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4c60dfd6c5
Specifically, set a MIME part's parent_id to the rfc822_msg_fuid if it is set and take into account the current rfc822_msg_fuid for describe_file() to avoid fuid collisions of the top-level RFC822 message and the first MIME part.
84 lines
2.5 KiB
Text
84 lines
2.5 KiB
Text
@load ./main
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@load ./entities
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@load base/utils/conn-ids
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@load base/frameworks/files
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module SMTP;
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export {
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redef record Info += {
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## An ordered vector of file unique IDs seen attached to
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## the message.
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fuids: vector of string &log &default=string_vec();
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## Tracks the fuid of the top-level RFC822 mail message if
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## :zeek:see:`SMTP::enable_rfc822_msg_file_analysis` is set.
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rfc822_msg_fuid: string &optional;
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};
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## Default file handle provider for SMTP.
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global get_file_handle: function(c: connection, is_orig: bool): string;
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## Default file describer for SMTP.
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global describe_file: function(f: fa_file): string;
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}
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function get_file_handle(c: connection, is_orig: bool): string
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{
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# Adding rfc822_msg_fuid here if set to ensure the top-level mail
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# message and the first MIME attachment do not get the same fuid allocated
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# when :zeek:see:`SMTP::enable_rfc822_msg_file_analysis` is set.
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return cat(Analyzer::ANALYZER_SMTP, c$start_time, c$smtp$trans_depth,
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c$smtp?$rfc822_msg_fuid ? c$smtp$rfc822_msg_fuid : "",
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c$smtp_state$mime_depth);
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}
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function describe_file(f: fa_file): string
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{
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# This shouldn't be needed, but just in case...
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if ( f$source != "SMTP" )
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return "";
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for ( _, c in f$conns )
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{
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return SMTP::describe(c$smtp);
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}
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return "";
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}
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event zeek_init() &priority=5
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{
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Files::register_protocol(Analyzer::ANALYZER_SMTP,
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Files::ProtoRegistration($get_file_handle = SMTP::get_file_handle,
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$describe = SMTP::describe_file));
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}
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event file_over_new_connection(f: fa_file, c: connection, is_orig: bool) &priority=5
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{
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if ( c?$smtp && !c$smtp$tls )
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{
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c$smtp$fuids += f$id;
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# If top-level messages are passed to the file analysis
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# framework, the first file within a SMTP transaction is
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# always the top-level RFC822 message. Keep track of it.
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#
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# This allows users to implement a low priority file_over_new_connection()
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# event and check for f$id == c$smtp$rfc822_msg_fuid to attach analyzers
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# to the RFC822 message specifically.
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if ( SMTP::enable_rfc822_msg_file_analysis )
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{
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if ( ! c$smtp?$rfc822_msg_fuid )
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c$smtp$rfc822_msg_fuid = f$id;
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else
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{
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# This is a file representing part of the RFC822
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# message (e.g. the body or a MIME part). If it
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# does not yet have a parent, attach the RFC822
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# fuid as the parent.
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if ( ! f?$parent_id )
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f$parent_id = c$smtp$rfc822_msg_fuid;
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}
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}
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}
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}
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