Possible Aspera Faspex Pre-Auth RCE via YAML Deserialization in package_relay (via webserver)
- Category
- webserver
- Author
- HuntRule
- Published
- 2026-09-07
- Updated
- 2026-09-07
ATT&CK techniques
Initial Access → ExecutionRecon
Resource Dev
Initial Access
Persistence
Priv Esc
Defense Evasion
Cred Access
Discovery
Lateral Movement
Collection
C2
Exfiltration
Impact
What it detects
This rule detects POST requests to the Aspera Faspex package_relay relay_package endpoint, the injection point for a pre-auth RCE where the external_emails field carries a serialized YAML payload deserialized by YAML.load. Attackers abuse this Ruby on Rails unsafe deserialization to execute arbitrary commands. Detecting it surfaces exploitation attempts against internet-facing Faspex servers.
Reporting behind it
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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