Malicious Cobalt Strike C2 Beaconing via REST URI Paths and Legacy MSIE 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
Exfiltration
Impact

What it detects

This rule detects HTTP command-and-control beaconing that combines the /rest/funcStatus and /rest/policy/3/ URI paths with a legacy MSIE 7.0 .NET CLR User-Agent, a Malleable C2 profile used by a multi-stage Cobalt Strike loader analyzed by Joe Sandbox. Adversaries craft these profiles to blend beacon traffic into ordinary web requests, making the combined URI and User-Agent pattern a reliable signal of an active beacon before hands-on-keyboard activity.

Reporting behind it

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Malicious Cobalt Strike C2 Beaconing via REST URI Paths and Legacy MSIE User-Agent (via proxy)

Pivot detection · T1071.001 · 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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