alert tls $EXTERNAL_NET any -> $HOME_NET any (msg:"ET INFO Default PolarSSL/mbedTLS Certificate Issuer Observed in Certificate M1"; flow:established,to_client; tls.cert_issuer; bsize:40; content:"C=NL, O=PolarSSL, CN=Polarssl Test EC CA"; fast_pattern; reference:url,blog.sekoia.io/polaredge-unveiling-an-uncovered-iot-botnet/; reference:url,os.mbed.com/teams/Arcola/code/mbedtls//file/bbdeda018a3c/tests/data_files/Readme-x509.txt/; classtype:misc-activity; sid:2060435; rev:1; metadata:affected_product Any, attack_target IoT, created_at 2025_02_28, deployment Perimeter, performance_impact Low, confidence High, signature_severity Informational, tag mbedTLS, tag PolarEdge, updated_at 2025_02_28, mitre_tactic_id TA0011, mitre_tactic_name Command_And_Control, mitre_technique_id T1573, mitre_technique_name Encrypted_Channel;)