Suspicious ASPX Web Shell Drop on IIS Server

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 web shell files named Errors.aspx, Signoff.aspx or ghost.inc that were planted on internet-facing servers during a stealthy third-party compromise. Web shells give the attacker persistent remote command execution over HTTP which is a common foothold for follow-on lateral movement.

Reporting behind it

Related detections9 linkedT1505.003 — drag to rearrange

Suspicious Web Shell ASPX File Created in Exchange OWA Auth or SharePoint LAYOUTS Path (via file_event)

Suspicious Oracle EBS Web Shell Access via X-ORACLE-DMS-ECID Header

Malicious WIREFIRE Webshell Access on Ivanti Connect Secure API Path (via webserver)

Malicious IIS Worker Process Spawning conn.exe Web Shell Child by APT41 (via process_creation)

Malicious PHASEJAM Web Shell Written Into Ivanti CGI Endpoints (via file_event)

Possible GhostContainer Exchange Backdoor C2 Request via OWA (via webserver)

Suspicious Command Shell Spawned by MSSQL Server Process Indicating Webshell

Suspicious Exchange IIS Worker Loading GhostContainer Module (via image_load)

Malicious MOVEit Transfer Exploitation via X-siLock HTTP Headers (via webserver)

Suspicious ASPX Web Shell Drop on IIS Server

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 →