Detection rules › Splunk
Windows Unsigned MS DLL Side-Loading
The following analytic identifies potential DLL side-loading instances involving unsigned DLLs mimicking Microsoft signatures. It detects this activity by analyzing Sysmon logs for Event Code 7, where both the Image and ImageLoaded paths do not match system directories like system32, syswow64, and programfiles. This behavior is significant as adversaries often exploit DLL side-loading to execute malicious code via legitimate processes. If confirmed malicious, this activity could allow attackers to execute arbitrary code, potentially leading to privilege escalation, persistence, and unauthorized access to sensitive information.
MITRE ATT&CK coverage
| Tactic | Techniques |
|---|---|
| Persistence | T1547 Boot or Logon Autostart Execution, T1574.001 Hijack Execution Flow: DLL |
| Privilege Escalation | T1547 Boot or Logon Autostart Execution, T1574.001 Hijack Execution Flow: DLL |
| Defense Evasion | T1574.001 Hijack Execution Flow: DLL |
Event coverage
| Provider | Event ID | Title |
|---|---|---|
| Sysmon | 7 | Image loaded |
Stages and Predicates
Stage 1: search
search NOT (NOT ImageLoaded IN ("C:\\Program Files \(x86\)\\*", "C:\\Program Files\\*", "C:\\Windows\\SysWow64\\*", "C:\\Windows\\System32\\*") Image IN ("C:\\Program Files \(x86\)\\*", "C:\\Program Files\\*", "C:\\Windows\\SysWow64\\*", "C:\\Windows\\System32\\*")) Company="Microsoft Corporation" EventCode=7 SignatureStatus!="Valid" Signed=false
Stage 2: rex
rex field=Image ...
Stage 3: rex
rex field=ImageLoaded ...
Stage 4: where
where ImageFolderPath=
Stage 5: 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 6: search
search
Stage 7: search
search
Stage 8: search
search `macro`
Exclusions
Top-level NOT(...) conjuncts — predicates this rule actively suppresses.
| Stage | Field | Kind | Excluded values |
|---|---|---|---|
| 1 | ImageLoaded | in | "C:\\Program Files \(x86\)\\*", "C:\\Program Files\\*", "C:\\Windows\\SysWow64\\*", "C:\\Windows\\System32\\*" |
| 2 | Image | in | "C:\\Program Files \(x86\)\\*", "C:\\Program Files\\*", "C:\\Windows\\SysWow64\\*", "C:\\Windows\\System32\\*" |
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 | eq |
|
EventCode | eq |
|
ImageLoaded | in |
|
SignatureStatus | ne |
|
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)