alert http $HOME_NET any -> $EXTERNAL_NET any (msg:"ET MALWARE Win32/Ursnif LDR4 Beacon (POST)"; flow:established,to_server; http.method; content:"POST"; http.uri; content:"/index.html"; bsize:11; http.header_names; content:"|0d 0a|Cache-Control|0d 0a|Connection|0d 0a|Pragma|0d 0a|Content-Type|0d 0a|User-Agent|0d 0a|Content-Length|0d 0a|Host|0d 0a 0d 0a|"; bsize:87; fast_pattern; http.user_agent; content:"Mozilla|2f|5|2e|0|20 28|Windows|20|NT"; startswith; content:"|29 20|AppleWebKit|2f|537|2e|36|20 28|KHTML|2c 20|like|20|Gecko|29 20|Chrome|2f|87|2e|0|2e|4280|2e|66|20|Safari|2f|537|2e|36"; endswith; http.request_body; content:"|2d 2d|"; startswith; content:"|0d 0a|Content|2d|Disposition|3a 20|form|2d|data|3b 20|name|3d 22|"; distance:15; within:42; content:"|2d 2d|"; isdataat:!3,relative; pcre:"/\x2d\x2d(?:\x0d\x0a)?$/P"; reference:url,mandiant.com/resources/blog/rm3-ldr4-ursnif-banking-fraud; reference:md5,b4610d340a9bff58616543b10e961cd3; classtype:command-and-control; sid:2039679; rev:2; metadata:affected_product Windows_XP_Vista_7_8_10_Server_32_64_Bit, attack_target Client_Endpoint, created_at 2022_11_03, deployment Perimeter, deployment SSLDecrypt, malware_family ursnif, confidence High, signature_severity Major, tag Description_Generated_By_Proofpoint_Nexus, updated_at 2023_05_30, reviewed_at 2025_10_24;)