Suspicious ASPX File Written to Kentico CMSPages Directory (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 an aspx file being written into the Kentico CMSPages directory which is the webshell drop location used in the Xperience staging sync RCE chain. New aspx files in this path outside of a controlled upgrade are suspicious.

Reporting behind it

Related detections9 linkedT1505.003 — drag to rearrange

Malicious MOVEit Transfer Web Shell X-siLock-Comment Header (via webserver)

Suspicious MOVEit Transfer human2.aspx Web Shell Access (via webserver)

Suspicious IIS Worker Process Spawning Command or Scripting Interpreter via SharePoint ToolShell Exploitation (via process_creation)

Suspicious Weaver Ant In-Memory Web Shell Marker in Web Request (via webserver)

Malicious Web Server Process Spawning Command Interpreter via Web Shell (via process_creation)

Malicious Web Shell Written to SharePoint LAYOUTS Directory by Worker Process (via file_event)

Malicious IIS Worker Process Spawning Command Shell for Webshell Reconnaissance (via process_creation)

Malicious Command Shell Spawned by SQL Server via Process Creation (via process_creation)

Suspicious PHP Webshell Access with Hardcoded Key

Suspicious ASPX File Written to Kentico CMSPages Directory (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.

Full detection rule

Unlock this rule to view and copy it

The detection logic is included with a plan. Everything else — context, mappings and implementation details — stays free on this page.

Sign in for 3 free unlocks

Signing in gives you 3 unlocks to spend on any rule in the library. No card, and they do not expire.

Also included

Unlocked rules convert on this page — to Splunk SPL or Splunk — Raw Index SPL or Microsoft Sentinel KQL or Microsoft Sentinel ASIM ASIM KQL or Microsoft Defender XDR KQL or Elastic Security KQL or Elastic Security Lucene or Elastic Security ES|QL or CrowdStrike Falcon CQL or SentinelOne PowerQuery or Palo Alto Cortex XDR XQL or Carbon Black Cloud Platform Search or Carbon Black EDR Process Search or Google Security Operations UDM Search or IBM QRadar AQL or Sumo Logic Cloud SIEM Rules expression or Rapid7 InsightIDR LEQL or Graylog Search or OpenSearch Lucene or OpenSearch PPL PPL or Grafana Loki LogQL or SQLite SQL or Zircolite SQLite — with the log-source profile the engine picked, the field map it used, and everything it could not express. Converting a rule you have unlocked costs no further credit.

See it run on a free rule →Convert your own rule →