kachi

Make a protected link unsafe.

Requirements

• Python 3.10+

Installation

pip install kachi

Usage

from kachi import unsafe_link

result = unsafe_link("https://nam01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fexample.com")
print(result)  # https://example.com

Bundled Rules

Rule	Service
azure_email	Azure Email Safe Links
barracuda	Barracuda Link Protect
esvalabs	EsvaLabs URL Sandbox
fireeye	FireEye URL Defense
o365_safelinks	Microsoft 365 Safe Links
proofpoint_v1	Proofpoint URL Defense v1
proofpoint_v2	Proofpoint URL Defense v2
ses_awstrack	AWS SES Click Tracking
sophos	Sophos Email Protection
trendmicro	Trend Micro Email Security
urldefense_v3	Proofpoint URL Defense v3
whatsapp	WhatsApp Link Redirect

Rule Schema

Each rule is a YAML file with the following structure:

name: example_rule
filter:
  hostname: example.com # exact match, or /regex/
  path: /redirect # optional, exact match or /regex/
pre_extract: # optional, transforms applied to URL before extraction
  - html_unescape
  - url_decode
extract:
  from: query_param # query_param, path_regex, or url_regex
  keys: [url, u] # for query_param: parameter names to try in order
  pattern: "/L0/(http[^/?#]+)" # for path_regex/url_regex: regex with capture group
  select: first # for query_param: first (default) or last
post_extract: # optional, transforms applied to extracted value
  - url_decode

Filter

• hostname (required): string or list of strings. Exact match or /regex/.
• path (optional): string or list of strings. Exact match or /regex/.

Extract Sources

Source	Description
query_param	Extract from URL query parameters. Requires keys.
path_regex	Match regex against URL path. Requires pattern with a capture group.
url_regex	Match regex against full URL. Requires pattern with a capture group.

Transforms

Name	Description
html_unescape	Decode HTML entities (& -> &)
url_decode	Percent-decode (%2F -> /)
base64_decode	Base64 decode
prepend	Prepend a string (requires a value, e.g. {prepend: "http://"})
proofpoint_v2_decode	Decode Proofpoint v2 URL encoding