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81 lines
2.3 KiB
Text
81 lines
2.3 KiB
Text
##! This script is involved in the identification of file types in HTTP
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##! response bodies.
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@load base/frameworks/signatures
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@load base/frameworks/notice
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@load ./main
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@load ./utils
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# Add the magic number signatures to the core signature set.
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redef signature_files += "base/protocols/http/file-ident.sig";
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# Ignore the signatures used to match files
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redef Signatures::ignored_ids += /^matchfile-/;
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module HTTP;
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export {
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redef enum Notice::Type += {
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# This notice is thrown when the file extension doesn't
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# seem to match the file contents.
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Incorrect_File_Type,
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};
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redef record Info += {
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## This will record the mime_type identified.
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mime_type: string &log &optional;
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## This indicates that no data of the current file transfer has been
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## seen yet. After the first :bro:id:`http_entity_data` event, it
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## will be set to T.
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first_chunk: bool &default=T;
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};
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redef enum Tags += {
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IDENTIFIED_FILE
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};
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# Create regexes that *should* in be in the urls for specifics mime types.
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# Notices are thrown if the pattern doesn't match the url for the file type.
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const mime_types_extensions: table[string] of pattern = {
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["application/x-dosexec"] = /\.([eE][xX][eE]|[dD][lL][lL])/,
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} &redef;
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}
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event signature_match(state: signature_state, msg: string, data: string) &priority=5
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{
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# Only signatures matching file types are dealt with here.
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if ( /^matchfile-/ !in state$sig_id ) return;
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local c = state$conn;
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set_state(c, F, F);
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# Not much point in any of this if we don't know about the HTTP session.
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if ( ! c?$http ) return;
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# Set the mime type that was detected.
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c$http$mime_type = msg;
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if ( msg in mime_types_extensions &&
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c$http?$uri && mime_types_extensions[msg] !in c$http$uri )
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{
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local url = build_url_http(c$http);
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local message = fmt("%s %s %s", msg, c$http$method, url);
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NOTICE([$note=Incorrect_File_Type,
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$msg=message,
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$conn=c,
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$method=c$http$method,
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$URL=url]);
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}
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}
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event http_entity_data(c: connection, is_orig: bool, length: count, data: string) &priority=5
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{
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if ( c$http$first_chunk && ! c$http?$mime_type )
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c$http$mime_type = split1(identify_data(data, T), /;/)[1];
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}
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event http_entity_data(c: connection, is_orig: bool, length: count, data: string) &priority=-10
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{
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if ( c$http$first_chunk )
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c$http$first_chunk=F;
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}
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