alert tcp $EXTERNAL_NET any -> $HOME_NET [25,587] (msg:"ET EXPLOIT Possible CVE-2014-1761 Inbound SMTP 4"; flow:from_client,established; content:"x1LTU1N"; fast_pattern; pcre:"/^(?:.*?(?:XHUtNTU0|cdS01NT|x1LTU1N)){5}/Rs"; reference:cve,2014-1761; reference:url,blogs.technet.com/b/srd/archive/2014/03/24/security-advisory-2953095-recommendation-to-stay-protected-and-for-detections.aspx; classtype:attempted-user; sid:2018310; rev:7; metadata:created_at 2014_03_25, deprecation_reason Age, confidence Low, signature_severity Major, tag CISA_KEV, updated_at 2023_01_19;)