Zeek_SSL.events.bif.zeek

GLOBAL

Namespace: GLOBAL

Summary

Events

`ssl_alert`: `event`	Generated for SSL/TLS alert records.
`ssl_certificate_request`: `event`	This event is raised, when a Certificate Request handshake message is encountered.
`ssl_change_cipher_spec`: `event`	This event is raised when a SSL/TLS ChangeCipherSpec message is encountered before encryption begins.
`ssl_client_hello`: `event`	Generated for an SSL/TLS client’s initial hello message.
`ssl_connection_flipped`: `event`	Zeek typically assumes that the originator of a connection is the client of the SSL/TLS session.
`ssl_dh_client_params`: `event`	Generated if a client uses a DH-anon or DHE cipher suite.
`ssl_dh_server_params`: `event`	Generated if a server uses a DH-anon or DHE cipher suite.
`ssl_ecdh_client_params`: `event`	Generated if a client uses an ECDH-anon or ECDHE cipher suite.
`ssl_ecdh_server_params`: `event`	Generated if a server uses an ECDH-anon or ECDHE cipher suite using a named curve This event contains the named curve name and the server ECDH parameters contained in the ServerKeyExchange message as defined in RFC 4492.
`ssl_encrypted_data`: `event`	Generated for SSL/TLS messages that are sent after session encryption started.
`ssl_established`: `event`	Generated at the end of an SSL/TLS handshake.
`ssl_extension`: `event`	Generated for SSL/TLS extensions seen in an initial handshake.
`ssl_extension_application_layer_protocol_negotiation`: `event`	Generated for an SSL/TLS Application-Layer Protocol Negotiation extension.
`ssl_extension_connection_id`: `event`	Generated for an DTLS Connection ID extension.
`ssl_extension_ec_point_formats`: `event`	Generated for an SSL/TLS Supported Point Formats extension.
`ssl_extension_elliptic_curves`: `event`	Generated for an SSL/TLS Elliptic Curves extension.
`ssl_extension_key_share`: `event`	Generated for a Key Share extension.
`ssl_extension_pre_shared_key_client_hello`: `event`	Generated for the pre-shared key extension as it is sent in the TLS 1.3 client hello.
`ssl_extension_pre_shared_key_server_hello`: `event`	Generated for the pre-shared key extension as it is sent in the TLS 1.3 server hello.
`ssl_extension_psk_key_exchange_modes`: `event`	Generated for an TLS Pre-Shared Key Exchange Modes extension.
`ssl_extension_server_name`: `event`	Generated for an SSL/TLS Server Name extension.
`ssl_extension_signature_algorithm`: `event`	Generated for an Signature Algorithms extension.
`ssl_extension_signed_certificate_timestamp`: `event`	Generated for the signed_certificate_timestamp TLS extension as defined in RFC 6962.
`ssl_extension_supported_versions`: `event`	Generated for an TLS Supported Versions extension.
`ssl_handshake_message`: `event`	This event is raised for each unencrypted SSL/TLS handshake message.
`ssl_heartbeat`: `event`	Generated for SSL/TLS heartbeat messages that are sent before session encryption starts.
`ssl_plaintext_data`: `event`	Generated for SSL/TLS messages that are sent before full session encryption starts.
`ssl_probable_encrypted_handshake_message`: `event`	This event is generated for application data records of TLS 1.3 connections of which we suspect that they contain handshake messages.
`ssl_rsa_client_pms`: `event`	Generated if a client uses RSA key exchange.
`ssl_server_hello`: `event`	Generated for an SSL/TLS server’s initial hello message.
`ssl_server_signature`: `event`	Generated if a server uses a non-anonymous DHE or ECDHE cipher suite.
`ssl_session_ticket_handshake`: `event`	Generated for SSL/TLS handshake messages that are a part of the stateless-server session resumption mechanism.
`ssl_stapled_ocsp`: `event`	This event contains the OCSP response contained in a Certificate Status Request message, when the client requested OCSP stapling and the server supports it.

