policy/protocols/ssl/weak-keys.bro

SSL

Generate notices when SSL/TLS connections use certificates, DH parameters, or cipher suites that are deemed to be insecure.

Namespace:SSL Imports:base/frameworks/notice, base/protocols/ssl, base/utils/directions-and-hosts.bro Source File:/scripts/policy/protocols/ssl/weak-keys.bro

Summary

Runtime Options

SSL::notify_dh_length_shorter_cert_length: bool &redef	Warn if the DH key length is smaller than the certificate key length.
SSL::notify_minimal_key_length: count &redef	The minimal key length in bits that is considered to be safe.
SSL::notify_weak_keys: Host &redef	The category of hosts you would like to be notified about which are using weak keys/ciphers/protocol_versions.
SSL::tls_minimum_version: count &redef	Warn if a server negotiates a SSL session with a protocol version smaller than the specified version.
SSL::unsafe_ciphers_regex: pattern &redef	Warn if a server negotiates an unsafe cipher suite.

Redefinitions

Notice::Type: enum

Detailed Interface

Runtime Options

SSL::notify_dh_length_shorter_cert_length

Type:bool Attributes:&redef Default:T

Warn if the DH key length is smaller than the certificate key length. This is potentially unsafe because it gives a wrong impression of safety due to the certificate key length. However, it is very common and cannot be avoided in some settings (e.g. with old jave clients).

SSL::notify_minimal_key_length

Type:count Attributes:&redef Default:2048

The minimal key length in bits that is considered to be safe. Any shorter (non-EC) key lengths will trigger a notice.

SSL::notify_weak_keys

Type:Host Attributes:&redef Default:LOCAL_HOSTS

The category of hosts you would like to be notified about which are using weak keys/ciphers/protocol_versions. By default, these notices will be suppressed by the notice framework for 1 day after a particular host has had a notice generated. Choices are: LOCAL_HOSTS, REMOTE_HOSTS, ALL_HOSTS, NO_HOSTS

SSL::tls_minimum_version

Type:count Attributes:&redef Default:769

Warn if a server negotiates a SSL session with a protocol version smaller than the specified version. By default, the minimal version is TLSv10 because SSLv2 and v3 have serious security issued. See https://tools.ietf.org/html/draft-thomson-sslv3-diediedie-00 To disable, set to SSLv20

SSL::unsafe_ciphers_regex

Type:pattern Attributes:&redef Default:

/^?((_EXPORT_)|(_RC4_))$?/

Warn if a server negotiates an unsafe cipher suite. By default, we only warn when encountering old export cipher suites, or RC4 (see RFC7465).