T1574.012: COR_PROFILER
Adversaries may leverage the COR_PROFILER environment variable to hijack the execution flow of programs that load the .NET CLR. The COR_PROFILER is a .NET Framework feature which allows developers to specify an unmanaged (or external of .NET) profiling DLL to be loaded into each .NET process that loads the Common Language Runtime (CLR). These profilers are designed to monitor, troubleshoot, and debug managed code executed by the .NET CLR.[1][2]
The COR_PROFILER environment variable can be set at various scopes (system, user, or process) resulting in different levels of influence. System and user-wide environment variable scopes are specified in the Registry, where a Component Object Model (COM) object can be registered as a profiler DLL. A process scope COR_PROFILER can also be created in-memory without modifying the Registry. Starting with .NET Framework 4, the profiling DLL does not need to be registered as long as the location of the DLL is specified in the COR_PROFILER_PATH environment variable.[2]
Adversaries may abuse COR_PROFILER to establish persistence that executes a malicious DLL in the context of all .NET processes every time the CLR is invoked. The COR_PROFILER can also be used to elevate privileges (ex: Bypass User Account Control) if the victim .NET process executes at a higher permission level, as well as to hook and impair defenses provided by .NET processes.[3][4][5][6][7]
Analyst context for executives and security teams
COR_PROFILER abuse matters because a Windows .NET feature intended for profiling and debugging can be turned into an execution hijack point. If an attacker can set profiler-related environment variables or supporting registry/COM configuration, a DLL may load whenever .NET CLR processes start, creating persistence, stealthy execution, or execution in a higher-privileged .NET process context.
Executive priority
Treat this as a Windows endpoint and identity-control validation issue, not only a malware signature problem. Leaders should ask whether privileged accounts can modify relevant environment-variable or registry locations, whether application control limits unapproved DLL execution, and whether SOC telemetry can show profiler configuration changes and unexpected DLL loads in .NET processes. This is also useful audit evidence for least privilege, registry permission governance, and execution-prevention control maturity.
Technical view
For SOC, detection engineering, and IR teams, validate coverage around Windows systems that run .NET Framework applications. ATT&CK provides no official detection text for this sub-technique, but relationship context includes DET0479 for detecting hijack execution flow using Windows COR_PROFILER. Practical validation should focus on changes to system/user COR_PROFILER-related environment variables, registry-backed environment settings, COM profiler registration, COR_PROFILER_PATH usage, and unexpected unmanaged DLL loads into .NET CLR processes. Because process-scoped COR_PROFILER can exist in memory without registry modification, registry monitoring alone is insufficient.
Likely telemetry
- Windows registry modification events for user-wide and system-wide environment variables and COM profiler-related configuration
- Process creation telemetry that includes command line, parent process, integrity context, and environment variables where available
- Module/DLL load telemetry for .NET CLR processes, especially unmanaged profiler DLLs loaded from unusual paths
- File creation or modification telemetry for DLLs referenced by COR_PROFILER_PATH or profiler registration
- Account and privilege-change evidence relevant to users or processes able to modify registry/environment settings
Detection direction
- Use DET0479 as the ATT&CK-linked detection strategy reference, then test it against local Windows and .NET telemetry sources.
- Alert on new or modified COR_PROFILER and COR_PROFILER_PATH values at system, user, or process scope where observable.
- Correlate profiler configuration with subsequent .NET process starts and DLL loads; the useful signal is often the combination of configuration change plus unexpected module load.
- Baseline legitimate developer, monitoring, troubleshooting, or profiling tools to reduce false positives; COR_PROFILER is a legitimate .NET Framework feature.
- Do not rely only on registry auditing because ATT&CK notes process-scoped COR_PROFILER can be created in memory without registry changes.
Mitigation priorities
- Prioritize User Account Management: enforce least privilege so ordinary users and service accounts cannot broadly modify sensitive environment-variable or registry locations.
- Restrict registry permissions on keys used for system/user environment variables and COM-related profiler registration so only authorized administrators or management tooling can change them.
- Use execution prevention controls to limit unauthorized DLL execution, especially profiler DLLs from untrusted or user-writable paths.
- Maintain an approved inventory of legitimate .NET profilers and troubleshooting tools so defenders can distinguish expected engineering activity from suspicious persistence.
- Include COR_PROFILER checks in Windows endpoint hardening, incident response triage, and compliance evidence for privileged access, registry control, and application control.
