Linux System Reboot Via System Request Key
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
Kill Chain Phase
- CIS 3
- CIS 5
- CIS 16
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`
The SPL above uses the following Macros:
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.
List of fields required to use this analytic.
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
Associated Analytic Story
|49.0||70||70||a $process_name$ execute sysrq command $process$ to reboot $dest$|
The Risk Score is calculated by the following formula: Risk Score = (Impact * Confidence/100). Initial Confidence and Impact is set by the analytic author.
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