alert dns $HOME_NET any -> any any (msg:"ET MALWARE OilRig QUADAGENT DNS Tunneling"; dns.query; content:"mail."; nocase; pcre:"/^\d{6}/Ri"; content:".cpuproc.com"; fast_pattern; nocase; endswith; bsize:23; threshold:type limit, count 1, seconds 60, track by_src; reference:md5,d51c2ffce844d42bab2f2c3131e3dbd4; reference:url,researchcenter.paloaltonetworks.com/2018/07/unit42-oilrig-targets-technology-service-provider-government-agency-quadagent/; classtype:trojan-activity; sid:2025894; rev:4; metadata:affected_product Windows_XP_Vista_7_8_10_Server_32_64_Bit, attack_target Client_Endpoint, created_at 2018_07_25, deployment Perimeter, malware_family QuadAgent, performance_impact Low, confidence High, signature_severity Major, tag Description_Generated_By_Proofpoint_Nexus, updated_at 2022_07_21;)