Detailed Interface

Events

ssl_alert 

Type: event (c: connection, is_client: bool, level: count, desc: count)

Generated for SSL/TLS alert records. SSL/TLS sessions start with an unencrypted handshake, and Zeek extracts as much information out of that as it can. If during that handshake, an endpoint encounters a fatal error, it sends an alert record, that in turn triggers this event. After an alert, any endpoint may close the connection immediately.

See Wikipedia for more information about the SSL/TLS protocol.

Parameters

c – The connection.
is_client – True if event is raised for the client side of the connection (the side that sends the client hello). This is typically equivalent with the originator, but does not have to be in all circumstances.
level – The severity level, as sent in the alert. The values are defined as part of the SSL/TLS protocol.
desc – A numerical value identifying the cause of the alert. The values are defined as part of the SSL/TLS protocol.

ssl_certificate_request 

Type: event (c: connection, is_client: bool, certificate_types: index_vec, supported_signature_algorithms: signature_and_hashalgorithm_vec, certificate_authorities: string_vec)

This event is raised, when a Certificate Request handshake message is encountered. This Message can be used by a TLS server to request a client certificate.

Parameters

c – The connection.
is_client – True if event is raised for the client side of the connection (the side that sends the client hello). This is typically equivalent with the originator, but does not have to be in all circumstances.
certificate_types – List of the types of certificates that the client may offer.
supported_signature_algorithms – List of hash/sighature algorithm pairs that the server supports, listed in descending order of preferences.
certificate_authorities – List of distinguished names of certificate authorities that are acceptable to the server. The individual entries are DER encoded. parse_distinguished_name can be used to decode the strings.

ssl_change_cipher_spec

Type: event (c: connection, is_client: bool)

This event is raised when a SSL/TLS ChangeCipherSpec message is encountered before encryption begins. Traffic will be encrypted following this message.

Parameters

c – The connection.
is_client – True if event is raised for the client side of the connection (the side that sends the client hello). This is typically equivalent with the originator, but does not have to be in all circumstances.

ssl_client_hello

Type: event (c: connection, version: count, record_version: count, possible_ts: time, client_random: string, session_id: string, ciphers: index_vec, comp_methods: index_vec)

Generated for an SSL/TLS client’s initial hello message. SSL/TLS sessions start with an unencrypted handshake, and Zeek extracts as much information out of that as it can. This event provides access to the initial information sent by the client.

See Wikipedia for more information about the SSL/TLS protocol.

Parameters

c – The connection.
version – The protocol version as extracted from the client’s message. The values are standardized as part of the SSL/TLS protocol. The SSL::version_strings table maps them to descriptive names.
record_version – TLS version given in the record layer of the message. Set to 0 for SSLv2.
possible_ts – The current time as sent by the client. Note that SSL/TLS does not require clocks to be set correctly, so treat with care.
session_id – The session ID sent by the client (if any).
client_random – The random value sent by the client. For version 2 connections, the client challenge is returned.
ciphers – The list of ciphers the client offered to use. The values are standardized as part of the SSL/TLS protocol. The SSL::cipher_desc table maps them to descriptive names.
comp_methods – The list of compression methods that the client offered to use. This value is not sent in TLSv1.3 or SSLv2.

ssl_connection_flipped 

Type: event (c: connection)

Zeek typically assumes that the originator of a connection is the client of the SSL/TLS session. In some scenarios this does not hold, and the responder of a connection is the client, and the initiator is the server.

In these cases, Zeek raises this event. Connection direction is detected by looking at the server hello, client hello, and hello request handshake messages.

Parameters: c – The connection.

ssl_dh_client_params

Type: event (c: connection, Yc: string)

Generated if a client uses a DH-anon or DHE cipher suite. This event contains the client DH parameters contained in the ClientKeyExchange message as defined in RFC 5246.

Parameters

c – The connection.
Yc – The client’s DH public key.

ssl_dh_server_params

Type: event (c: connection, p: string, q: string, Ys: string)

Generated if a server uses a DH-anon or DHE cipher suite. This event contains the server DH parameters, contained in the ServerKeyExchange message as defined in RFC 5246.

