zeek/scripts/policy/protocols/ssl/expiring-certs.zeek
2021-10-20 09:57:09 -07:00

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##! Generate notices when X.509 certificates over SSL/TLS are expired or
##! going to expire soon based on the date and time values stored within the
##! certificate.
@load base/protocols/ssl
@load base/files/x509
@load base/frameworks/notice
@load base/utils/directions-and-hosts
module SSL;
export {
redef enum Notice::Type += {
## Indicates that a certificate's NotValidAfter date has lapsed
## and the certificate is now invalid.
Certificate_Expired,
## Indicates that a certificate is going to expire within
## :zeek:id:`SSL::notify_when_cert_expiring_in`.
Certificate_Expires_Soon,
## Indicates that a certificate's NotValidBefore date is future
## dated.
Certificate_Not_Valid_Yet,
};
## The category of hosts you would like to be notified about which have
## certificates that are going to be expiring soon. By default, these
## notices will be suppressed by the notice framework for 1 day after
## a particular certificate has had a notice generated.
## Choices are: LOCAL_HOSTS, REMOTE_HOSTS, ALL_HOSTS, NO_HOSTS
option notify_certs_expiration = LOCAL_HOSTS;
## The time before a certificate is going to expire that you would like
## to start receiving :zeek:enum:`SSL::Certificate_Expires_Soon` notices.
option notify_when_cert_expiring_in = 30days;
}
event ssl_established(c: connection) &priority=3
{
# If there are no certificates or we are not interested in the server, just return.
if ( ! c$ssl?$cert_chain || |c$ssl$cert_chain| == 0 ||
! addr_matches_host(c$id$resp_h, notify_certs_expiration) ||
! c$ssl$cert_chain[0]?$x509 || ! c$ssl$cert_chain[0]?$sha1 )
return;
local fuid = c$ssl$cert_chain[0]$fuid;
local cert = c$ssl$cert_chain[0]$x509$certificate;
local hash = c$ssl$cert_chain[0]$sha1;
if ( cert$not_valid_before > network_time() )
NOTICE([$note=Certificate_Not_Valid_Yet,
$conn=c, $suppress_for=1day,
$msg=fmt("Certificate %s isn't valid until %T", cert$subject, cert$not_valid_before),
$identifier=cat(c$id$resp_h, c$id$resp_p, hash),
$fuid=fuid]);
else if ( cert$not_valid_after < network_time() )
NOTICE([$note=Certificate_Expired,
$conn=c, $suppress_for=1day,
$msg=fmt("Certificate %s expired at %T", cert$subject, cert$not_valid_after),
$identifier=cat(c$id$resp_h, c$id$resp_p, hash),
$fuid=fuid]);
else if ( cert$not_valid_after - notify_when_cert_expiring_in < network_time() )
NOTICE([$note=Certificate_Expires_Soon,
$msg=fmt("Certificate %s is going to expire at %T", cert$subject, cert$not_valid_after),
$conn=c, $suppress_for=1day,
$identifier=cat(c$id$resp_h, c$id$resp_p, hash),
$fuid=fuid]);
}