The following hunting analytic identifies PowerShell commands utilizing the WindowStyle parameter to hide the window on the compromised endpoint. This combination of command-line options is suspicious because it is overriding the default PowerShell execution policy, attempts to hide its activity from the user, and connects to the Internet. Removed in this version of the query is New-Object. The analytic identifies all variations of WindowStyle, as PowerShell allows the ability to shorten the parameter. For example w, win, windowsty and so forth. In addition, through our research it was identified that PowerShell will interpret different command switch types beyond the hyphen. We have added endash, emdash, horizontal bar, and forward slash.
- Type: Hunting
- Product: Splunk Enterprise, Splunk Enterprise Security, Splunk Cloud
- Datamodel: Endpoint
- Last Updated: 2022-01-12
- Author: David Dorsey, Michael Haag Splunk
- ID: ee18ed37-0802-4268-9435-b3b91aaa18db
|T1059||Command and Scripting Interpreter||Execution|
| tstats `security_content_summariesonly` count min(_time) as firstTime max(_time) as lastTime from datamodel=Endpoint.Processes where `process_powershell` by Processes.user Processes.process_name Processes.process Processes.parent_process_name Processes.original_file_name Processes.dest Processes.process_id | `drop_dm_object_name(Processes)` | `security_content_ctime(firstTime)` | `security_content_ctime(lastTime)` | where match(process,"(?i)[\- |\/ |– |— |―]w(in*d*o*w*s*t*y*l*e*)*\s+[^-]") | `powershell___connect_to_internet_with_hidden_window_filter`
Associated Analytic Story
- Malicious PowerShell
- Possible Backdoor Activity Associated With MUDCARP Espionage Campaigns
- HAFNIUM Group
- Log4Shell CVE-2021-44228
How To Implement
You must be ingesting data that records process activity from your hosts to populate the Endpoint data model in the Processes node. You must also be ingesting logs with both the process name and command line from your endpoints. The command-line arguments are mapped to the "process" field in the Endpoint data model.
Kill Chain Phase
- Command and Control
- Actions on Objectives
Known False Positives
Legitimate process can have this combination of command-line options, but it's not common.
|81.0||90||90||PowerShell processes $process$ started with parameters to modify the execution policy of the run, run in a hidden window, and connect to the Internet on host $dest$ executed by user $user$.|
|CVE-2021-44228||Apache Log4j2 2.0-beta9 through 2.15.0 (excluding security releases 2.12.2, 2.12.3, and 2.3.1) JNDI features used in configuration, log messages, and parameters do not protect against attacker controlled LDAP and other JNDI related endpoints. An attacker who can control log messages or log message parameters can execute arbitrary code loaded from LDAP servers when message lookup substitution is enabled. From log4j 2.15.0, this behavior has been disabled by default. From version 2.16.0 (along with 2.12.2, 2.12.3, and 2.3.1), this functionality has been completely removed. Note that this vulnerability is specific to log4j-core and does not affect log4net, log4cxx, or other Apache Logging Services projects.||9.3|
source | version: 8