AppCert DLLs
Where this stands
One published detection covers this technique. Every one is unverified — no rule on Siemphony has been executed against real telemetry.
What the technique is
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. 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.
Read it on attack.mitre.orgWhat MITRE says you would watch
- AN1029
Detection of AppCert DLL abuse involves correlating registry modifications to the AppCertDLLs key with subsequent unexpected DLL load behavior during process creation events. Specifically, defenders can observe abnormal DLLs being loaded into standard Windows processes after changes to the 'AppCertDLLs' registry value. Monitoring CreateProcess-family API executions with injected DLLs and linking those DLLs back to recent registry edits is key to identifying misuse. This is often accompanied by elevated privileges and potential lateral movement or discovery behavior.
Technique names and descriptions © MITRE ATT&CK®, CC BY 4.0. Not endorsed by MITRE.