6.15. SSL/TLS Keywords¶
Suricata comes with several rule keywords to match on various properties of TLS/SSL handshake. Matches are string inclusion matches.
6.15.1. 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$/";
tls.cert_subject is a ‘sticky buffer’.
tls.cert_subject can be used as fast_pattern.
tls.cert_subject replaces the previous keyword name: tls_cert_subject. You may continue
to use the previous name, but it’s recommended that rules be converted to use
the new name.
6.15.2. tls.cert_issuer¶
Match TLS/SSL certificate Issuer field.
Examples:
tls.cert_issuer; content:"WoSign"; nocase; isdataat:!1,relative;
tls.cert_issuer; content:"StartCom"; nocase; pcre:"/StartCom$/";
tls.cert_issuer is a ‘sticky buffer’.
tls.cert_issuer can be used as fast_pattern.
tls.cert_issuer replaces the previous keyword name: tls_cert_issuer. You may continue
to use the previous name, but it’s recommended that rules be converted to use
the new name.
6.15.3. 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.
6.15.4. 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.
6.15.5. 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.
6.15.6. 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;)
6.15.7. 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;)
6.15.8. tls_cert_expired¶
Match returns true if certificate is expired. It evaluates the validity date from the certificate.
Usage:
tls_cert_expired;
6.15.9. 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;
6.15.10. 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.
6.15.11. 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.
6.15.12. 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;)
6.15.13. tls.subject¶
Match TLS/SSL certificate Subject field.
example:
tls.subject:"CN=*.googleusercontent.com"
Case sensitive, can’t use ‘nocase’.
Legacy keyword. tls.cert_subject is the replacement.
6.15.14. tls.issuerdn¶
match TLS/SSL certificate IssuerDN field
example:
tls.issuerdn:!"CN=Google-Internet-Authority"
Case sensitive, can’t use ‘nocase’.
Legacy keyword. tls.cert_issuer is the replacement.
6.15.15. 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.
6.15.16. tls.store¶
store TLS/SSL certificate on disk
6.15.17. 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.
Negation support is not available yet, see https://redmine.openinfosecfoundation.org/issues/1231