Parameters

c – The connection.
p – The DH prime modulus.
q – The DH generator.
Ys – The server’s DH public key.

ssl_ecdh_client_params

Type: event (c: connection, point: string)

Generated if a client uses an ECDH-anon or ECDHE cipher suite. This event contains the client ECDH public value contained in the ClientKeyExchange message as defined in RFC 4492.

Parameters

c – The connection.
point – The client’s ECDH public key.

ssl_ecdh_server_params 

Type: event (c: connection, curve: count, point: string)

Generated if a server uses an ECDH-anon or ECDHE cipher suite using a named curve This event contains the named curve name and the server ECDH parameters contained in the ServerKeyExchange message as defined in RFC 4492.

Parameters

c – The connection.
curve – The curve parameters.
point – The server’s ECDH public key.

ssl_encrypted_data 

Type: event (c: connection, is_client: bool, record_version: count, content_type: count, length: count)

Generated for SSL/TLS messages that are sent after session encryption started.

Note that SSL::disable_analyzer_after_detection has to be changed from its default to false for this event to be generated.

Also note that, for DTLS 1.3, it is not always possible to give an exact length for the payload that is transported in the packet. If connection IDs are used, the length provided is the length of the entire packet, without the first byte (for the unified header). If no connection IDs are used, the length given is the actual payload length. Connection IDs are used with the connection ID extension in the client or server hello.

Parameters

c – The connection.
is_client – True if event is raised for the client side of the connection (the side that sends the client hello). This is typically equivalent with the originator, but does not have to be in all circumstances.
record_version – TLS version given in the record layer of the message. Set to 0 for SSLv2.
content_type – message type as reported by TLS session layer. Not populated for SSLv2.
length – length of the encrypted payload in the record.

ssl_established

Type: event (c: connection)

Generated at the end of an SSL/TLS handshake. SSL/TLS sessions start with an unencrypted handshake, and Zeek extracts as much information out of that as it can. This event signals the time when an SSL/TLS has finished the handshake and its endpoints consider it as fully established. Typically, everything from now on will be encrypted.

See Wikipedia for more information about the SSL/TLS protocol.

Parameters: c – The connection.

ssl_extension

Type: event (c: connection, is_client: bool, code: count, val: string)

Generated for SSL/TLS extensions seen in an initial handshake. SSL/TLS sessions start with an unencrypted handshake, and Zeek extracts as much information out of that as it can. This event provides access to any extensions either side sends as part of an extended hello message.

Note that Zeek offers more specialized events for a few extensions.

Parameters

c – The connection.
is_client – True if event is raised for the client side of the connection (the side that sends the client hello). This is typically equivalent with the originator, but does not have to be in all circumstances.
code – The numerical code of the extension. The values are standardized as part of the SSL/TLS protocol. The SSL::extensions table maps them to descriptive names.
val – The raw extension value that was sent in the message.

ssl_extension_application_layer_protocol_negotiation

Type: event (c: connection, is_client: bool, protocols: string_vec)

Generated for an SSL/TLS Application-Layer Protocol Negotiation extension. This TLS extension is defined in draft-ietf-tls-applayerprotoneg and sent in the initial handshake. It contains the list of client supported application protocols by the client or the server, respectively.

At the moment it is mostly used to negotiate the use of SPDY / HTTP2.

Parameters

c – The connection.
is_client – True if event is raised for the client side of the connection (the side that sends the client hello). This is typically equivalent with the originator, but does not have to be in all circumstances.
protocols – List of supported application layer protocols.

ssl_extension_connection_id

Type: event (c: connection, is_client: bool, cid: string)

Generated for an DTLS Connection ID extension. This TLS extension is defined in the RFC 9146 and sent by the client or the server to signify that Connection IDs should be used for the connection.

Parameters

c – The connection.
is_client – True if event is raised for the client side of the connection (the side that sends the client hello). This is typically equivalent with the originator, but does not have to be in all circumstances.
cid – The connection ID given by the client or the server.

ssl_extension_ec_point_formats 

Type: event (c: connection, is_client: bool, point_formats: index_vec)

Generated for an SSL/TLS Supported Point Formats extension. This TLS extension is defined in RFC 4492 and sent by the client and/or server in the initial handshake. It gives the list of elliptic curve point formats supported by the client.

