alert http any any -> any any (msg:"ET MALWARE [FIREEYE] SLIGHTPULSE Webshell Activity M3"; flow:established,to_client; flowbits:isset,ET.slightpulseM2; http.stat_code; content:"200"; http.header; content:"Cache-Control|3a 20|no-cache|0d 0a|"; http.content_type; content:"image/gif"; bsize:9; fast_pattern; file.data; content:!"<br>"; reference:url,github.com/fireeye/pulsesecure_exploitation_countermeasures; reference:url,www.fireeye.com/blog/threat-research/2021/04/suspected-apt-actors-leverage-bypass-techniques-pulse-secure-zero-day.html; classtype:command-and-control; sid:2032913; rev:2; metadata:attack_target Client_Endpoint, created_at 2021_05_05, deployment Perimeter, deployment SSLDecrypt, performance_impact Significant, confidence High, signature_severity Major, tag Description_Generated_By_Proofpoint_Nexus, updated_at 2021_05_05;)