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Description

This analytic is to look for possible execution of SysReq hack to reboot the Linux system host. This technique was seen in Awfulshred malware wiper to reboot the compromised host by using the linux magic sysreq key. This kernel configuration can trigger reboot by piping out 'b' to /proc/sysrq-trigger after enabling all the functions of sysrq. This TTP detection can be a good indicator of possible suspicious processes running on the Linux host since this command is not a common way to reboot a system.

  • Type: TTP
  • Product: Splunk Enterprise, Splunk Enterprise Security, Splunk Cloud
  • Datamodel: Endpoint
  • Last Updated: 2023-02-08
  • Author: Teoderick Contreras, Splunk
  • ID: e1912b58-ed9c-422c-bbb0-2dbc70398345

Annotations

ATT&CK

ATT&CK

ID Technique Tactic
T1529 System Shutdown/Reboot Impact
Kill Chain Phase
  • Exploitation
NIST
  • DE.CM
CIS20
  • CIS 3
  • CIS 5
  • CIS 16
CVE 


1
2
3
4
5



| tstats `security_content_summariesonly` count min(_time) as firstTime max(_time) as lastTime from datamodel=Endpoint.Processes where Processes.process_name IN ("dash", "sudo", "bash")  Processes.process =  "* echo b > *" Processes.process = "*/proc/sysrq-trigger" by Processes.dest Processes.user Processes.parent_process_name Processes.process_name Processes.process Processes.process_id Processes.parent_process_id Processes.process_guid 
| `drop_dm_object_name(Processes)` 
| `security_content_ctime(firstTime)` 
| `linux_system_reboot_via_system_request_key_filter`

Macros

The SPL above uses the following Macros:

:information_source: linux_system_reboot_via_system_request_key_filter is a empty macro by default. It allows the user to filter out any results (false positives) without editing the SPL.

Required fields

List of fields required to use this analytic.

  • _time
  • Processes.dest
  • Processes.user
  • Processes.parent_process_name
  • Processes.parent_process
  • Processes.process_name
  • Processes.process_path
  • Processes.process
  • Processes.process_id
  • Processes.parent_process_id

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 can use the Add-on for Linux Sysmon from Splunkbase.

Known False Positives

unknown

Associated Analytic Story

RBA

Risk Score Impact Confidence Message
49.0 70 70 a $process_name$ execute sysrq command $process$ to reboot $dest$

:information_source: The Risk Score is calculated by the following formula: Risk Score = (Impact * Confidence/100). Initial Confidence and Impact is set by the analytic author.

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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