weak-keys.zeek

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.zeek

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

SSL::Old_Version: Indicates that a server is using a potentially unsafe version
SSL::Weak_Cipher: Indicates that a server is using a potentially unsafe cipher
SSL::Weak_Key: Indicates that a server is using a potentially unsafe key.

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 java 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).