ATT&CK coverage › Technique

Event Triggered Execution: AppCert DLLs T1546.009

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 <code>AppCertDLLs</code> Registry key under <code>HKEY_LOCAL_MACHINE\System\CurrentControlSet\Control\Session Manager\</code> are loaded into every process that calls the ubiquitously used application programming interface (API) functions <code>CreateProcess</code>, <code>CreateProcessAsUser</code>, <code>CreateProcessWithLoginW</code>, <code>CreateProcessWithTokenW</code>, or <code>WinExec</code>.

Events covered

3 catalog events are tagged with this technique by at least one rule.

ProviderEvent IDTitle
Sysmon12RegistryEvent (Object create and delete)
Sysmon13RegistryEvent (Value Set)
Sysmon14RegistryEvent (Key and Value Rename)

Authoring guide

Patterns shared across the 3 rules above: which fields they filter on, what specific values they look for, and what they exclude. Field names are normalized across vendors so Sigma's Image, Elastic's process.name, and Splunk's process_name collapse into one row. Each rule contributes at most once per row.

Fields filtered most (5 distinct)

The fields most rules look at when detecting this technique. The How column shows the operators authors use (eq, wildcard, regex_match, match) and how often each appears. Sample values are concrete examples to start from, not an exhaustive list.

FieldRulesHowSample values
TargetObject3match 2, eq 1\\Control\\Session Manager\\AppCertDLLs\\, HKLM\SYSTEM\CurrentControlSet\Control\Session Manager\AppCertDlls, \BootExecute, \System\CurrentControlSet\Control\Session Manager, \KnownDlls
EventLog1eq 1Microsoft-Windows-Sysmon/Operational
EventID1eq 113
NewName1eq 1HKLM\SYSTEM\CurentControlSet\Control\Session Manager\AppCertDlls
Details1eq 1(Empty)

Top indicator values (13 distinct)

Specific (field, operator, value) combinations the rules check for, ranked by how many rules under this technique use each one. The Corpus reach column counts how many rules across the entire catalog (any technique) check the same combination. High numbers point to widely-used indicators that are likely noisy on their own; combine them with another condition for useful signal. Blank means the combination is specific to rules under this technique.

FieldKindValueRules (here)Corpus reach
TargetObjectmatch\\Control\\Session Manager\\AppCertDLLs\\1
EventLogeqMicrosoft-Windows-Sysmon/Operational1
EventIDeq131
TargetObjecteqHKLM\SYSTEM\CurrentControlSet\Control\Session Manager\AppCertDlls1
NewNameeqHKLM\SYSTEM\CurentControlSet\Control\Session Manager\AppCertDlls1
TargetObjectmatch\Execute1
TargetObjectmatch\S0InitialCommand1
TargetObjectmatch\SetupExecute1
TargetObjectmatch\KnownDlls1
Detailseq(Empty)124
TargetObjectmatch\AppCertDlls1
TargetObjectmatch\System\CurrentControlSet\Control\Session Manager1
TargetObjectmatch\BootExecute1

Rules under this technique

Every rule in the catalog tagged with this technique, grouped by vendor. Click a rule title for its full predicates, exclusions, and indicators.

Sigma 2 rules

Kusto Query Language 1 rule