alert tcp $HOME_NET any -> $EXTERNAL_NET 80 (
msg:"ET HUNTING SUSPICIOUS Possible automated connectivity check (www.yahoo.com)";
flow:established,to_server;
dsize:39;
content:"GET / HTTP/1.";
content:"|0d 0a|Host|3a 20|www.yahoo.com|0d 0a 0d 0a|"; distance:1; within:25; fast_pattern;
threshold:type limit, count 1, seconds 300, track by_src;
classtype:bad-unknown;
sid:2018433; rev:2;
metadata:affected_product Web_Browsers, affected_product Web_Browser_Plugins, attack_target Client_Endpoint, created_at 2014_04_30, deployment Perimeter, confidence Medium, signature_severity Major, tag Web_Client_Attacks, updated_at 2022_03_17, reviewed_at 2024_03_06;
)