Find sigma rule 
Attack: Event Triggered Execution: AppCert DLLs
Adversaries may establish persistence and/or elevate privileges by executing malicious content triggered by AppCert DLLs loaded into processes. Dynamic-link libraries (DLLs) that are specified in the AppCertDLLs Registry key under HKEY_LOCAL_MACHINE\System\CurrentControlSet\Control\Session Manager\ are loaded into every process that calls the ubiquitously used application programming interface (API) functions CreateProcess, CreateProcessAsUser, CreateProcessWithLoginW, CreateProcessWithTokenW, or WinExec. (Citation: Elastic Process Injection July 2017)
Similar to Process Injection, this value can be abused to obtain elevated privileges by causing a malicious DLL to be loaded and run in the context of separate processes on the computer. Malicious AppCert DLLs may also provide persistence by continuously being triggered by API activity.
MITRE
Tactic
- privilege-escalation
- persistence
technique
- T1546.009
Test : Create registry persistence via AppCert DLL
OS
- windows
Description:
Creates a new ‘AtomicTest’ value pointing to an AppCert DLL in the AppCertDlls registry key. Once the computer restarted, the DLL will be loaded in multiple processes and write an ‘AtomicTest.txt’ file in C:\Users\Public\ to validate that the DLL executed succesfully.
Reference: https://skanthak.homepage.t-online.de/appcert.html
Executor
powershell
Sigma Rule
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proc_creation_win_powershell_non_interactive_execution.yml (id: f4bbd493-b796-416e-bbf2-121235348529)
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file_event_win_shell_write_susp_directory.yml (id: 1277f594-a7d1-4f28-a2d3-73af5cbeab43)
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registry_set_asep_reg_keys_modification_session_manager.yml (id: 046218bd-e0d8-4113-a3c3-895a12b2b298)