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|
SSL/TLS Keywords
================
Suricata comes with several rule keywords to match on various properties of TLS/SSL handshake. Matches are string inclusion matches.
tls.cert_subject
----------------
Match TLS/SSL certificate Subject field.
Examples::
tls.cert_subject; content:"CN=*.googleusercontent.com"; isdataat:!1,relative;
tls.cert_subject; content:"google.com"; nocase; pcre:"/google\.com$/";
``tls.cert_subject`` is a 'sticky buffer'.
``tls.cert_subject`` can be used as ``fast_pattern``.
``tls.cert_subject`` supports multiple buffer matching, see :doc:`multi-buffer-matching`.
tls.subject
~~~~~~~~~~~
Legacy keyword to match TLS/SSL certificate Subject field.
example:
::
tls.subject:"CN=*.googleusercontent.com"
Case sensitive, can't use 'nocase', or other modifiers.
**Note:** ``tls.cert_subject`` replaces the following legacy keywords: ``tls_cert_subject`` and ``tls.subject``.
It's recommended that rules be converted to use the new one.
tls.cert_issuer
---------------
Match TLS/SSL certificate Issuer field.
Examples::
tls.cert_issuer; content:"WoSign"; nocase; isdataat:!1,relative;
tls.cert_issuer; content:"StartCom"; nocase; pcre:"/StartCom$/";
``tls.cert_issuer`` is a 'sticky buffer'.
``tls.cert_issuer`` can be used as ``fast_pattern``.
tls.issuerdn
~~~~~~~~~~~~
Legacy keyword to match TLS/SSL certificate IssuerDN field
example:
::
tls.issuerdn:!"CN=Google-Internet-Authority"
Case sensitive, can't use 'nocase', or other modifiers.
**Note:** ``tls.cert_issuer`` replaces the following legacy keywords: ``tls_cert_issuer`` and ``tls.issuerdn``.
It's recommended that rules be converted to use the new one.
tls.cert_serial
---------------
Match on the serial number in a certificate.
Example::
alert tls any any -> any any (msg:"match cert serial"; \
tls.cert_serial; content:"5C:19:B7:B1:32:3B:1C:A1"; sid:200012;)
``tls.cert_serial`` is a 'sticky buffer'.
``tls.cert_serial`` can be used as ``fast_pattern``.
``tls.cert_serial`` replaces the previous keyword name: ``tls_cert_serial``. You may continue
to use the previous name, but it's recommended that rules be converted to use
the new name.
tls.cert_fingerprint
--------------------
Match on the SHA-1 fingerprint of the certificate.
Example::
alert tls any any -> any any (msg:"match cert fingerprint"; \
tls.cert_fingerprint; \
content:"4a:a3:66:76:82:cb:6b:23:bb:c3:58:47:23:a4:63:a7:78:a4:a1:18"; \
sid:200023;)
``tls.cert_fingerprint`` is a 'sticky buffer'.
``tls.cert_fingerprint`` can be used as ``fast_pattern``.
``tls.cert_fingerprint`` replaces the previous keyword name: ``tls_cert_fingerprint`` may continue
to use the previous name, but it's recommended that rules be converted to use
the new name.
tls.sni
-------
Match TLS/SSL Server Name Indication field.
Examples::
tls.sni; content:"oisf.net"; nocase; isdataat:!1,relative;
tls.sni; content:"oisf.net"; nocase; pcre:"/oisf.net$/";
``tls.sni`` is a 'sticky buffer'.
``tls.sni`` can be used as ``fast_pattern``.
``tls.sni`` replaces the previous keyword name: ``tls_sni``. You may continue
to use the previous name, but it's recommended that rules be converted to use
the new name.
tls_cert_notbefore
------------------
Match on the NotBefore field in a certificate.
Example::
alert tls any any -> any any (msg:"match cert NotBefore"; \
tls_cert_notbefore:1998-05-01<>2008-05-01; sid:200005;)
tls_cert_notafter
-----------------
Match on the NotAfter field in a certificate.
Example::
alert tls any any -> any any (msg:"match cert NotAfter"; \
tls_cert_notafter:>2015; sid:200006;)
tls_cert_expired
----------------
Match returns true if certificate is expired. It evaluates the validity date
from the certificate.
Usage::
tls_cert_expired;
tls_cert_valid
--------------
Match returns true if certificate is not expired. It only evaluates the
validity date. It does *not* do cert chain validation. It is the opposite
of ``tls_cert_expired``.
