Monitoring and enumerating Slack for exposed secrets
Slack Watchman is an application that uses the Slack API to find potentially sensitive data exposed in a Slack workspace, and to enumerate other useful information for red, blue and purple teams.
More information about Slack Watchman can be found on my blog.
Slack Watchman looks for:
- API Keys, Tokens & Service Accounts
- AWS, Azure, GCP, Google API, Slack (keys & webhooks), Twitter, Facebook, GitHub and more
- Generic Private keys
- Access Tokens, Bearer Tokens, Client Secrets, Private Tokens
- Files
- Certificate files
- Potentially interesting/malicious/sensitive files (.docm, .xlsm, .zip etc.)
- Executable files
- Keychain files
- Config files for popular services (Terraform, Jenkins, OpenVPN and more)
- Personal Data
- Leaked passwords
- Passport numbers, Dates of birth, Social security numbers, National insurance numbers and more
- Financial data
- Paypal Braintree tokens, Bank card details, IBAN numbers, CUSIP numbers and more
You can run Slack Watchman to look for results going back as far as:
- 24 hours
- 7 days
- 30 days
- All time
It also enumerates the following:
- User data
- All users & all admins
- Conversation data
- All conversations, including externally shared conversations
- All conversations that include a Slack Canvas (which often contain sensitive or important information)
- Workspace authentication options
This means after one deep scan, you can schedule Slack Watchman to run regularly and only return results from your chosen timeframe.
You can run Slack Watchman in unauthenticated probe mode to enumerate authentication options and other information on a Workspace. This doesn't need a token, and returns:
- Workspace name
- Workspace ID
- Approved domains (which can create accounts)
- OAuth providers
- SSO auth status
- Two-factor requirements
To run this mode use Slack Watchman with the --probe flag and the workspace domain to probe:
slack-watchman --probe https://domain.slack.com
Slack Watchman uses custom YAML signatures to detect matches in Slack. These signatures are pulled from the central Watchman Signatures repository. Slack Watchman automatically updates its signature base at runtime to ensure its using the latest signatures to detect secrets.
You can define signatures that you want to disable when running Slack Watchman by adding their IDs to the disabled_signatures section of the watchman.conf file. For example:
slack_watchman:
token: ...
cookie: ...
url: ...
disabled_signatures:
- tokens_generic_bearer_tokens
- tokens_generic_access_tokensYou can find the ID of a signature in the individual YAML files in Watchman Signatures repository.
Slack Watchman gives the following logging options:
- Terminal-friendly Stdout
- JSON to Stdout
Slack Watchman defaults to terminal-friendly stdout logging if no option is given. This is designed to be easier for humans to read.
JSON logging is also available, which is perfect for ingesting into a SIEM or other log analysis platforms.
JSON formatted logging can be easily redirected to a file as below:
slack-watchman --timeframe a --all --output json >> slack_watchman_log.json
To run Slack Watchman, you will need a Slack API OAuth access token. You can do this by creating a simple Slack App.
The app needs to have the following User Token Scopes added:
channels:read
files:read
groups:read
im:read
links:read
mpim:read
remote_files:read
search:read
team:read
users:read
users:read.email
Note: User tokens act on behalf of the user who authorises them, so I would suggest you create this app and authorise it using a service account, otherwise the app will have access to your private conversations and chats.
Slack apps can be created from JSON manifests which define the details of the application and the scopes to approve. The app manifest for Slack Watchman can be found in docs/app_manifest.json, you can use this to speed up creating your Slack app.
Alternatively, Slack Watchman can also authenticate to Slack using a user d cookie, which is stored in the browser of each user logged into a workspace.
To use cookie authentication, you will need to provide the d cookie, and the URL of the target workspace. Then you will need to use the --cookie flag when running Slack Watchman
More information on cookie authentication can be found on my blog
Slack Watchman will first try to get the Slack token (plus the cookie token and URL if selected) from the environment variables
SLACK_WATCHMAN_TOKENSLACK_WATCHMAN_COOKIESLACK_WATCHMAN_URL
If this fails it will try to load the token(s) from .conf file (see below).
Configuration options can be passed in a file named watchman.conf which must be stored in your home directory. The file should follow the YAML format, and should look like below:
slack_watchman:
token: xoxp-xxxxxxxx
cookie: xoxd-%2xxxxx
url: https://xxxxx.slack.com
disabled_signatures:
- tokens_generic_bearer_tokens
- tokens_generic_access_tokensSlack Watchman will look for this file at runtime, and use the configuration options from here. If you are not using cookie auth, leave cookie and url blank.
If you are having issues with your .conf file, run it through a YAML linter.
An example file is in docs/example.conf
Note: Cookie and URL values are optional, and not required if not using cookie authentication.
You can install the latest stable version via pip:
python3 -m pip install slack-watchman
Or build from source yourself:
Download the release source files, then from the top level repository run:
python3 -m pip build
python3 -m pip install --force-reinstall dist/*.whl
Slack Watchman is also available from the Docker hub as a Docker image:
docker pull papermountain/slack-watchman:latest
You can then run Slack Watchman in a container, making sure you pass the required environment variables:
// help
docker run --rm papermountain/slack-watchman -h
// scan all
docker run --rm -e SLACK_WATCHMAN_TOKEN=xoxp... papermountain/slack-watchman --timeframe a --all --output json
docker run --rm --env-file .env papermountain/slack-watchman --timeframe a --all --output stdout
Slack Watchman will be installed as a global command, use as follows:
usage: slack-watchman [-h] [--timeframe {d,w,m,a}] [--output {json,stdout}] [--version] [--all] [--users] [--channels] [--pii] [--secrets] [--debug] [--verbose] [--cookie] [--probe PROBE_DOMAIN]
Monitoring and enumerating Slack for exposed secrets
options:
-h, --help show this help message and exit
--timeframe {d,w,m,a}, -t {d,w,m,a}
How far back to search: d = 24 hours w = 7 days, m = 30 days, a = all time
--output {json,stdout}, -o {json,stdout}
Where to send results
--version, -v show program's version number and exit
--all, -a Find secrets and PII
--users, -u Enumerate users and output them to .csv in the current working directory
--channels, -c Enumerate channels and output them to .csv in the current working directory
--pii, -p Find personal data: DOB, passport details, drivers licence, ITIN, SSN etc.
--secrets, -s Find exposed secrets: credentials, tokens etc.
--debug, -d Turn on debug level logging
--verbose, -V Turn on more verbose output for JSON logging. This includes more fields, but is larger
--cookie Use cookie auth using Slack d cookie. REQUIRES either SLACK_WATCHMAN_COOKIE and SLACK_WATCHMAN_URL environment variables set, or both values set in watchman.conf
--probe PROBE_DOMAIN Perform an un-authenticated probe on a workspace for available authentication options and other information. Enter workspace domain to probe
You can run Slack Watchman to look for everything, and output to default stdout:
slack-watchman --timeframe a --all
You may be interested in the other apps in the Watchman family:
The source code for this project is released under the GNU General Public Licence. This project is not associated with Slack Technologies or Salesforce.
