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d9195076b1
- New scan.bro merged in and reworked a bit. - Updated metrics API. Now possible to calculate much more.
79 lines
2.9 KiB
Text
79 lines
2.9 KiB
Text
##! Detect hosts which are doing password guessing attacks and/or password
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##! bruteforcing over SSH.
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@load base/protocols/ssh
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@load base/frameworks/metrics
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@load base/frameworks/notice
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@load base/frameworks/intel
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module SSH;
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export {
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redef enum Notice::Type += {
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## Indicates that a host has been identified as crossing the
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## :bro:id:`SSH::password_guesses_limit` threshold with heuristically
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## determined failed logins.
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Password_Guessing,
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## Indicates that a host previously identified as a "password guesser"
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## has now had a heuristically successful login attempt. This is not
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## currently implemented.
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Login_By_Password_Guesser,
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};
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## The number of failed SSH connections before a host is designated as
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## guessing passwords.
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const password_guesses_limit = 30 &redef;
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## The amount of time to remember presumed non-successful logins to build
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## model of a password guesser.
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const guessing_timeout = 30 mins &redef;
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## This value can be used to exclude hosts or entire networks from being
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## tracked as potential "guessers". There are cases where the success
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## heuristic fails and this acts as the whitelist. The index represents
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## client subnets and the yield value represents server subnets.
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const ignore_guessers: table[subnet] of subnet &redef;
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## Tracks hosts identified as guessing passwords.
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global password_guessers: set[addr]
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&read_expire=guessing_timeout+1hr &synchronized &redef;
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}
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event bro_init()
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{
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Metrics::add_filter("ssh.login.failure", [$name="detect-bruteforcing", $log=F,
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$every=guessing_timeout,
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$measure=set(Metrics::SUM),
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$threshold=password_guesses_limit,
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$threshold_crossed(index: Metrics::Index, val: Metrics::ResultVal) = {
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NOTICE([$note=Password_Guessing,
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$msg=fmt("%s appears to be guessing SSH passwords (seen in %.0f connections).", index$host, val$sum),
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$src=index$host,
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$identifier=cat(index$host)]);
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}]);
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}
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event SSH::heuristic_successful_login(c: connection)
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{
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local id = c$id;
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# TODO: This is out for the moment pending some more additions to the
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# metrics framework.
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#if ( id$orig_h in password_guessers )
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# {
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# NOTICE([$note=Login_By_Password_Guesser,
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# $conn=c,
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# $msg=fmt("Successful SSH login by password guesser %s", id$orig_h)]);
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# }
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}
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event SSH::heuristic_failed_login(c: connection)
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{
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local id = c$id;
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# Add data to the FAILED_LOGIN metric unless this connection should
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# be ignored.
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if ( ! (id$orig_h in ignore_guessers &&
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id$resp_h in ignore_guessers[id$orig_h]) )
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Metrics::add_data("ssh.login.failure", [$host=id$orig_h], [$num=1]);
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}
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