alert http $HOME_NET any -> $EXTERNAL_NET any (msg:"ET MALWARE Likely APT29 Retrieving Payload Embedded In PNG 3"; flow:established,to_server; http.method; content:"GET"; http.uri; content:".png"; endswith; http.user_agent; content:"?"; startswith; fast_pattern; http.header_names; content:!"|0d 0a|Accept"; content:!"|0d 0a|Referer|0d 0a|"; content:!"|0d 0a|Pragma|0d 0a|"; content:!"|0d 0a|Cache-Control|0d 0a|"; reference:url,researchcenter.paloaltonetworks.com/2016/09/unit42-the-dukes-rd-finds-a-new-anti-analysis-technique/; classtype:targeted-activity; sid:2044214; rev:3; metadata:affected_product Windows_XP_Vista_7_8_10_Server_32_64_Bit, attack_target Client_Endpoint, created_at 2016_10_13, deployment Perimeter, performance_impact Low, confidence Medium, signature_severity Major, updated_at 2024_02_28, former_sid 2822622;)