Inline PHP Code Execution
Description
The following analytic detects PHP command-line interpreters executing code supplied directly on the command line with the CLI -r / --run options, or code supplied to PHPDBG through standard input. It covers common CLI executable names on Linux and Windows, including php.exe, php-win.exe, the legacy php-cli.exe name, versioned Linux php binaries, phpdbg, and FrankenPHP's php-cli subcommand. PHP-CGI and PHP-FPM are excluded because they do not support the PHP CLI inline -r option. This behavior can be used legitimately for administration and automation, but unexpected or obfuscated inline PHP execution may indicate an attacker using an installed interpreter to run commands without dropping a script file.
Query · spl
| tstats `security_content_summariesonly`
count min(_time) as firstTime
max(_time) as lastTime
FROM datamodel=Endpoint.Processes WHERE
(
(
Processes.process_name IN (
"php-cli.exe",
"php-win.exe",
"php.exe",
"php",
"php5*",
"php7*",
"php8*",
"php9*",
)
Processes.process IN ("* -r *", "* --run *", "* --run=*")
NOT Processes.process_name IN ("*cgi*", "*fpm*")
)
OR
(
Processes.process_name IN ("phpdbg", "phpdbg.exe")
Processes.process IN ("* -s", "* -s ", "* -s=*")
)
OR
(
Processes.process_name IN ("frankenphp", "frankenphp.exe")
Processes.process= "*php-cli*"
Processes.process= "* -r *"
)
)
by Processes.action Processes.dest Processes.original_file_name
Processes.parent_process Processes.parent_process_exec Processes.parent_process_guid
Processes.parent_process_id Processes.parent_process_name Processes.parent_process_path
Processes.process Processes.process_exec Processes.process_guid
Processes.process_hash Processes.process_id Processes.process_integrity_level
Processes.process_name Processes.process_path Processes.user
Processes.user_id Processes.vendor_product
| `drop_dm_object_name(Processes)`
| `security_content_ctime(firstTime)`
| `security_content_ctime(lastTime)`
| `inline_php_code_execution_filter`
Implementation guide
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
- Developers and administrators may use PHP CLI or PHPDBG for legitimate automation and troubleshooting. Review the command line, parent process, user, host, and execution context. Tune approved automation by host or parent process as needed.
Analyst notes
Known false positives: Developers and administrators may use PHP CLI or PHPDBG for legitimate automation and troubleshooting. Review the command line, parent process, user, host, and execution context. Tune approved automation by host or parent process as needed.