Suspicious Double-Extension Web Shell Upload via Nagios XI Custom Includes

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 requests to a double-extension .jpg.php file, the upload-filter bypass used against Nagios XI to plant a PHP web shell in the custom-includes directory while posing as an image. Access to such a masqueraded script is a strong indicator of web shell deployment and interaction.

Reporting behind it

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Suspicious Double-Extension Web Shell Upload via Nagios XI Custom Includes

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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