Detection rules › Splunk
UAC Bypass MMC Load Unsigned Dll
The following analytic detects the loading of an unsigned DLL by the MMC.exe application, which is indicative of a potential UAC bypass or privilege escalation attempt. It leverages Sysmon EventCode 7 to identify instances where MMC.exe loads a non-Microsoft, unsigned DLL. This activity is significant because attackers often use this technique to modify CLSID registry entries, causing MMC.exe to load malicious DLLs, thereby bypassing User Account Control (UAC) and gaining elevated privileges. If confirmed malicious, this could allow an attacker to execute arbitrary code with higher privileges, leading to further system compromise and persistence.
MITRE ATT&CK coverage
| Tactic | Techniques |
|---|---|
| Privilege Escalation | T1548.002 Abuse Elevation Control Mechanism: Bypass User Account Control |
| Defense Evasion | T1218.014 System Binary Proxy Execution: MMC, T1548.002 Abuse Elevation Control Mechanism: Bypass User Account Control |
Event coverage
| Provider | Event ID | Title |
|---|---|---|
| Sysmon | 7 | Image loaded |
Stages and Predicates
Stage 1: search
search Company!="Microsoft Corporation" EventCode=7 Image="*\\mmc.exe" ImageLoaded="*.dll" Signed=false
Stage 2: fillnull
fillnull
Stage 3: stats
stats BY Image, ImageLoaded, dest, loaded_file, loaded_file_path, original_file_name, process_exec, process_guid, process_hash, process_id, process_name, process_path, service_dll_signature_exists, service_dll_signature_verified, signature, signature_id, user_id, vendor_product
Stage 4: search
search
Stage 5: search
search
Stage 6: search
search `macro`
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 |
|---|---|---|
Company | ne |
|
EventCode | eq |
|
Image | eq |
|
ImageLoaded | eq |
|
Signed | eq |
|
Neighbors
Broader alternatives (more inclusive than this rule)
These rules match a superset of what this rule catches. They cover the same events plus more. Use them if you want wider coverage and can absorb more false positives.
- Windows Remote Access Software BRC4 Loaded Dll (drops 4 filters this rule applies)