Detection rules › Splunk
Windows Unsigned DLL Side-Loading
The following analytic detects the creation of potentially malicious unsigned DLLs in the c:\windows\system32 or c:\windows\syswow64 folders. It leverages Sysmon EventCode 7 logs to identify unsigned DLLs with unavailable signatures loaded in these critical directories. This activity is significant as it may indicate a DLL hijacking attempt, a technique used by attackers to gain unauthorized access and execute malicious code. If confirmed malicious, this could lead to privilege escalation, allowing the attacker to gain elevated privileges and further compromise the target system.
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 | 7 | Image loaded |
Stages and Predicates
Stage 1: search
search EventCode=7 ImageLoaded IN ("*:\\windows\\system32\\*", "*:\\windows\\syswow64\\*") OriginalFileName="-" SignatureStatus="unavailable" 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 |
|---|---|---|
EventCode | eq |
|
ImageLoaded | in |
|
OriginalFileName | eq |
|
SignatureStatus | 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)