This analytic is to look for possible ssh key file creation on ~/.ssh/ folder. This technique is commonly abused by threat actors and adversaries to gain persistence and privilege escalation to the targeted host. by creating ssh private and public key and passing the public key to the attacker server. threat actor can access remotely the machine using openssh daemon service.
- Type: Anomaly
- Product: Splunk Enterprise, Splunk Enterprise Security, Splunk Cloud
- Datamodel: Endpoint
- Last Updated: 2022-01-11
- Author: Teoderick Contreras, Splunk
- ID: c04ef40c-72da-11ec-8eac-acde48001122
Kill Chain Phase
- CIS 3
- CIS 5
- CIS 16
1 2 3 4 5 6 | tstats `security_content_summariesonly` count min(_time) as firstTime max(_time) as lastTime FROM datamodel=Endpoint.Filesystem where Filesystem.file_path IN ("*/.ssh*") by Filesystem.dest Filesystem.file_name Filesystem.process_guid Filesystem.file_path | `drop_dm_object_name(Filesystem)` | `security_content_ctime(lastTime)` | `security_content_ctime(firstTime)` | `linux_possible_ssh_key_file_creation_filter`
The SPL above uses the following Macros:
linux_possible_ssh_key_file_creation_filter is a empty macro by default. It allows the user to filter out any results (false positives) without editing the SPL.
How To Implement
To successfully implement this search, you need to be ingesting logs with the file name, file path, and process_guid executions from your endpoints. If you are using Sysmon, you can use the Add-on for Linux Sysmon from Splunkbase.
Known False Positives
Administrator or network operator can create file in ~/.ssh folders for automation purposes. Please update the filter macros to remove false positives.
Associated Analytic story
|36.0||60||60||A file $file_name$ is created in $file_path$ on $dest$|
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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