Parameters

c – The connection.
is_client – True if event is raised for the client side of the connection (the side that sends the client hello). This is typically equivalent with the originator, but does not have to be in all circumstances.
point_formats – List of supported point formats.

ssl_extension_elliptic_curves 

Type: event (c: connection, is_client: bool, curves: index_vec)

Generated for an SSL/TLS Elliptic Curves extension. This TLS extension is defined in RFC 4492 and sent by the client in the initial handshake. It gives the list of elliptic curves supported by the client.

Parameters

c – The connection.
is_client – True if event is raised for the client side of the connection (the side that sends the client hello). This is typically equivalent with the originator, but does not have to be in all circumstances.
curves – List of supported elliptic curves.

ssl_extension_key_share

Type: event (c: connection, is_client: bool, curves: index_vec)

Generated for a Key Share extension. This TLS extension is defined in TLS1.3-draft16 and sent by the client and the server in the initial handshake. It gives the list of named groups supported by the client and chosen by the server.

Parameters

c – The connection.
is_client – True if event is raised for the client side of the connection (the side that sends the client hello). This is typically equivalent with the originator, but does not have to be in all circumstances.
curves – List of supported/chosen named groups.

ssl_extension_pre_shared_key_client_hello

Type: event (c: connection, is_client: bool, identities: psk_identity_vec, binders: string_vec)

Generated for the pre-shared key extension as it is sent in the TLS 1.3 client hello.

The extension lists the identities the client is willing to negotiate with the server; they can either be pre-shared or be based on previous handshakes.

Parameters

c – The connection.
is_client – True if event is raised for the client side of the connection (the side that sends the client hello). This is typically equivalent with the originator, but does not have to be in all circumstances.
identities – A list of the identities the client is willing to negotiate with the server.
binders – A series of HMAC values; for computation, see the TLS 1.3 RFC.

ssl_extension_pre_shared_key_server_hello

Type: event (c: connection, is_client: bool, selected_identity: count)

Generated for the pre-shared key extension as it is sent in the TLS 1.3 server hello.

Parameters

c – The connection.
is_client – True if event is raised for the client side of the connection (the side that sends the client hello). This is typically equivalent with the originator, but does not have to be in all circumstances.
selected_identity – The identity the server chose as a 0-based index into the identities the client sent.

ssl_extension_psk_key_exchange_modes 

Type: event (c: connection, is_client: bool, modes: index_vec)

Generated for an TLS Pre-Shared Key Exchange Modes extension. This TLS extension is defined in the TLS 1.3 rfc and sent by the client in the initial handshake. It contains the list of Pre-Shared Key Exchange Modes that it supports.

Parameters

c – The connection.
is_client – True if event is raised for the client side of the connection (the side that sends the client hello). This is typically equivalent with the originator, but does not have to be in all circumstances.
versions – List of supported Pre-Shared Key Exchange Modes.

ssl_extension_server_name

Type: event (c: connection, is_client: bool, names: string_vec)

Generated for an SSL/TLS Server Name extension. This SSL/TLS extension is defined in RFC 3546 and sent by the client in the initial handshake. It contains the name of the server it is contacting. This information can be used by the server to choose the correct certificate for the host the client wants to contact.

Parameters

c – The connection.
is_client – True if event is raised for the client side of the connection (the side that sends the client hello). This is typically equivalent with the originator, but does not have to be in all circumstances.
names – A list of server names (DNS hostnames).

ssl_extension_signature_algorithm 

Type: event (c: connection, is_client: bool, signature_algorithms: signature_and_hashalgorithm_vec)

Generated for an Signature Algorithms extension. This TLS extension is defined in RFC 5246 and sent by the client in the initial handshake. It gives the list of signature and hash algorithms supported by the client.

