Detection: Windows Input Capture Using Credential UI Dll

Description

The following analytic detects a process loading the credui.dll or wincredui.dll module. This detection leverages Sysmon EventCode 7 to identify instances where these DLLs are loaded by processes outside typical system directories. This activity is significant because adversaries often abuse these modules to create fake credential prompts or dump credentials, posing a risk of credential theft. If confirmed malicious, this activity could allow attackers to harvest user credentials, leading to unauthorized access and potential lateral movement within the network.

1`sysmon` EventCode=7  (ImageLoaded = "*\\credui.dll" AND OriginalFileName = "credui.dll") OR (ImageLoaded = "*\\wincredui.dll" AND OriginalFileName = "wincredui.dll") AND NOT(Image IN("*\\windows\\explorer.exe", "*\\windows\\system32\\*", "*\\windows\\sysWow64\\*", "*:\\program files*")) 
2| stats count min(_time) as firstTime max(_time) as lastTime by Image ImageLoaded OriginalFileName dest EventCode Signed ProcessId ProcessGuid 
3| `security_content_ctime(firstTime)` 
4| `security_content_ctime(lastTime)` 
5| `windows_input_capture_using_credential_ui_dll_filter`

Data Source

Name Platform Sourcetype Source
Sysmon EventID 7 Windows icon Windows 'xmlwineventlog' 'XmlWinEventLog:Microsoft-Windows-Sysmon/Operational'

Macros Used

Name Value
security_content_ctime convert timeformat="%Y-%m-%dT%H:%M:%S" ctime($field$)
windows_input_capture_using_credential_ui_dll_filter search *
windows_input_capture_using_credential_ui_dll_filter is an empty macro by default. It allows the user to filter out any results (false positives) without editing the SPL.

Annotations

- MITRE ATT&CK
+ Kill Chain Phases
+ NIST
+ CIS
- Threat Actors
ID Technique Tactic
T1056.002 GUI Input Capture Collection
T1056 Input Capture Credential Access
KillChainPhase.EXPLOITAITON
NistCategory.DE_AE
Cis18Value.CIS_10
FIN4
RedCurl
APT39

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 False
This configuration file applies to all detections of type hunting.

Implementation

The latest Sysmon TA 3.0 https://splunkbase.splunk.com/app/5709 will add the ImageLoaded name to the process_name field, allowing this query to work. Use as an example and implement for other products.

Known False Positives

this module can be loaded by a third party application. Filter is needed.

Associated Analytic Story

Risk Based Analytics (RBA)

Risk Message Risk Score Impact Confidence
a process $Image$ loaded $ImageLoaded$ in $dest$ 9 30 30
The Risk Score is calculated by the following formula: Risk Score = (Impact * Confidence/100). Initial Confidence and Impact is set by the analytic author.

References

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: 3