TAG-144 Payload Staging via MyCustomAgent User-Agent (via proxy)

ATT&CK techniques

C2

Recon
Resource Dev
Initial Access
Execution
Persistence
Priv Esc
Defense Evasion
Cred Access
Discovery
Lateral Movement
Collection
C2
- T1071.001Web Protocols
- T1105Ingress Tool Transfer
Exfiltration
Impact

What it detects

This rule detects HTTP requests using the hardcoded MyCustomAgent/1.0 user-agent that the TAG-144 loader sets when pulling staged payloads from paste services via ServerXMLHTTP. Adversaries leverage a fixed non-browser user-agent to fetch second-stage code, making this distinctive string a reliable delivery-stage indicator.

Reporting behind it

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TAG-144 Payload Staging via MyCustomAgent User-Agent (via proxy)

Pivot detection · T1105 · 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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