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Google says it recently fixed an authentication weakness that allowed crooks to circumvent the email verification required to create a Google Workspace account, and leverage that to impersonate a domain holder at third-party services that allow logins through Google’s “Sign in with Google” feature.
Last week, KrebsOnSecurity heard from a reader who said they received a notice that their email address had been used to create a potentially malicious Workspace account that Google had blocked.
“In the last few weeks, we identified a small-scale abuse campaign whereby bad actors circumvented the email verification step in our account creation flow for Email Verified (EV) Google Workspace accounts using a specially constructed request,” the notice from Google read. “These EV users could then be used to gain access to third-party applications using ‘Sign In with Google’.”
In response to questions, Google said it fixed the problem within 72 hours of discovering it, and that the company has added additional detection to protect against these types of authentication bypasses going forward.
Anu Yamunan, director of abuse and safety protections at Google Workspace, told KrebsOnSecurity the malicious activity began in late June, and involved “a few thousand” Workspace accounts that were created without being domain-verified.
Google Workspace offers a free trial that people can use to access services like Google Docs, but other services such as Gmail are only available to Workspace users who can validate control over the domain name associated with their email address. The weakness Google fixed allowed attackers to bypass this validation process. Google emphasized that none of the affected domains had previously been associated with Workspace accounts or services.
“The tactic here was to create a specifically-constructed request by a bad actor to circumvent email verification during the signup process,” Yamunan said. “The vector here is they would use one email address to try to sign in, and a completely different email address to verify a token. Once they were email verified, in some cases we have seen them access third party services using Google single sign-on.”
Yamunan said none of the potentially malicious workspace accounts were used to abuse Google services, but rather the attackers sought to impersonate the domain holder to other services online.
In the case of the reader who shared the breach notice from Google, the imposters used the authentication bypass to associate his domain with a Workspace account. And that domain was tied to his login at several third-party services online. Indeed, the alert this reader received from Google said the unauthorized Workspace account appears to have been used to sign in to his account at Dropbox.
Google said the now-fixed authentication bypass is unrelated to a recent issue involving cryptocurrency-based domain names that were apparently compromised in their transition to Squarespace, which last year acquired more than 10 million domains that were registered via Google Domains.
On July 12, a number of domains tied to cryptocurrency businesses were hijacked from Squarespace users who hadn’t yet set up their Squarespace accounts. Squarespace has since published a statement blaming the domain hijacks on “a weakness related to OAuth logins”, which Squarespace said it fixed within hours.
A Slack Attack Framework for conducting Red Team and phishing exercises within Slack workspaces.
This tool is intended for Security Professionals only. Do not use this tool against any Slack workspace without explicit permission to test. Use at your own risk.
Thousands of organizations utilize Slack to help their employees communicate, collaborate, and interact. Many of these Slack workspaces install apps or bots that can be used to automate different tasks within Slack. These bots are individually provided permissions that dictate what tasks the bot is permitted to request via the Slack API. To authenticate to the Slack API, each bot is assigned an api token that begins with xoxb or xoxp. More often than not, these tokens are leaked somewhere. When these tokens are exfiltrated during a Red Team exercise, it can be a pain to properly utilize them. Now EvilSlackbot is here to automate and streamline that process. You can use EvilSlackbot to send spoofed Slack messages, phishing links, files, and search for secrets leaked in slack.
