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Description

this search is designed to detect potential malicious wermgr.exe process that drops or create executable file. Since wermgr.exe is an application trigger when error encountered in a process, it is really un ussual to this process to drop executable file. This technique is commonly seen in trickbot malware where it injects it code to this process to execute it malicious behavior like downloading other payload

  • Type: TTP
  • Product: Splunk Enterprise, Splunk Enterprise Security, Splunk Cloud
  • Datamodel: Endpoint
  • Last Updated: 2021-04-19
  • Author: Teoderick Contreras, Splunk
  • ID: ab3bcce0-a105-11eb-973c-acde48001122

Annotations

ATT&CK
ID Technique Tactic
T1027 Obfuscated Files or Information Defense Evasion
Kill Chain Phase
  • Exploitation
NIST
CIS20
CVE
1
2
3
4
5
`sysmon` EventCode=11 process_name = "wermgr.exe" TargetFilename = "*.exe" 
| stats  min(_time) as firstTime max(_time) as lastTime count by  Image TargetFilename process_name dest EventCode ProcessId 
| `security_content_ctime(firstTime)` 
| `security_content_ctime(lastTime)` 
| `wermgr_process_create_executable_file_filter`

Macros

The SPL above uses the following Macros:

Note that wermgr_process_create_executable_file_filter is a empty macro by default. It allows the user to filter out any results (false positives) without editing the SPL.

Required field

  • _time
  • Image
  • TargetFilename
  • process_name
  • dest
  • EventCode
  • ProcessId

How To Implement

To successfully implement this search, you need to be ingesting logs with the process name, parent process, and command-line executions from your endpoints. If you are using Sysmon, you must have at least version 6.0.4 of the Sysmon TA. Tune and filter known instances of wermgr.exe may be used.

Known False Positives

unknown

Associated Analytic story

RBA

Risk Score Impact Confidence Message
56.0 70 80 Wermgr.exe writing executable files on $dest$

Reference

Test Dataset

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

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