATT&CK source imports, you can open the table to compare the same object across releases (hashes and MITRE timestamps). For MITRE’s own release notes and roadmap, see ATT&CK resources — Updates .
Imported snapshots across ATT&CK releases (1)
| Release | Bundle imported | Object version | Modified | Status | Raw hash |
|---|---|---|---|---|---|
| 19.1 | 1.0 | Current bundle | c60ed12ee950… |
Mirrored ATT&CK source object
The raw object is retained through the mirrored ATT&CK source bundle and object hash. The raw endpoint returns the exact object from the mirrored bundle when available.
External references and citations
MITRE external references are preserved separately from Glexia analysis so citations remain traceable to their original source records.
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[1]
mitre-attack AN0251Open source URL
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