Suspicious Cobalt Strike Malleable Profile Beaconing via Legacy MSIE9 User-Agent and IE Compatibility URIs (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 Cobalt Strike beacon traffic matching the You Dun malleable profile that pairs a legacy MSIE 9 BOIE9 ENUS user-agent with the IE9CompatViewList and submit.php request URIs on port 80. Adversaries craft malleable profiles to imitate outdated browser telemetry, so this specific combination of an obsolete user-agent and these staging URIs points to attacker command-and-control rather than genuine browsing.

Reporting behind it

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Suspicious Cobalt Strike Malleable Profile Beaconing via Legacy MSIE9 User-Agent and IE Compatibility URIs (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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