Detection rules › Splunk
Msmpeng Application DLL Side Loading
The following analytic detects the suspicious creation of msmpeng.exe or mpsvc.dll in non-default Windows Defender folders. It leverages the Endpoint.Filesystem datamodel to identify instances where these files are created outside their expected directories. This activity is significant because it is associated with the REvil ransomware, which uses DLL side-loading to execute malicious payloads. If confirmed malicious, this could lead to ransomware deployment, resulting in data encryption, system compromise, and potential data loss or extortion.
MITRE ATT&CK coverage
| Tactic | Techniques |
|---|---|
| Persistence | T1574.001 Hijack Execution Flow: DLL |
| Privilege Escalation | T1574.001 Hijack Execution Flow: DLL |
| Defense Evasion | T1574.001 Hijack Execution Flow: DLL |
Event coverage
| Provider | Event ID | Title |
|---|---|---|
| Sysmon | 11 | FileCreate |
Stages and Predicates
Stage 1: tstats
tstats WHERE (Filesystem.file_name="mpsvc.dll" OR Filesystem.file_name="msmpeng.exe") NOT Filesystem.file_path IN ("*\\Program Files\\windows defender\\*", "*\\WinSxS\\*defender-service*", "*\\WinSxS\\Temp\\*defender-service*") BY Filesystem.action, Filesystem.dest, Filesystem.file_access_time, Filesystem.file_create_time, Filesystem.file_hash, Filesystem.file_modify_time, Filesystem.file_name, Filesystem.file_path, Filesystem.file_acl, Filesystem.file_size, Filesystem.process_guid, Filesystem.process_id, Filesystem.user, Filesystem.vendor_product
Stage 2: search
search
Stage 3: search
search
Stage 4: search
search
Stage 5: search
search `macro`
Exclusions
Top-level NOT(...) conjuncts — predicates this rule actively suppresses.
| Stage | Field | Kind | Excluded values |
|---|---|---|---|
| 1 | TargetFilename | in | "*\\Program Files\\windows defender\\*", "*\\WinSxS\\*defender-service*", "*\\WinSxS\\Temp\\*defender-service*" |
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 |
|---|---|---|
Filesystem.file_name | eq |
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