php uname

Hunt Hypothesis

The php_uname rule detects potential adversary behavior involving the execution of PHP scripts to gather system information, which may indicate reconnaissance or initial compromise. SOC teams should proactively hunt for this behavior in Azure Sentinel to identify early-stage threats that could lead to deeper system infiltration.

YARA Rule

rule php_uname {
    strings: 
        $ = "php_uname()"
    condition: 
        any of them and filesize < 500KB
}

Deployment Notes

This YARA rule can be deployed in the following contexts:

• Microsoft Defender for Endpoint — Custom indicators / advanced hunting
• Email Gateway — Attachment scanning
• File Share Monitoring — Periodic scanning of shared drives
• YARA CLI — Manual threat hunting on endpoints
• Source Rule

False Positive Guidance

• Scenario: System Information Gathering via php_uname() in Development Environment
  Description: A developer uses php_uname() in a local or staging environment to retrieve system information for debugging or testing.
  Filter/Exclusion: Exclude traffic from known development IP ranges or internal hosts (e.g., src_ip in {10.0.0.0/8, 172.16.0.0/12, 192.168.0.0/16}).

• Scenario: Scheduled Cron Job to Check Server Status
  Description: A scheduled cron job runs a PHP script that uses php_uname() to check server status or log system information for monitoring purposes.
  Filter/Exclusion: Exclude requests with known cron job patterns (e.g., request_uri contains "/cron/check-status" or user_agent contains "cron").

• Scenario: Admin Task to Verify PHP Environment Configuration
  Description: A system administrator runs a PHP script to verify the server’s environment variables or PHP configuration for troubleshooting.
  Filter/Exclusion: Exclude requests originating from admin workstations (e.g., src_ip in {10.10.10.0/24}) or scripts with known admin tool signatures (e.g., request_uri contains "/admin/phpinfo").

• Scenario: Integration with Monitoring Tools (e.g., Nagios, Zabbix)
  Description: A PHP script is used as part of an integration with monitoring tools that require system information for health checks.
  Filter/Exclusion: Exclude traffic from known monitoring tool IPs or user agents (e.g., user_agent contains "Nagios" or "Zabbix").

• Scenario: Legacy Application Using php_uname() for Compatibility
  Description: An older PHP application uses `