The added disable-certificate-events-known-certs.zeek disables repeated
X509 events in SSL connections, given that the connection terminates at
the same server and used the samt SNI as a previously seen connection
with the same certificate.
For people that see significant amounts of TLS 1.2 traffic, this could
reduce the amount of raised events significantly - especially when a
lot of connections are repeat connections to the same servers.
The practical impact of not raising these events is actually very little
- unless a script directly interacts with the x509 events, everything
works as before - the x509 variables in the connection records are still
being set (from the cache).
In the past I thought that this is not super interesting. However, it
turns out that this can actually contain a slew of interresting
information - like operating systems querying for the revocation of
software signing certificates, e.g.
So - let's just enable this as a default log for the future.
This adds a "policy" hook into the logging framework's streams and
filters to replace the existing log filter predicates. The hook
signature is as follows:
hook(rec: any, id: Log::ID, filter: Log::Filter);
The logging manager invokes hooks on each log record. Hooks can veto
log records via a break, and modify them if necessary. Log filters
inherit the stream-level hook, but can override or remove the hook as
needed.
The distribution's existing log streams now come with pre-defined
hooks that users can add handlers to. Their name is standardized as
"log_policy" by convention, with additional suffixes when a module
provides multiple streams. The following adds a handler to the Conn
module's default log policy hook:
hook Conn::log_policy(rec: Conn::Info, id: Log::ID, filter: Log::Filter)
{
if ( some_veto_reason(rec) )
break;
}
By default, this handler will get invoked for any log filter
associated with the Conn::LOG stream.
The existing predicates are deprecated for removal in 4.1 but continue
to work.
Typically in base scripts, Log::create_stream() is called in zeek_init()
handler with &priority=5 such that it will have already been created
in the default zeek_init() &priority=0.
These are no longer loaded by default due to the performance impact they
cause simply by being loaded (they have event handlers for commonly
generated events) and they aren't generally useful enough to justify it.
Closes#1830.
* origin/topic/johanna/ocsp-sct-validate: (82 commits)
Tiny script changes for SSL.
Update CT Log list
SSL: Update OCSP/SCT scripts and documentation.
Revert "add parameter 'status_type' to event ssl_stapled_ocsp"
Revert "parse multiple OCSP stapling responses"
SCT: Fix script error when mime type of file unknown.
SCT: another memory leak in SCT parsing.
SCT validation: fix small memory leak (public keys were not freed)
Change end-of-connection handling for validation
OCSP/TLS/SCT: Fix a number of test failures.
SCT Validate: make caching a bit less aggressive.
SSL: Fix type of ssl validation result
TLS-SCT: compile on old versions of OpenSSL (1.0.1...)
SCT: Add caching support for validation
SCT: Add signed certificate timestamp validation script.
SCT: Allow verification of SCTs in Certs.
SCT: only compare correct OID/NID for Cert/OCSP.
SCT: add validation of proofs for extensions and OCSP.
SCT: pass timestamp as uint64 instead of time
Add CT log information to Bro
...
Re-enable logging, now in policy because it probably is interesting to
no-one. We also only log ocsp replies.
Fix all tests.
Fix an issue where ocsp replies were added to the x.509 certificate
list.
