Detection rules › Sigma
Potential AMSI COM Server Hijacking
Detects changes to the AMSI come server registry key in order disable AMSI scanning functionalities. When AMSI attempts to starts its COM component, it will query its registered CLSID and return a non-existent COM server. This causes a load failure and prevents any scanning methods from being accessed, ultimately rendering AMSI useless
MITRE ATT&CK coverage
| Tactic | Techniques |
|---|---|
| Defense Evasion | T1562.001 Impair Defenses: Disable or Modify Tools |
Event coverage
| Provider | Event ID | Title |
|---|---|---|
| Sysmon | 13 | RegistryEvent (Value Set) |
Stages and Predicates
Stage 1: selection
TargetObject|endswith: '\CLSID\{fdb00e52-a214-4aa1-8fba-4357bb0072ec}\InProcServer32\(Default)'
Stage 2: not filter
Details: '%windir%\system32\amsi.dll'
Indicators
Each row is a field, operator, and value that the rule matches. The corpus column counts how many other rules in the catalog look for the same combination: high numbers point to widely-used, community-vetted indicators. Blank or 1 shows that the indicator is specific to this rule.
| Field | Kind | Values |
|---|---|---|
Details | eq |
|
TargetObject | ends_with |
|