Possible Access-Code Validation Beacon to Malware Delivery C2 (via proxy)

ATT&CK techniques

C2

Recon
Resource Dev
Initial Access
Execution
Persistence
Priv Esc
Defense Evasion
Cred Access
Discovery
Lateral Movement
Collection
C2
- T1102Web Service
Exfiltration
Impact

What it detects

This rule detects HTTP requests to an /api/submit endpoint carrying a code parameter, the access-code validation call made by a DocuSign-themed loader before it retrieves its second stage in a Vidar delivery chain analyzed by Joe Sandbox. Adversaries gate payload delivery behind server-side code validation to evade sandboxes and analysts, so this submit-with-code request pattern surfaces the loader contacting its delivery infrastructure.

Reporting behind it

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Possible Access-Code Validation Beacon to Malware Delivery C2 (via proxy)

Pivot detection · T1102 · 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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