AN1536: Analytic 1536
Registry key modification to AppInit_DLLs value followed by anomalous DLL loading by processes importing user32.dll, especially unsigned or uncommon DLLs, suggesting unauthorized AppInit persistence or privilege escalation.
Analyst context for executives and security teams
AN1536 is a Windows detection analytic focused on changes to the AppInit_DLLs registry value followed by unusual DLL loading in processes that import user32.dll. For security leaders, the value is that this behavior can indicate persistence or privilege escalation through a Windows mechanism that may be missed if teams only monitor process execution and not registry-to-module-load sequences.
Executive priority
Prioritize this as a Windows endpoint resilience and incident readiness question: can the organization prove when AppInit_DLLs is modified, identify which process later loads the DLL, and distinguish expected administrative or software behavior from suspicious unsigned or uncommon DLLs? This supports control validation, audit evidence for endpoint monitoring, and faster incident triage when persistence is suspected.
Technical view
SOC and detection teams should validate whether Windows telemetry can correlate registry modification of the AppInit_DLLs value with subsequent DLL load activity by processes importing user32.dll. Because ATT&CK provides no official detection logic or relationship context for this analytic, implementation should focus on the behavior described: registry value modification, DLL load events, DLL signing status, DLL prevalence or commonality, and process context. IR teams should be prepared to review the modified registry value, the DLL path, signer status, parent process context, and whether the loading process is expected to import user32.dll.
Likely telemetry
- Windows registry modification events for AppInit_DLLs
- Windows module or DLL load telemetry
- Process execution and parent-child process context
- File metadata for loaded DLLs, including path, hash, and signer status
- Endpoint inventory or prevalence data to determine whether a DLL is uncommon
Detection direction
- Correlate AppInit_DLLs registry changes with later DLL loads rather than alerting on either signal alone.
- Tune for unsigned, uncommon, or unexpected DLLs loaded by processes importing user32.dll, as described in the analytic.
- Account for legitimate software or administrative changes that may use AppInit_DLLs to reduce false positives.
- Validate telemetry coverage on Windows endpoints; the analytic does not specify tactics, relationships, or official detection logic.
- Ensure alert output preserves registry value data, DLL path, process identity, and signer/prevalence context for triage.
Mitigation priorities
- Harden and monitor write access to relevant Windows registry locations associated with AppInit_DLLs.
- Maintain endpoint logging capable of capturing registry changes and DLL load activity.
- Use application control, code-signing policy, or allowlisting approaches where appropriate to reduce unauthorized DLL loading risk.
- Create IR procedures for reviewing suspicious AppInit_DLLs values and associated DLLs.
- Periodically test whether SOC tooling can detect the described registry-to-DLL-load sequence on Windows systems.
Analyst notes and limits
This take is based only on the supplied ATT&CK analytic description. The object is a detection analytic for Windows and does not include ATT&CK tactics, linked techniques, relationships, or official detection pseudocode. The strongest defensive value comes from validating telemetry correlation between registry modification and subsequent anomalous DLL loading.
No relationship context, tactic mapping, or official detection field was supplied. Local baselines are required to determine which DLLs are truly uncommon or unauthorized, and the presence of this behavior alone should not be treated as confirmed compromise without endpoint context.
Analytic 1536
Registry key modification to AppInit_DLLs value followed by anomalous DLL loading by processes importing user32.dll, especially unsigned or uncommon DLLs, suggesting unauthorized AppInit persistence or privilege escalation.
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 | db654b2d0675… |
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 AN1536Open source URL
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