Parameters

c – The connection.
is_client – True if event is raised for the client side of the connection (the side that sends the client hello). This is typically equivalent with the originator, but does not have to be in all circumstances.
signature_algorithms – List of supported signature and hash algorithm pairs.

ssl_extension_signed_certificate_timestamp 

Type: event (c: connection, is_client: bool, version: count, logid: string, timestamp: count, signature_and_hashalgorithm: SSL::SignatureAndHashAlgorithm, signature: string)

Generated for the signed_certificate_timestamp TLS extension as defined in RFC 6962. The extension is used to transmit signed proofs that are used for Certificate Transparency.

Parameters

c – The connection.
is_client – True if event is raised for the client side of the connection (the side that sends the client hello). This is typically equivalent with the originator, but does not have to be in all circumstances.
version – the version of the protocol to which the SCT conforms. Always should be 0 (representing version 1)
logid – 32 bit key id
timestamp – the NTP Time when the entry was logged measured since the epoch, ignoring leap seconds, in milliseconds.
signature_and_hashalgorithm – signature and hash algorithm used for the digitally_signed struct
signature – signature part of the digitally_signed struct

ssl_extension_supported_versions

Type: event (c: connection, is_client: bool, versions: index_vec)

Generated for an TLS Supported Versions extension. This TLS extension is defined in the TLS 1.3 rfc and sent by the client in the initial handshake. It contains the TLS versions that it supports. This information can be used by the server to choose the best TLS version o use.

Parameters

c – The connection.
is_client – True if event is raised for the client side of the connection (the side that sends the client hello). This is typically equivalent with the originator, but does not have to be in all circumstances.
versions – List of supported TLS versions.

ssl_handshake_message 

Type: event (c: connection, is_client: bool, msg_type: count, length: count)

This event is raised for each unencrypted SSL/TLS handshake message.

Parameters

c – The connection.
is_client – True if event is raised for the client side of the connection (the side that sends the client hello). This is typically equivalent with the originator, but does not have to be in all circumstances.
msg_type – Type of the handshake message that was seen.
length – Length of the handshake message that was seen.

ssl_heartbeat

Type: event (c: connection, is_client: bool, length: count, heartbeat_type: count, payload_length: count, payload: string)

Generated for SSL/TLS heartbeat messages that are sent before session encryption starts. Generally heartbeat messages should rarely be seen in normal TLS traffic. Heartbeats are described in RFC 6520.

Parameters

c – The connection.
is_client – True if event is raised for the client side of the connection (the side that sends the client hello). This is typically equivalent with the originator, but does not have to be in all circumstances.
length – length of the entire heartbeat message.
heartbeat_type – type of the heartbeat message. Per RFC, 1 = request, 2 = response.
payload_length – length of the payload of the heartbeat message, according to packet field.
payload – payload contained in the heartbeat message. Size can differ from payload_length, if payload_length and actual packet length disagree.

ssl_plaintext_data 

Type: event (c: connection, is_client: bool, record_version: count, content_type: count, length: count)

Generated for SSL/TLS messages that are sent before full session encryption starts. Note that “full encryption” is a bit fuzzy, especially for TLSv1.3; here this event will be raised for early packets that are already using pre-encryption. # This event is also used by Zeek internally to determine if the connection has been completely setup. This is necessary as TLS 1.3 does not have CCS anymore.

Parameters

c – The connection.
is_client – True if event is raised for the client side of the connection (the side that sends the client hello). This is typically equivalent with the originator, but does not have to be in all circumstances.
record_version – TLS version given in the record layer of the message. Set to 0 for SSLv2.
content_type – message type as reported by TLS session layer. Not populated for SSLv2.
length – length of the entire message.

ssl_probable_encrypted_handshake_message

Type: event (c: connection, is_client: bool, length: count)

This event is generated for application data records of TLS 1.3 connections of which we suspect that they contain handshake messages.

In TLS 1.3, large parts of the handshake are encrypted; the only cleartext packets typically exchanged are the client hello and the server hello. The first few packets after the client and server hello, however, are a continuation of the handshake and still include handshake data.

This event is raised for these packets of which we suspect that they are handshake records, including the finished record.

The heuristic for this is: all application data record after the server hello are handshake records until at least one application data record has been received from both the server and the client. Typically, the server will send more records before the client sends the first application data record; and the first application data record of the client will typically include the finished message.

