Suspicious Regsvr32 Activity

• Detect Regsvr32 Application Control Bypass :
  endpoint Endpoint risk_score:80 2024-11-28 version:6
  The following analytic identifies the abuse of Regsvr32.exe to proxy execution of malicious code, specifically detecting the loading of "scrobj.dll" by Regsvr32.exe. This detection leverages data from Endpoint Detection and Response (EDR) agents, focusing on process creation events and command-line executions. This activity is significant because Regsvr32.exe is a trusted, signed Microsoft binary, often used in "Squiblydoo" attacks to bypass application control mechanisms. If confirmed malicious, this technique could allow an attacker to execute arbitrary code, potentially leading to system compromise and persistent access.


• Malicious InProcServer32 Modification :
  endpoint Endpoint risk_score:80 2024-09-30 version:4
  The following analytic detects a process modifying the registry with a known malicious CLSID under InProcServer32. It leverages data from Endpoint Detection and Response (EDR) agents, focusing on registry modifications within the HKLM or HKCU Software Classes CLSID paths. This activity is significant as it may indicate an attempt to load a malicious DLL, potentially leading to code execution. If confirmed malicious, this could allow an attacker to persist in the environment, execute arbitrary code, or escalate privileges, posing a severe threat to system integrity and security.


• Suspicious Regsvr32 Register Suspicious Path :
  endpoint Endpoint risk_score:35 2024-09-30 version:6
  The following analytic detects the use of Regsvr32.exe to register DLLs from suspicious paths such as AppData, ProgramData, or Windows Temp directories. It leverages data from Endpoint Detection and Response (EDR) agents, focusing on process execution logs and command-line arguments. This activity is significant because Regsvr32.exe can be abused to proxy execution of malicious code, bypassing traditional security controls. If confirmed malicious, this could allow an attacker to execute arbitrary code, potentially leading to system compromise, data exfiltration, or further lateral movement within the network.


• Regsvr32 with Known Silent Switch Cmdline :
  endpoint Endpoint risk_score:56 2024-09-30 version:5
  The following analytic detects the execution of Regsvr32.exe with the silent switch to load DLLs. This behavior is identified using Endpoint Detection and Response (EDR) telemetry, focusing on command-line executions containing the `-s` or `/s` switches. This activity is significant as it is commonly used in malware campaigns, such as IcedID, to stealthily load malicious DLLs. If confirmed malicious, this could allow an attacker to execute arbitrary code, download additional payloads, and potentially compromise the system further. Immediate investigation and endpoint isolation are recommended.


• Regsvr32 Silent and Install Param Dll Loading :
  endpoint Endpoint risk_score:36 2024-09-30 version:4
  The following analytic detects the loading of a DLL using the regsvr32 application with the silent parameter and DLLInstall execution. It leverages data from Endpoint Detection and Response (EDR) agents, focusing on process command-line arguments and parent process details. This activity is significant as it is commonly used by RAT malware like Remcos and njRAT to load malicious DLLs on compromised machines. If confirmed malicious, this technique could allow attackers to execute arbitrary code, maintain persistence, and further compromise the system.