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Implement delay-token style SSL logging.
This commit moves the notary script into the policy directory, along with some architectural changes: the main SSL script now has functionality to add and remove tokens for a given record. When adding a token, the script delays the logging until the token has been removed or until the record exceeds a maximum delay time. As before, the base SSL script stores all records sequentially and buffers even non-delayed records for the sake of having an ordered log file. If this turns out to be not so important, we can easily revert to a simpler logic. (This is still WiP, some debuggin statements still linger.)
This commit is contained in:
Matthias Vallentin
parent
8a569facd6
commit
9e81342c92
4 changed files with 192 additions and 150 deletions
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@ -1,65 +1,3 @@
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@load ./consts
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module SSL;
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export {
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redef enum Log::ID += { LOG };
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type Info: record {
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## Time when the SSL connection was first detected.
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ts: time &log;
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## Unique ID for the connection.
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uid: string &log;
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## The connection's 4-tuple of endpoint addresses/ports.
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id: conn_id &log;
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## SSL/TLS version that the server offered.
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version: string &log &optional;
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## SSL/TLS cipher suite that the server chose.
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cipher: string &log &optional;
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## Value of the Server Name Indicator SSL/TLS extension. It
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## indicates the server name that the client was requesting.
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server_name: string &log &optional;
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## Session ID offered by the client for session resumption.
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session_id: string &log &optional;
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## Subject of the X.509 certificate offered by the server.
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subject: string &log &optional;
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## Subject of the signer of the X.509 certificate offered by the server.
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issuer_subject: string &log &optional;
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## NotValidBefore field value from the server certificate.
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not_valid_before: time &log &optional;
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## NotValidAfter field value from the server certificate.
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not_valid_after: time &log &optional;
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## Last alert that was seen during the connection.
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last_alert: string &log &optional;
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## Subject of the X.509 certificate offered by the client.
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client_subject: string &log &optional;
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## Subject of the signer of the X.509 certificate offered by the client.
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client_issuer_subject: string &log &optional;
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## Full binary server certificate stored in DER format.
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cert: string &optional;
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## Chain of certificates offered by the server to validate its
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## complete signing chain.
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cert_chain: vector of string &optional;
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## Full binary client certificate stored in DER format.
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client_cert: string &optional;
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## Chain of certificates offered by the client to validate its
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## complete signing chain.
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client_cert_chain: vector of string &optional;
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## The analyzer ID used for the analyzer instance attached
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## to each connection. It is not used for logging since it's a
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## meaningless arbitrary number.
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analyzer_id: count &optional;
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};
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}
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redef record connection += {
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ssl: Info &optional;
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};
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@load ./notary
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@load ./main
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@load ./mozilla-ca-list
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@ -6,6 +6,63 @@
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module SSL;
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export {
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redef enum Log::ID += { LOG };
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type Info: record {
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## Time when the SSL connection was first detected.
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ts: time &log;
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## Unique ID for the connection.
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uid: string &log;
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## The connection's 4-tuple of endpoint addresses/ports.
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id: conn_id &log;
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## SSL/TLS version that the server offered.
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version: string &log &optional;
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## SSL/TLS cipher suite that the server chose.
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cipher: string &log &optional;
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## Value of the Server Name Indicator SSL/TLS extension. It
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## indicates the server name that the client was requesting.
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server_name: string &log &optional;
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## Session ID offered by the client for session resumption.
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session_id: string &log &optional;
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## Subject of the X.509 certificate offered by the server.
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subject: string &log &optional;
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## Subject of the signer of the X.509 certificate offered by the server.
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issuer_subject: string &log &optional;
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## NotValidBefore field value from the server certificate.
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not_valid_before: time &log &optional;
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## NotValidAfter field value from the server certificate.
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not_valid_after: time &log &optional;
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## Last alert that was seen during the connection.
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last_alert: string &log &optional;
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## Subject of the X.509 certificate offered by the client.
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client_subject: string &log &optional;
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## Subject of the signer of the X.509 certificate offered by the client.
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client_issuer_subject: string &log &optional;
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## Full binary server certificate stored in DER format.
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cert: string &optional;
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## Chain of certificates offered by the server to validate its
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## complete signing chain.
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cert_chain: vector of string &optional;
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## Full binary client certificate stored in DER format.
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client_cert: string &optional;
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## Chain of certificates offered by the client to validate its
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## complete signing chain.
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client_cert_chain: vector of string &optional;
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## The analyzer ID used for the analyzer instance attached
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## to each connection. It is not used for logging since it's a
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## meaningless arbitrary number.
