Detection: Linux Shell History Access Via Command Line Utility

Description

The following analytic detects attempts to read shell history files (bash, zsh, fish, etc.). A history file is a log file that records all the commands executed in a shell on a Linux or Unix-based operating system. A malicious actor who gains access to a user's shell history file can potentially obtain sensitive information and use it to compromise the user's system and data.

Search

 1
 2| tstats `security_content_summariesonly`
 3  count min(_time) as firstTime
 4        max(_time) as lastTime
 5
 6from datamodel=Endpoint.Processes where
 7
 8Processes.process_name IN (
 9    "cat",
10    "fmt",
11    "head",
12    "less",
13    "more",
14    "nano",
15    "sort",
16    "tail",
17    "uniq",
18    "vi",
19    "vim"
20)
21Processes.process IN (
22    "*.bash_history*",
23    "*.history*",
24    "*.sh_history*",
25    "*.zhistory*",
26    "*.zsh_history*",
27    "*fish_history*"
28)
29
30by Processes.process Processes.vendor_product Processes.user_id Processes.process_hash
31   Processes.parent_process_name Processes.parent_process_exec Processes.action Processes.dest
32   Processes.process_current_directory Processes.process_path Processes.process_integrity_level
33   Processes.original_file_name Processes.parent_process Processes.parent_process_path
34   Processes.parent_process_guid Processes.parent_process_id Processes.process_guid
35   Processes.process_id Processes.user Processes.process_name
36
37
38| `drop_dm_object_name(Processes)`
39
40| `security_content_ctime(firstTime)`
41
42| `security_content_ctime(lastTime)`
43
44| `linux_shell_history_access_via_command_line_utility_filter`

Data Source

Name	Platform	Sourcetype	Source
Sysmon for Linux EventID 1	Linux	'sysmon:linux'	'Syslog:Linux-Sysmon/Operational'

Macros Used

Annotations

Default Configuration

This detection is configured by default in Splunk Enterprise Security to run with the following settings:

Implementation

The detection is based on data that originates from Endpoint Detection and Response (EDR) agents. These agents are designed to provide security-related telemetry from the endpoints where the agent is installed. To implement this search, you must ingest logs that contain the process GUID, process name, and parent process. Additionally, you must ingest complete command-line executions. These logs must be processed using the appropriate Splunk Technology Add-ons that are specific to the EDR product. The logs must also be mapped to the Processes node of the Endpoint data model. Use the Splunk Common Information Model (CIM) to normalize the field names and speed up the data modeling process.

Known False Positives

Legitimate system administrators and automated scripts may access shell history files for auditing or troubleshooting purposes. Filter based on known administrative accounts and approved tooling in your environment.

Associated Analytic Story

• Compromised Linux Host

• Linux Post-Exploitation

• Linux Privilege Escalation

• Credential Dumping

• Linux Persistence Techniques

Intermediate Findings

Threat Objects

Detection Testing

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

Source: GitHub |

Version: 1