Usage::
tls_cert_valid;
tls.certs
---------
Do a "raw" match on each of the certificates in the TLS certificate chain.
Example::
alert tls any any -> any any (msg:"match bytes in TLS cert"; tls.certs; \
content:"|06 09 2a 86|"; sid:200070;)
``tls.certs`` is a 'sticky buffer'.
``tls.certs`` can be used as ``fast_pattern``.
``tls.certs`` supports multiple buffer matching, see :doc:`multi-buffer-matching`.
tls.version
-----------
Match on negotiated TLS/SSL version.
Supported values: "1.0", "1.1", "1.2", "1.3"
It is also possible to match versions using a hex string.
Examples::
tls.version:1.2;
tls.version:0x7f12;
The first example matches TLSv1.2, whilst the last example matches TLSv1.3
draft 16.
ssl_version
-----------
Match version of SSL/TLS record.
Supported values "sslv2", "sslv3", "tls1.0", "tls1.1", "tls1.2", "tls1.3"
Example::
alert tls any any -> any any (msg:"match TLSv1.2"; \
ssl_version:tls1.2; sid:200030;)
It is also possible to match on several versions at the same time.
Example::
alert tls any any -> any any (msg:"match SSLv2 and SSLv3"; \
ssl_version:sslv2,sslv3; sid:200031;)
tls.fingerprint
---------------
match TLS/SSL certificate SHA1 fingerprint
example:
::
tls.fingerprint:!"f3:40:21:48:70:2c:31:bc:b5:aa:22:ad:63:d6:bc:2e:b3:46:e2:5a"
Case sensitive, can't use 'nocase'.
The tls.fingerprint buffer is lower case so you must use lower case letters for this to match.
tls.store
---------
store TLS/SSL certificate on disk.
The location can be specified in the `output.tls-store.certs-log-dir` parameter of the yaml configuration file, cf :ref:`suricata-yaml-outputs-tls`..
ssl_state
---------
The ``ssl_state`` keyword matches the state of the SSL connection. The possible states
are ``client_hello``, ``server_hello``, ``client_keyx``, ``server_keyx`` and ``unknown``.
You can specify several states with ``|`` (OR) to check for any of the specified states.
tls.random
----------
Matches on the 32 bytes of the TLS random field.
Example::
alert tls any any -> any any (msg:"TLS random test"; \
tls.random; content:"|9b ce 7a 5e 57 5d 77 02 07 c2 9d be 24 01 cc f0 5d cd e1 d2 a5 86 9c 4a 3e ee 38 db 55 1a d9 bc|"; sid: 200074;)
``tls.random`` is a sticky buffer.
tls.random_time
---------------
Matches on the first 4 bytes of the TLS random field.
Example::
alert tls any any -> any any (msg:"TLS random_time test"; \
tls.random_time; content:"|9b ce 7a 5e|"; sid: 200075;)
``tls.random_time`` is a sticky buffer.
tls.random_bytes
----------------
Matches on the last 28 bytes of the TLS random field.
Example::
alert tls any any -> any any (msg:"TLS random_bytes test"; \
tls.random_bytes; content:"|57 5d 77 02 07 c2 9d be 24 01 cc f0 5d cd e1 d2 a5 86 9c 4a 3e ee 38 db 55 1a d9 bc|"; sid: 200076;)
``tls.random_bytes`` is a sticky buffer.
tls.cert_chain_len
------------------
Matches on the TLS certificate chain length.
tls.cert_chain_len supports `<, >, <>, !` and using an exact value.
Example::
alert tls any any -> any any (msg:"cert chain exact value"; \
tls.cert_chain_len:1; classtype:misc-activity; sid:1; rev:1;)
alert tls any any -> any any (msg:"cert chain less than value"; \
tls.cert_chain_len:<2; classtype:misc-activity; sid:2; rev:1;)
alert tls any any -> any any (msg:"cert chain greater than value"; \
tls.cert_chain_len:>0; classtype:misc-activity; sid:2; rev:1;)
alert tls any any -> any any (msg:"cert chain greater than less than value";\
tls.cert_chain_len:0<>2; classtype:misc-activity; sid:3; rev:1;)
alert tls any any -> any any (msg:"cert chain not value"; \
tls.cert_chain_len:!2; classtype:misc-activity; sid:4; rev:1;)
|
