NAME¶

HashBL - query hashed (and unhashed) DNS blocklists

SYNOPSIS¶

  loadplugin Mail::SpamAssassin::Plugin::HashBL
  # NON-WORKING usage examples below, replace xxx.example.invalid with real list
  # See documentation below for detailed usage
  header   HASHBL_EMAIL eval:check_hashbl_emails('ebl.example.invalid')
  describe HASHBL_EMAIL Message contains email address found on EBL
  tflags   HASHBL_EMAIL net
  # rewrite googlemail.com -> gmail.com, applied before acl/welcomelist
  hashbl_email_domain_alias gmail.com googlemail.com
  # only query gmail.com addresses
  hashbl_acl_freemail gmail.com
  header   HASHBL_OSENDR eval:check_hashbl_emails('rbl.example.invalid/A', 'md5/max=10/shuffle', 'X-Original-Sender', '^127\.', 'freemail')
  describe HASHBL_OSENDR Message contains email address found on HASHBL
  tflags   HASHBL_OSENDR net
  body     HASHBL_BTC eval:check_hashbl_bodyre('btcbl.example.invalid', 'sha1/max=10/shuffle', '\b([13][a-km-zA-HJ-NP-Z1-9]{25,34})\b')
  describe HASHBL_BTC Message contains BTC address found on BTCBL
  tflags   HASHBL_BTC net
  header   HASHBL_URI eval:check_hashbl_uris('rbl.example.invalid', 'sha1', '^127\.0\.0\.32$')
  describe HASHBL_URI Message contains uri found on rbl
  tflags   HASHBL_URI net
  body     HASHBL_ATTACHMENT eval:check_hashbl_attachments('attbl.example.invalid', 'sha256')
  describe HASHBL_ATTACHMENT Message contains attachment found on attbl
  tflags   HASHBL_ATTACHMENT net
  # Capture tag using SA 4.0 regex named capture feature
  header   __X_SOME_ID X-Some-ID =~ /^(?<XSOMEID>\d{10,20})$/
  # Query the tag value as is from a DNSBL
  header   HASHBL_TAG eval:check_hashbl_tag('idbl.example.invalid/A', 'raw', 'XSOMEID', '^127\.')

DESCRIPTION¶

This plugin supports multiple types of hashed or unhashed DNS blocklist queries.

Common OPTS that apply to all functions:

  raw      no hashing, query as is (can break if value is not valid DNS label)
  md5      hash query with MD5
  sha1     hash query with SHA1
  sha256   hash query with Base32 encoded SHA256
  case     keep case before hashing, default is to lowercase
  max=x    maximum number of queries (defaults to 10 if not specified)
  shuffle  if max exceeded, random shuffle queries before truncating to limit
    

Multiple options can be separated with slash.

When rule OPTS is empty ('') or missing, default is used as documented by each query type. If any options are defined, then all needed options must be explicitly defined.

header RULE check_hashbl_emails('bl.example.invalid/A', 'OPTS', 'HEADERS', '^127\.')

Check email addresses from DNS list. Note that "body" can be specified along with headers to search message body for emails. Rule type must always be "header".

Optional DNS query type can be appended to list with /A (default) or /TXT.

Default OPTS: sha1/notag/noquote/max=10/shuffle

Additional supported OPTS:

  nodot    strip username dots from email
  notag    strip username tags from email
  nouri    ignore emails inside uris
  noquote  ignore emails inside < > or possible quotings
  user     query userpart of email only
  host     query hostpart of email only
  domain   query domain of email only (hostpart+trim_domain)
    

Default HEADERS: ALLFROM/Reply-To/body

HEADERS refers to slash separated list of Headers to process:

  ALL           all headers
  ALLFROM       all From headers as returned by $pms->all_from_addrs()
  EnvelopeFrom  message envelope from (Return-Path etc)
  <HeaderName>  any header as used with header rules or $pms->get()
  body          all emails found in message body
    

If HEADERS is empty ('') or missing, default is used.

Optional subtest regexp to match DNS answer (default: '^127\.').

For existing public email blocklist, see: http://msbl.org/ebl.html

  # Working example, see https://msbl.org/ebl.html before usage
  header   HASHBL_EMAIL eval:check_hashbl_emails('ebl.msbl.org')
  describe HASHBL_EMAIL Message contains email address found on EBL
  tflags   HASHBL_EMAIL net
    

Default regex for matching and capturing emails can be overridden with "hashbl_email_regex". Likewise, the default welcomelist can be changed with "hashbl_email_welcomelist". Only change if you know what you are doing, see plugin source code for the defaults. Example: hashbl_email_regex \S+@\S+.com

header RULE check_hashbl_uris('bl.example.invalid/A', 'OPTS', '^127\.')

Check all URIs parsed from message from DNS list.

Optional DNS query type can be appended to list with /A (default) or /TXT.

Default OPTS: sha1/max=10/shuffle

Optional subtest regexp to match DNS answer (default: '^127\.').

[raw]body RULE check_hashbl_bodyre('bl.example.invalid/A', 'OPTS', '\b(match)\b', '^127\.')

Search body for matching regexp and query the string captured. Regexp must have a single capture ( ) for the string ($1). Rule type must be "body" or "rawbody".

Optional DNS query type can be appended to list with /A (default) or /TXT.

Default OPTS: sha1/max=10/shuffle

Additional supported OPTS:

  num      remove the chars from the match that are not numbers
    

Optional subtest regexp to match DNS answer (default: '^127\.').

header RULE check_hashbl_tag('bl.example.invalid/A', 'OPTS', 'TAGNAME', '^127\.')

Query value of SpamAssassin tag _TAGNAME_ from DNS list.

Optional DNS query type can be appended to list with /A (default) or /TXT.

Default OPTS: sha1/max=10/shuffle

Additional supported OPTS:

  ip        only query if value is valid IPv4/IPv6 address
  ipv4      only query if value is valid IPv4 address
  ipv6      only query if value is valid IPv6 address
  revip     reverse IP before query
  fqdn      only query if value is valid FQDN (is_fqdn_valid)
  tld       only query if value has valid TLD (is_domain_valid)
  trim      trim name from hostname to domain (trim_domain)
  If both ip/ipv4/ipv6 and fqdn/tld are enabled, only either of them is
  required to match.  Both fqdn and tld are needed for complete FQDN+TLD
  check.
    

Optional subtest regexp to match DNS answer (default: '^127\.').

header RULE check_hashbl_attachments('bl.example.invalid/A', 'OPTS', '^127\.')

Check all all message attachments (mimeparts) from DNS list.

Optional DNS query type can be appended to list with /A (default) or /TXT.

Default OPTS: sha1/max=10/shuffle

Additional supported OPTS:

  minsize=x  skip any parts smaller than x bytes
  maxsize=x  skip any parts larger than x bytes
    

Optional subtest regexp to match DNS answer (default: '^127\.').

Specific attachment filenames can be skipped with "hashbl_ignore". For example "hashbl_ignore safe.pdf".

Specific mime types can be skipped with "hashbl_ignore". For example "hashbl_ignore text/plain".

hashbl_ignore value [value...]

Skip any type of query, if either the hash or original value (email for example) matches. Multiple values can be defined, separated by whitespace. Matching is case-insensitive.

Any host or its domain part matching uridnsbl_skip_domains is also ignored by default.