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- Since each host in a cluster has it's own view of the metrics the only time the manager would get a chance for a global view is the break_interval. This update improves that time. If a worker crosses 10% of the full threshold, it will send it's value to the manager which can then ask the rest of the cluster for a global view. The manager then adds all of the values for each workers metric indexes together and will do the notice if it crosses the threshold so that it isn't dependent on waiting for the break interval to hit. This functionality works completely independently of the break_interval too. Logging will happen as normal. - Small update for SSH bruteforcer detection to match additions in the metrics framework API. - The hope is that this update is mostly invisible from anyone's perspective. The only affect it should have on users is to better the detection of metric values crossing thresholds on cluster deployments.
71 lines
No EOL
2.3 KiB
Text
71 lines
No EOL
2.3 KiB
Text
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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:`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.
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Login_By_Password_Guesser,
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};
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redef enum Metrics::ID += {
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## This metric is to measure failed logins with the hope of detecting
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## bruteforcing hosts.
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FAILED_LOGIN,
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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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## Keeps track of hosts identified as guessing passwords.
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global password_guessers: set[addr] &read_expire=guessing_timeout+1hr &synchronized;
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}
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event bro_init()
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{
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Metrics::add_filter(FAILED_LOGIN, [$name="detect-bruteforcing", $log=F,
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$note=Password_Guessing,
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$notice_threshold=password_guesses_limit,
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$notice_freq=1hr,
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$break_interval=guessing_timeout]);
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}
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event SSH::heuristic_successful_login(c: connection)
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{
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local id = c$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(FAILED_LOGIN, [$host=id$orig_h], 1);
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} |