Given the encrypted nature of the protocol, in some cases this determination is not correct; the client can send more handshake packets before the finished message, e.g., when client certificates are used.

Note that :zeek:see::ssl_encrypted_data is also raised for these messages.

Parameters

c – The connection.
is_client – True if event is raised for the client side of the connection (the side that sends the client hello). This is typically equivalent with the originator, but does not have to be in all circumstances.
length – length of the entire message.

ssl_rsa_client_pms

Type: event (c: connection, pms: string)

Generated if a client uses RSA key exchange. This event contains the client encrypted pre-master secret which is encrypted using the public key of the server’s certificate as defined in RFC 5246.

Parameters

c – The connection.
pms – The encrypted pre-master secret.

ssl_server_hello

Type: event (c: connection, version: count, record_version: count, possible_ts: time, server_random: string, session_id: string, cipher: count, comp_method: count)

Generated for an SSL/TLS server’s initial hello message. SSL/TLS sessions start with an unencrypted handshake, and Zeek extracts as much information out of that as it can. This event provides access to the initial information sent by the client.

See Wikipedia for more information about the SSL/TLS protocol.

Parameters

c – The connection.
version – The protocol version as extracted from the server’s message. The values are standardized as part of the SSL/TLS protocol. The SSL::version_strings table maps them to descriptive names.
record_version – TLS version given in the record layer of the message. Set to 0 for SSLv2.
possible_ts – The current time as sent by the server. Note that SSL/TLS does not require clocks to be set correctly, so treat with care. This value is meaningless in SSLv2 and TLSv1.3.
session_id – The session ID as sent back by the server (if any). This value is not sent in TLSv1.3.
server_random – The random value sent by the server. For version 2 connections, the connection-id is returned. Note - the full 32 bytes are included in server_random. This means that the 4 bytes present in possible_ts are repeated; if you do not want this behavior ignore the first 4 bytes.
cipher – The cipher chosen by the server. The values are standardized as part of the SSL/TLS protocol. The SSL::cipher_desc table maps them to descriptive names.
comp_method – The compression method chosen by the client. The values are standardized as part of the SSL/TLS protocol. This value is not sent in TLSv1.3 or SSLv2.

ssl_server_signature

Type: event (c: connection, signature_and_hashalgorithm: SSL::SignatureAndHashAlgorithm, signature: string)

Generated if a server uses a non-anonymous DHE or ECDHE cipher suite. This event contains the server signature over the key exchange parameters contained in the ServerKeyExchange message as defined in RFC 4492 and RFC 5246.

Parameters

c – The connection.
signature_and_hashalgorithm – signature and hash algorithm used for the digitally_signed struct. This field is only present starting with TLSv1.2 and DTLSv1.2. Earlier versions used a hardcoded hash algorithm. For protocol versions below D(TLS)v1.2 this field is filled with an dummy value of 256.
signature – Signature part of the digitally_signed struct. The private key corresponding to the certified public key in the server’s certificate message is used for signing.

ssl_session_ticket_handshake 

Type: event (c: connection, ticket_lifetime_hint: count, ticket: string)

Generated for SSL/TLS handshake messages that are a part of the stateless-server session resumption mechanism. SSL/TLS sessions start with an unencrypted handshake, and Zeek extracts as much information out of that as it can. This event is raised when an SSL/TLS server passes a session ticket to the client that can later be used for resuming the session. The mechanism is described in RFC 4507.

See Wikipedia for more information about the SSL/TLS protocol.

Parameters

c – The connection.
ticket_lifetime_hint – A hint from the server about how long the ticket should be stored by the client.
ticket – The raw ticket data.

ssl_stapled_ocsp 

Type: event (c: connection, is_client: bool, response: string)

This event contains the OCSP response contained in a Certificate Status Request message, when the client requested OCSP stapling and the server supports it. See description in RFC 6066.

Parameters

c – The connection.
is_client – True if event is raised for the client side of the connection (the side that sends the client hello). This is typically equivalent with the originator, but does not have to be in all circumstances.
response – OCSP data.