I made a GET request to the URL, http://domain.tld/test/docs/index.php?create_table=1&step=2 and got a 403 response code. It turns out this modsec rule is getting triggered: Access denied with code 403 (phase 2). Pattern match "(?:ogg|gopher|zlib|(?:ht|f)tps?)\:/" at ARGS:gltr_redir. [file "/opt/mod_security/10_asl_rules.conf"] [line "827"] [id "340153"] [rev "22"] [msg "Generic PHP code injection protection via ARGS 3"] [severity "CRITICAL"] I would assume ARGS refers to GET/POST data, but there's no gltr_redir in the query string. And, being a GET request, there's obviously no POST data. So how is this rule being triggered?