Analyst notes and limits
ATT&CK classifies this as a Windows sub-technique under Hijack Execution Flow with stealth and execution tactics. Relationship context states Blue Mockingbird and DarkTortilla use this technique, and mitigations M1018, M1024, and M1038 apply. These relationships support defensive prioritization, but they do not by themselves prove current activity in any specific environment.
The official ATT&CK object does not provide detection text, so detection guidance is derived from the technique description, external references listed by ATT&CK, and the DET0479 relationship. Local validation is required to know whether process environment variables, module loads, registry changes, and application-control decisions are actually collected and retained.
COR_PROFILER
Adversaries may leverage the COR_PROFILER environment variable to hijack the execution flow of programs that load the .NET CLR. The COR_PROFILER is a .NET Framework feature which allows developers to specify an unmanaged (or external of .NET) profiling DLL to be loaded into each .NET process that loads the Common Language Runtime (CLR). These profilers are designed to monitor, troubleshoot, and debug managed code executed by the .NET CLR.[1][2]
The COR_PROFILER environment variable can be set at various scopes (system, user, or process) resulting in different levels of influence. System and user-wide environment variable scopes are specified in the Registry, where a Component Object Model (COM) object can be registered as a profiler DLL. A process scope COR_PROFILER can also be created in-memory without modifying the Registry. Starting with .NET Framework 4, the profiling DLL does not need to be registered as long as the location of the DLL is specified in the COR_PROFILER_PATH environment variable.[2]
Adversaries may abuse COR_PROFILER to establish persistence that executes a malicious DLL in the context of all .NET processes every time the CLR is invoked. The COR_PROFILER can also be used to elevate privileges (ex: Bypass User Account Control) if the victim .NET process executes at a higher permission level, as well as to hook and impair defenses provided by .NET processes.[3][4][5][6][7]
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.
Related techniques
This mirrors the MITRE pattern of making group, software, campaign, and technique relationships scannable. Relationship notes come from mirrored ATT&CK relationship text when available.
| Domain | ID | Name | Relationship / procedure |
|---|---|---|---|
| Enterprise | T1574 | Hijack Execution Flow | This object subtechnique of Hijack Execution Flow. |
Groups, software, and campaigns
G0108: Blue Mockingbird
Blue Mockingbird is a cluster of observed activity involving Monero cryptocurrency-mining payloads in dynamic-link library (DLL) form on Windows systems. The earliest observed Blue Mockingbird tools were created in December 2019.[1]
S1066: DarkTortilla
DarkTortilla is a highly configurable .NET-based crypter that has been possibly active since at least August 2015. DarkTortilla has been used to deliver popular information stealers, RATs, and payloads such as Agent Tesla, AsyncRat, NanoCore, RedLine, Cobalt Strike, and Metasploit.[1]
All related ATT&CK context
Mitigation direction
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 | 2.0 | Current bundle | 6f37870bdfb9… |
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.
-
[1]
Microsoft Profiling Mar 2017
Microsoft. (2017, March 30). Profiling Overview. Retrieved June 24, 2020.
Open source URL -
[2]
Microsoft COR_PROFILER Feb 2013
Microsoft. (2013, February 4). Registry-Free Profiler Startup and Attach. Retrieved June 24, 2020.
Open source URL -
[3]
RedCanary Mockingbird May 2020
Lambert, T. (2020, May 7). Introducing Blue Mockingbird. Retrieved May 26, 2020.
Open source URL -
[4]
Red Canary COR_PROFILER May 2020
Brown, J. (2020, May 7). Detecting COR_PROFILER manipulation for persistence. Retrieved June 24, 2020.
Open source URL -
[5]
Almond COR_PROFILER Apr 2019
Almond. (2019, April 30). UAC bypass via elevated .NET applications. Retrieved June 24, 2020.
Open source URL -
[6]
GitHub OmerYa Invisi-Shell
Yair, O. (2019, August 19). Invisi-Shell. Retrieved June 24, 2020.
Open source URL -
[7]
subTee .NET Profilers May 2017
Smith, C. (2017, May 18). Subvert CLR Process Listing With .NET Profilers. Retrieved June 24, 2020.
Open source URL -
[8]
mitre-attack T1574.012Open source URL
Source: MITRE ATT&CK®. © 2026 The MITRE Corporation. This work is reproduced and distributed with the permission of The MITRE Corporation. MITRE ATT&CK and ATT&CK are registered trademarks of The MITRE Corporation. Glexia is not affiliated with or endorsed by MITRE.