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analyzer_id: count &optional;
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## Adding a string "token" to this set will cause the SSL script
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## to delay logging the record until either the token has been removed or
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## the record has been delayed for :bro:id:`SSL::max_log_delay`.
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delay_tokens: set[string] &optional;
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};
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## The default root CA bundle. By loading the
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## mozilla-ca-list.bro script it will be set to Mozilla's root CA list.
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const root_certs: table[string] of string = {} &redef;
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@ -20,11 +77,24 @@ export {
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## utility.
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const openssl_util = "openssl" &redef;
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## The maximum amount of time a plugin can delay records from being logged.
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const max_log_delay = 15secs &redef;
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## TODO: document.
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global add_delayed_record: function(info: Info, token: string);
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## TODO: document.
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global clear_delayed_record: function(uid: string, token: string) : Info;
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## Event that can be handled to access the SSL
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## record as it is sent on to the logging framework.
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global log_ssl: event(rec: Info);
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}
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redef record connection += {
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ssl: Info &optional;
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};
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event bro_init() &priority=5
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{
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Log::create_stream(SSL::LOG, [$columns=Info, $ev=log_ssl]);
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@ -59,6 +129,20 @@ redef likely_server_ports += {
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989/tcp, 990/tcp, 992/tcp, 993/tcp, 995/tcp, 5223/tcp
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};
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# The buffered SSL log records.
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global records: table[string] of Info;
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# A double-ended queue that determines the log record order in which logs have
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# to written out to disk.
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global deque: table[count] of string;
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# The top-most deque index.
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global head = 0;
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# The bottom deque index that points to the next record to be flushed as soon
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# as the notary response arrives.
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global tail = 0;
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function set_session(c: connection)
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{
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if ( ! c?$ssl )
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@ -66,16 +150,69 @@ function set_session(c: connection)
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$client_cert_chain=vector()];
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}
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function add_delayed_record(info: Info, token: string)
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{
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if ( info$uid in records )
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{
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print fmt("----- ignoring duplicate %s -----", info$uid);
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return;
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}
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records[info$uid] = info;
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deque[head] = info$uid;
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++head;
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info$delay_tokens = set();
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add info$delay_tokens[token];
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}
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function clear_delayed_record(uid: string, token: string) : Info
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{
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local info = records[uid];
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delete info$delay_tokens[token];
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return info;
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}
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global log_record: function(info: Info);
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event delay_logging(info: Info)
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{
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log_record(info);
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}
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function log_record(info: Info)
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{
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for ( unused_index in records )
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{
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if ( head == tail )
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return;
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local uid = deque[tail];
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if ( |records[uid]$delay_tokens| > 0 )
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{
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if ( info$ts + max_log_delay > network_time() )
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{
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schedule 1sec { delay_logging(info) };
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return;
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}
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else
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{
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event reporter_info(
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network_time(),
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fmt("SSL delay tokens not released in time (%s)",
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info$delay_tokens),
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"");
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}
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}
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Log::write(SSL::LOG, records[uid]);
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delete records[uid];
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delete deque[tail];
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++tail;
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}
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}
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function finish(c: connection)
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{
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# TODO: This dummy flag merely exists to check whether the notary script is
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# loaded. There's probably a better way to incorporate the notary.
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@ifdef( Notary::enabled )
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Notary::push(c$ssl);
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@else
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Log::write(SSL::LOG, c$ssl);
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@endif
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log_record(c$ssl);
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if ( disable_analyzer_after_detection && c?$ssl && c$ssl?$analyzer_id )
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disable_analyzer(c$id, c$ssl$analyzer_id);
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delete c$ssl;
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@ -179,3 +316,17 @@ event protocol_violation(c: connection, atype: count, aid: count,
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if ( c?$ssl )
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finish(c);
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}
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event bro_done()
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{
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if ( |records| == 0 )
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return;
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for ( unused_index in records )
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{
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local uid = deque[tail];
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Log::write(SSL::LOG, records[uid]);
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delete records[uid];
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delete deque[tail];
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++tail;
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}
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}
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@ -1,10 +1,6 @@
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module Notary;
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export {
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# Flag to tell the SSL analysis script that it should buffer logs instead of
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# flushing them directly.
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const enabled = T;
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## A response from the ICSI certificate notary.
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type Response: record {
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first_seen: count &log &optional;
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@ -13,83 +9,66 @@ export {
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valid: bool &log &optional;
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};
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## Hands over an SSL record to the Notary module. This is an ownership
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## transfer, i.e., the caller does not need to call Log::write on this record
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## anymore.