In addition to red teaming, EvilSlackbot has also been developed with Slack phishing simulations in mind. To use EvilSlackbot to conduct a Slack phishing exercise, simply create a bot within Slack, give your bot the permissions required for your intended test, and provide EvilSlackbot with a list of emails of employees you would like to test with simulated phishes (Links, files, spoofed messages)
EvilSlackbot requires python3 and Slackclient
FreshRSS 
pip3 install slackclient
usage: EvilSlackbot.py [-h] -t TOKEN [-sP] [-m] [-s] [-a] [-f FILE] [-e EMAIL]
[-cH CHANNEL] [-eL EMAIL_LIST] [-c] [-o OUTFILE] [-cL]
options:
-h, --help show this help message and exit
Required:
-t TOKEN, --token TOKEN
Slack Oauth token
Attacks:
-sP, --spoof Spoof a Slack message, customizing your name, icon, etc
(Requires -e,-eL, or -cH)
-m, --message Send a message as the bot associated with your token
(Requires -e,-eL, or -cH)
-s, --search Search slack for secrets with a keyword
-a, --attach Send a message containing a malicious attachment (Requires -f
and -e,-eL, or -cH)
Arguments:
-f FILE, --file FILE Path to file attachment
-e EMAIL, --email EMAIL
Email of target
-cH CHANNEL, --channel CHANNEL
Target Slack Channel (Do not include #)
-eL EMAIL_LIST, --email_list EMAIL_LIST
Path to list of emails separated by newline
-c, --check Lookup and display the permissions and available attacks
associated with your provided token.
-o OUTFILE, --outfile OUTFILE
Outfile to store search results
-cL, --channel_list List all public Slack channels
To use this tool, you must provide a xoxb or xoxp token.
Required:
-t TOKEN, --token TOKEN (Slack xoxb/xoxp token)
python3 EvilSlackbot.py -t <token>
Depending on the permissions associated with your token, there are several attacks that EvilSlackbot can conduct. EvilSlackbot will automatically check what permissions your token has and will display them and any attack that you are able to perform with your given token.
Attacks:
-sP, --spoof Spoof a Slack message, customizing your name, icon, etc (Requires -e,-eL, or -cH)
-m, --message Send a message as the bot associated with your token (Requires -e,-eL, or -cH)
-s, --search Search slack for secrets with a keyword
-a, --attach Send a message containing a malicious attachment (Requires -f and -e,-eL, or -cH)
With the correct token permissions, EvilSlackbot allows you to send phishing messages while impersonating the botname and bot photo. This attack also requires either the email address (-e) of the target, a list of target emails (-eL), or the name of a Slack channel (-cH). EvilSlackbot will use these arguments to lookup the SlackID of the user associated with the provided emails or channel name. To automate your attack, use a list of emails.
python3 EvilSlackbot.py -t <xoxb token> -sP -e <email address>
python3 EvilSlackbot.py -t <xoxb token> -sP -eL <email list>
python3 EvilSlackbot.py -t <xoxb token> -sP -cH <Channel name>
With the correct token permissions, EvilSlackbot allows you to send phishing messages containing phishing links. What makes this attack different from the Spoofed attack is that this method will send the message as the bot associated with your provided token. You will not be able to choose the name or image of the bot sending your phish. This attack also requires either the email address (-e) of the target, a list of target emails (-eL), or the name of a Slack channel (-cH). EvilSlackbot will use these arguments to lookup the SlackID of the user associated with the provided emails or channel name. To automate your attack, use a list of emails.
python3 EvilSlackbot.py -t <xoxb token> -m -e <email address>
python3 EvilSlackbot.py -t <xoxb token> -m -eL <email list>
python3 EvilSlackbot.py -t <xoxb token> -m -cH <Channel name>
With the correct token permissions, EvilSlackbot allows you to search Slack for secrets via a keyword search. Right now, this attack requires a xoxp token, as xoxb tokens can not be given the proper permissions to keyword search within Slack. Use the -o argument to write the search results to an outfile.
python3 EvilSlackbot.py -t <xoxp token> -s -o <outfile.txt>
With the correct token permissions, EvilSlackbot allows you to send file attachments. The attachment attack requires a path to the file (-f) you wish to send. This attack also requires either the email address (-e) of the target, a list of target emails (-eL), or the name of a Slack channel (-cH). EvilSlackbot will use these arguments to lookup the SlackID of the user associated with the provided emails or channel name. To automate your attack, use a list of emails.
