alert smtp $HOME_NET any -> $EXTERNAL_NET any (msg:"ET MALWARE Win32/DarkCloud Variant Exfil over SMTP (FirefoxCookies.json)"; flow:established,to_server; content:"Subject|3a 20|DC-FirefoxCookies.json|3a 3a 3a|"; fast_pattern; content:"Content-Type|3a 20|application/json|3b 0d 0a|"; content:"name|3d 22|FirefoxCookies.json|22 0d 0a|"; distance:0; content:"Content-Transfer-Encoding|3a 20|quoted-printable|0d 0a|"; distance:0; content:"Content-Disposition|3a 20|attachment|3b 0d 0a|"; distance:0; content:"filename|3d 22|FirefoxCookies.json|22 0d 0a 0d 0a|"; distance:0; reference:md5,1d9be2dfd54bf4a986c6cd1b7b630750; classtype:trojan-activity; sid:2044137; rev:1; metadata:affected_product Windows_XP_Vista_7_8_10_Server_32_64_Bit, attack_target Client_Endpoint, created_at 2023_02_06, deployment Perimeter, malware_family Win32_DarkCloud, performance_impact Low, confidence High, signature_severity Major, tag Description_Generated_By_Proofpoint_Nexus, updated_at 2023_02_06;)