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global push: function(info: SSL::Info);
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## The notary domain to query.
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const domain = "notary.icsi.berkeley.edu" &redef;
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}
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redef record SSL::Info += {
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sha1_digest: string &optional;
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sha1: string &log &optional;
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notary: Response &log &optional;
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};
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# The DNS cache of notary responses.
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global notary_cache: table[string] of Response &create_expire = 1 hr;
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# The buffered SSL log records.
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global records: table[string] of SSL::Info;
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# The records that wait for a notary response identified by the cert digest.
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# Each digest refers to a list of connection UIDs which are updated when a DNS
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# reply arrives asynchronously.
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global waiting: table[string] of vector of string;
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# A double-ended queue that determines the log record order in which logs have
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# to written out to disk.
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global deque: table[count] of string;
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# The top-most deque index.
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global head = 0;
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# The bottom deque index that points to the next record to be flushed as soon
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# as the notary response arrives.
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global tail = 0;
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function clear_waitlist(digest: string)
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{
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print "----- clearing waitlist -----";
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if ( digest in waiting )
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{
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for ( i in waiting[digest] )
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{
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local uid = waiting[digest][i];
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records[uid]$notary = [];
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print fmt("----- retrieving %s -----", waiting[digest][i]);
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local info = SSL::clear_delayed_record(waiting[digest][i], "notary");
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info$notary = [];
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}
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delete waiting[digest];
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}
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}
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function flush(evict_all: bool)
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event x509_certificate(c: connection, is_orig: bool, cert: X509,
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chain_idx: count, chain_len: count, der_cert: string)
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{
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local current: string;
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for ( unused_index in deque )
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{
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current = deque[tail];
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local info = records[current];
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if ( ! evict_all && ! info?$notary )
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break;
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Log::write(SSL::LOG, info);
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delete deque[tail];
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delete records[current];
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++tail;
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}
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}
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if ( is_orig || chain_idx != 0 || ! c?$ssl )
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return;
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function lookup_cert_hash(uid: string, digest: string)
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j{
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j# Add the record ID to the list of waiting IDs for this digest.
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jlocal waits_already = digest in waiting;
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jif ( ! waits_already )
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local digest = sha1_hash(der_cert);
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c$ssl$sha1 = digest;
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if ( digest in notary_cache )
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{
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c$ssl$notary = notary_cache[digest];
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return;
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}
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print fmt("----- adding %s -----", c$ssl$uid);
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SSL::add_delayed_record(c$ssl, "notary");
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local waits_already = digest in waiting;
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if ( ! waits_already )
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waiting[digest] = vector();
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waiting[digest][|waiting[digest]|] = uid;
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waiting[digest][|waiting[digest]|] = c$uid;
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if ( waits_already )
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return;
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when ( local str = lookup_hostname_txt(fmt("%s.%s", digest, domain)) )
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{
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print fmt("----- when for %s: %s -----", digest, str);
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# Cache every response for a digest.
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notary_cache[digest] = [];
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@ -122,41 +101,11 @@ function lookup_cert_hash(uid: string, digest: string)
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if ( digest in waiting )
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{
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for ( i in waiting[digest] )
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records[waiting[digest][i]]$notary = r;
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{
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local info = SSL::clear_delayed_record(waiting[digest][i], "notary");
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info$notary = r;
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}
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delete waiting[digest];
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}
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flush(F);
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}
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}
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function push(info: SSL::Info)
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{
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if ( ! info?$sha1_digest )
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return;
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local digest = info$sha1_digest;
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if ( info$sha1_digest in notary_cache )
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info$notary = notary_cache[digest];
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else
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lookup_cert_hash(info$uid, digest);
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records[info$uid] = info;
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deque[head] = info$uid;
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++head;
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}
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event x509_certificate(c: connection, is_orig: bool, cert: X509,
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chain_idx: count, chain_len: count, der_cert: string)
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{
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if ( is_orig || chain_idx != 0 || ! c?$ssl )
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return;
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c$ssl$sha1_digest = sha1_hash(der_cert);
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}
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event bro_done()
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{
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if ( |deque| == 0 )
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return;
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flush(T);
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}
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@ -56,6 +56,10 @@ redef Software::vulnerable_versions += {
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# This script enables SSL/TLS certificate validation.
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@load protocols/ssl/validate-certs
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# This script checks each SSL certificate hash against the ICSI certificate
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# notary service.
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@load protocols/ssl/notary
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# If you have libGeoIP support built in, do some geographic detections and
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# logging for SSH traffic.
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@load protocols/ssh/geo-data
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