fix(security): fixing double URL decode of REQUEST_URI #4047
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theseion
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Mar 23, 2025
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You probably need to update test 930110-7? |
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Ready for review. |
theseion
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Mar 25, 2025
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Variable
REQUEST_URIis URL decoded by the engine so we should NOT uset:urlDecodeUni/t:urlDecodeactions with it, otherwise, the value gets URL decoded twice.It looks as better fix for rule
921240to remove actiont:urlDecodeUniand keep usingREQUEST_URIbut it is not as rule runs in phase 1 and, thanks to a bug in modsec2,REQUEST_URIis URL decoded at the start of phase 2. This does not apply for modsec3, where it is URL decoded at the start of phase1, so we need to useREQUEST_URI_RAW+t:urlDecodeUnito keep consistent bahavior accross the engines (by the way, current behavior of this rule differs between modsec2 and 3 as it gets double URL decoded in modsec3 but not in modsec2).Note: Variable
REQUEST_URI_RAWmay contain also domain name (if it was send by client) which is a different behavior fromREQUEST_URIbut it shoud not interfere with affected rules.