zeek/scripts/base/protocols/smb/files.zeek
2021-10-20 09:57:09 -07:00

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@load base/frameworks/files
@load ./main
module SMB;
export {
## Default file handle provider for SMB.
global get_file_handle: function(c: connection, is_orig: bool): string;
## Default file describer for SMB.
global describe_file: function(f: fa_file): string;
}
function get_file_handle(c: connection, is_orig: bool): string
{
if ( ! (c$smb_state?$current_file &&
(c$smb_state$current_file?$name ||
c$smb_state$current_file?$path)) )
{
# TODO - figure out what are the cases where this happens.
return "";
}
local current_file = c$smb_state$current_file;
local path_name = current_file?$path ? current_file$path : "";
local file_name = current_file?$name ? current_file$name : "";
# Include last_mod time if available because if a file has been modified it
# should be considered a new file. We use the raw version here to avoid
# getting differences when double precision varies by architecture.
local last_mod = cat(current_file?$times ? current_file$times$modified_raw : 0);
# TODO: This is doing hexdump to avoid problems due to file analysis handling
# using CheckString which is not immune to encapsulated null bytes.
# This needs to be fixed lower in the file analysis code later.
return hexdump(cat(Analyzer::ANALYZER_SMB, c$id$orig_h, c$id$resp_h, path_name, file_name, last_mod));
}
function describe_file(f: fa_file): string
{
# This shouldn't be needed, but just in case...
if ( f$source != "SMB" )
return "";
for ( cid, c in f$conns )
{
if ( c?$smb_state && c$smb_state?$current_file && c$smb_state$current_file?$name )
return c$smb_state$current_file$name;
}
return "";
}
event zeek_init() &priority=5
{
Files::register_protocol(Analyzer::ANALYZER_SMB,
[$get_file_handle = SMB::get_file_handle,
$describe = SMB::describe_file]);
}
event file_over_new_connection(f: fa_file, c: connection, is_orig: bool) &priority=5
{
if ( c?$smb_state && c$smb_state?$current_file )
{
c$smb_state$current_file$fuid = f$id;
if ( c$smb_state$current_file$size > 0 )
f$total_bytes = c$smb_state$current_file$size;
if ( c$smb_state$current_file?$name )
f$info$filename = c$smb_state$current_file$name;
write_file_log(c$smb_state);
}
}