python3 EvilSlackbot.py -t <xoxb token> -a -f <path to file> -e <email address>
python3 EvilSlackbot.py -t <xoxb token> -a -f <path to file> -eL <email list>
python3 EvilSlackbot.py -t <xoxb token> -a -f <path to file> -cH <Channel name>
Arguments:
-f FILE, --file FILE Path to file attachment
-e EMAIL, --email EMAIL Email of target
-cH CHANNEL, --channel CHANNEL Target Slack Channel (Do not include #)
-eL EMAIL_LIST, --email_list EMAIL_LIST Path to list of emails separated by newline
-c, --check Lookup and display the permissions and available attacks associated with your provided token.
-o OUTFILE, --outfile OUTFILE Outfile to store search results
-cL, --channel_list List all public Slack channels
With the correct permissions, EvilSlackbot can search for and list all of the public channels within the Slack workspace. This can help with planning where to send channel messages. Use -o to write the list to an outfile.
python3 EvilSlackbot.py -t <xoxb token> -cL
T3SF is a framework that offers a modular structure for the orchestration of events based on a master scenario events list (MSEL) together with a set of rules defined for each exercise (optional) and a configuration that allows defining the parameters of the corresponding platform. The main module performs the communication with the specific module (Discord, Slack, Telegram, etc.) that allows the events to present the events in the input channels as injects for each platform. In addition, the framework supports different use cases: "single organization, multiple areas", "multiple organization, single area" and "multiple organization, multiple areas".
To use the framework with your desired platform, whether it's Slack or Discord, you will need to install the required modules for that platform. But don't worry, installing these modules is easy and straightforward.
To do this, you can follow this simple step-by-step guide, or if you're already comfortable installing packages with pip, you can skip to the last step!
# Python 3.6+ required
python -m venv .venv # We will create a python virtual environment
source .venv/bin/activate # Let's get inside it
pip install -U pip # Upgrade pipOnce you have created a Python virtual environment and activated it, you can install the T3SF framework for your desired platform by running the following command:
pip install "T3SF[Discord]" # Install the framework to work with Discordor
pip install "T3SF[Slack]" # Install the framework to work with SlackThis will install the T3SF framework along with the required dependencies for your chosen platform. Once the installation is complete, you can start using the framework with your platform of choice.
We strongly recommend following the platform-specific guidance within our Read The Docs! Here are the links:
We created this framework to simplify all your work!
$ docker run --rm -t --env-file .env -v $(pwd)/MSEL.json:/app/MSEL.json base4sec/t3sf:slackInside your .env file you have to provide the SLACK_BOT_TOKEN and SLACK_APP_TOKEN tokens. Read more about it here.
There is another environment variable to set, MSEL_PATH. This variable tells the framework in which path the MSEL is located. By default, the container path is /app/MSEL.json. If you change the mount location of the volume then also change the variable.
$ docker run --rm -t --env-file .env -v $(pwd)/MSEL.json:/app/MSEL.json base4sec/t3sf:discordInside your .env file you have to provide the DISCORD_TOKEN token. Read more about it here.
There is another environment variable to set, MSEL_PATH. This variable tells the framework in which path the MSEL is located. By default, the container path is /app/MSEL.json. If you change the mount location of the volume then also change the variable.
Once you have everything ready, use our template for the main.py, or modify the following code:
Here is an example if you want to run the framework with the Discord bot and a GUI.
from T3SF import T3SF
import asyncio
async def main():
await T3SF.start(MSEL="MSEL_TTX.json", platform="Discord", gui=True)
if __name__ == '__main__':
asyncio.run(main())Or if you prefer to run the framework without GUI and with Slack instead, you can modify the arguments, and that's it!
Yes, that simple!
await T3SF.start(MSEL="MSEL_TTX.json", platform="Slack", gui=False)If you need more help, you can always check our documentation here!
