>coregen.exe
Binary coregen.exe (Microsoft CoreCLR Native Image Generator) loads exported function GetCLRRuntimeHost from coreclr.dll or from .DLL in arbitrary path. Coregen is located within "C:\Program Files (x86)\Microsoft Silverlight\5.1.50918.0\" or another version of Silverlight. Coregen is signed by Microsoft and bundled with Microsoft Silverlight.
Default Executable Paths
C:\Program Files\Microsoft Silverlight\5.1.50918.0\coregen.exeC:\Program Files (x86)\Microsoft Silverlight\5.1.50918.0\coregen.exeIntegrity & Metadata
Documented in LOLBAS project by Martin Sohn Christensen.
Monitor process creation events where FileName is "coregen.exe" or command line references known attack arguments.
Executive Summary & AI Quick Reference
coregen.exe is a native utility pre-installed on Windows systems. Threat actors and red teams abuse coregen.exe as a Living-off-the-Land Binary (LOLBin) to achieve Execute, Defense Evasion without triggering traditional antivirus file-hash alerts. Legitimate system administrators use it for routine administration, making behavioral command-line telemetry essential for differentiation.
Weaponized Parameters & Proof-of-Concepts
Documented attack commands, parameter flags, and privilege prerequisites.
Loads the target .DLL in arbitrary path specified with /L.
coregen.exe /L {PATH_ABSOLUTE:.dll} dummy_assembly_nameLoads the coreclr.dll in the corgen.exe directory (e.g. C:\Program Files\Microsoft Silverlight\5.1.50918.0).
coregen.exe dummy_assembly_nameLoads the target .DLL in arbitrary path specified with /L. Since binary is signed it can also be used to bypass application whitelisting solutions.
coregen.exe /L {PATH_ABSOLUTE:.dll} dummy_assembly_nameSIEM & EDR Detection Rules
Production telemetry rules configured for Microsoft Defender, Sigma, and Splunk.
Telemetry & SIEM Detection Suite (coregen.exe)
Validated against MITRE T1055, T12181// Microsoft Defender XDR / Microsoft Sentinel2// Tactic: Execute3DeviceProcessEvents4| where FileName =~ "coregen.exe"5| where ProcessCommandLine has_any ("coregen")6| project7 Timestamp,8 DeviceName,9 AccountName,10 InitiatingProcessParentFileName,11 InitiatingProcessFileName,12 InitiatingProcessCommandLine,13 FileName,14 FolderPath,15 ProcessCommandLine,16 MD5,17 SHA25618| sort by Timestamp descMitigation, Hardening & Prevention
Recommended defensive controls to block or constrain coregen.exe abuse.
Enforce Windows Defender Application Control (WDAC) or AppLocker publisher rules to prevent execution outside approved enterprise administration scripts.
Enable ASR rules: Block executable content from email client and webmail and Block Office applications from creating child processes spawning coregen.exe.
Deploy the KQL, Sigma, and Splunk detection queries below. Alert on anomalous child processes, web requests to unrated external IPs, or encoded payload strings.
Frequently Asked Questions (FAQ) • coregen.exe
Key operational questions and defensive answers about coregen.exe LOLBin tradecraft.
What is coregen.exe and why is it classified as a LOLBin?
coregen.exe is a legitimate, pre-installed or trusted utility on Windows. It is classified as a Living-off-the-Land Binary (LOLBin) because adversaries abuse its built-in functionality to perform malicious operations—such as Execute, Defense Evasion—without dropping custom malware binaries on disk.
How do threat actors abuse coregen.exe in cyber intrusions?
Adversaries leverage coregen.exe to execute stealthy actions while evading signature-based security controls. For example, attackers execute commands like "coregen.exe /L {PATH_ABSOLUTE:.dll} dummy_assembly_name" to achieve Execute, Defense Evasion, masquerading behind legitimate system process lineage.
How can SOC analysts detect suspicious coregen.exe activity?
Detection engineers monitor process creation events (Windows Event ID 4688 or Sysmon Event ID 1; Linux auditd EXECVE; macOS Endpoint Security) inspecting anomalous command line arguments, unusual parent-child process relationships (e.g. Office apps or web servers spawning coregen.exe), and unexpected network connections.
What MITRE ATT&CK techniques does coregen.exe map to?
coregen.exe maps to MITRE ATT&CK technique(s): T1055, T1218. These techniques cover adversary actions across tactics such as Defense Evasion, Execution, Persistence, and Command and Control.
How can organizations mitigate and restrict coregen.exe?
Mitigation strategies include implementing Application Control policies (AppLocker or Windows Defender Application Control - WDAC), enforcing Attack Surface Reduction (ASR) rules, configuring strict privilege separation (disallowing standard users from running sensitive switches), and alerting on execution from non-standard directories.
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