ID | Technique | Tactic |
---|---|---|
T1574.002 | DLL Side-Loading | Defense Evasion |
T1547 | Boot or Logon Autostart Execution | Persistence |
Detection: Windows Unsigned MS DLL Side-Loading
Description
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.
Search
1`sysmon` EventCode=7 Company="Microsoft Corporation" Signed=false SignatureStatus != Valid NOT (Image IN("C:\\Windows\\System32\\*", "C:\\Windows\\SysWow64\\*", "C:\\Program Files*")) NOT (ImageLoaded IN("C:\\Windows\\System32\\*", "C:\\Windows\\SysWow64\\*", "C:\\Program Files*"))
2| rex field=Image "(?<ImageFolderPath>.+\\\)"
3| rex field=ImageLoaded "(?<ImageLoadedFolderPath>.+\\\)"
4| where ImageFolderPath = ImageLoadedFolderPath
5| stats count min(_time) as firstTime max(_time) as lastTime by Image ProcessGuid ImageLoaded user Computer EventCode ImageFolderPath ImageLoadedFolderPath Company Description Product Signed SignatureStatus
6| rename Computer as dest
7| `security_content_ctime(firstTime)`
8| `security_content_ctime(lastTime)`
9| `windows_unsigned_ms_dll_side_loading_filter`
Data Source
Name | Platform | Sourcetype | Source | Supported App |
---|---|---|---|---|
Sysmon EventID 7 | Windows | 'xmlwineventlog' |
'XmlWinEventLog:Microsoft-Windows-Sysmon/Operational' |
N/A |
Macros Used
Name | Value |
---|---|
security_content_ctime | convert timeformat="%Y-%m-%dT%H:%M:%S" ctime($field$) |
windows_unsigned_ms_dll_side_loading_filter | search * |
windows_unsigned_ms_dll_side_loading_filter
is an empty macro by default. It allows the user to filter out any results (false positives) without editing the SPL.
Annotations
Default Configuration
This detection is configured by default in Splunk Enterprise Security to run with the following settings:
Setting | Value |
---|---|
Disabled | true |
Cron Schedule | 0 * * * * |
Earliest Time | -70m@m |
Latest Time | -10m@m |
Schedule Window | auto |
Creates Risk Event | True |
Implementation
The analytic is designed to be run against Sysmon event logs collected from endpoints. The analytic requires the Sysmon event logs to be ingested into Splunk. The analytic searches for EventCode 7 where the Image is either SQLDumper.exe or SQLWriter.exe and the ImageLoaded is vcruntime140.dll. The search also filters out the legitimate loading of vcruntime140.dll from the System32 directory to reduce false positives. The analytic can be modified to include additional known good paths for vcruntime140.dll to further reduce false positives.
Known False Positives
False positives are possible if legitimate processes are loading vcruntime140.dll from non-standard directories. It is recommended to investigate the context of the process loading vcruntime140.dll to determine if it is malicious or not. Modify the search to include additional known good paths for vcruntime140.dll to reduce false positives.
Associated Analytic Story
Risk Based Analytics (RBA)
Risk Message | Risk Score | Impact | Confidence |
---|---|---|---|
An instance of $Image$ loading Unsigned $ImageLoaded$ was detected on $dest$. | 9 | 30 | 30 |
References
-
https://www.mandiant.com/resources/blog/apt29-wineloader-german-political-parties
-
https://www.zscaler.com/blogs/security-research/european-diplomats-targeted-spikedwine-wineloader
Detection Testing
Test Type | Status | Dataset | Source | Sourcetype |
---|---|---|---|---|
Validation | ✅ Passing | N/A | N/A | N/A |
Unit | ✅ Passing | Dataset | XmlWinEventLog:Microsoft-Windows-Sysmon/Operational |
xmlwineventlog |
Integration | ✅ Passing | Dataset | XmlWinEventLog:Microsoft-Windows-Sysmon/Operational |
xmlwineventlog |
Replay any dataset to Splunk Enterprise by using our replay.py
tool or the UI.
Alternatively you can replay a dataset into a Splunk Attack Range
Source: GitHub | Version: 2