Suspicious PHP Webshell File Creation Linked to BeyondTrust Exploitation (via file_event)

ATT&CK techniques

Persistence

Recon
Resource Dev
Initial Access
Execution
Persistence
- T1505.003Web Shell
Priv Esc
Defense Evasion
Cred Access
Discovery
Lateral Movement
Collection
C2
Exfiltration
Impact

What it detects

This rule detects creation of PHP webshell files named aws.php and file_save.php observed after exploitation of BeyondTrust CVE-2026-1731. These webshells provide persistent remote command execution on the compromised host, so their appearance on a web-accessible path indicates an established foothold.

Reporting behind it

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Suspicious PHP Webshell File Creation Linked to BeyondTrust Exploitation (via file_event)

Pivot detection · T1505.003 · 9 related

Detection content is published as a reviewed draft. Tune thresholds and exclusions against your own telemetry before enabling this rule for alerting.

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