command_and_control-GC2-Tool.md

GC2 experimental detection for hosts communicating with possible C2 server using the GC2 framework

Source:

• https://github.com/looCiprian/GC2-sheet

GC2

Tactic: Comand and Contol

Source:

• https://github.com/looCiprian/GC2-sheet/
• https://www.youtube.com/watch?v=n2dFlSaBBKo
• https://services.google.com/fh/files/blogs/gcat_threathorizons_full_apr2023.pdf
• https://www.tanium.com/blog/apt41-deploys-google-gc2-for-attacks-cyber-threat-intelligence-roundup/
• https://www.bleepingcomputer.com/news/security/hackers-abuse-google-command-and-control-red-team-tool-in-attacks/

MDE Kusto

//Processes interacting with Google Sheets (Has been known to be used for C2 communication) 
// https://github.com/looCiprian/GC2-sheet
//false positives - browsers going to the URL. Or a legitimate application that uses Google Sheets 
let excludedProcessFileNames = datatable (browser:string)["teams.exe","GoogleUpdate.exe","outlook.exe","msedge.exe","chrome.exe","iexplorer.exe","brave.exe","firefox.exe"]; //add more browsers or mail clients where needed for exclusion 
DeviceNetworkEvents 
| where not(InitiatingProcessFileName has_any (excludedProcessFileNames))
| where RemoteUrl has_any ("oauth2.googleapis.com","sheets.googleapis.com","drive.googleapis.com","www.googleapis.com") and isnotempty(InitiatingProcessFileName)
| summarize visitedURLs=make_list(RemoteUrl) by ActionType, DeviceName, InitiatingProcessAccountName, InitiatingProcessParentFileName, InitiatingProcessFileName
| project ActionType, DeviceName, InitiatingProcessAccountName, InitiatingProcessParentFileName, InitiatingProcessFileName, visitedURLs, Connections=array_length(visitedURLs)
| where visitedURLs contains "oauth2.googleapis.com" and visitedURLs has_any ("sheets.googleapis.com","drive.googleapis.com") // may allow for higher fidelity as the GC2 go application communicates to both the google drive folder and sheets API.

Sentinel Kusto

//Processes interacting with Google Sheets (Has been known to be used for C2 communication) 
// https://github.com/looCiprian/GC2-sheet
//false positives - browsers going to the URL. Or a legitimate application that uses Google Sheets 
let excludedProcessFileNames = datatable (browser:string)["teams.exe","GoogleUpdate.exe","outlook.exe","msedge.exe","chrome.exe","iexplorer.exe","brave.exe","firefox.exe"]; //add more browsers or mail clients where needed for exclusion 
DeviceNetworkEvents 
| where not(InitiatingProcessFileName has_any (excludedProcessFileNames))
| where RemoteUrl has_any ("oauth2.googleapis.com","sheets.googleapis.com","drive.googleapis.com","www.googleapis.com") and isnotempty(InitiatingProcessFileName)
| summarize visitedURLs=make_list(RemoteUrl) by ActionType, DeviceName, InitiatingProcessAccountName, InitiatingProcessParentFileName, InitiatingProcessFileName
| project ActionType, DeviceName, InitiatingProcessAccountName, InitiatingProcessParentFileName, InitiatingProcessFileName, visitedURLs, Connections=array_length(visitedURLs)
| where visitedURLs contains "oauth2.googleapis.com" and visitedURLs has_any ("sheets.googleapis.com","drive.googleapis.com") // may allow for higher fidelity as the GC2 go application communicates to both the google drive folder and sheets API.

Find files created by the process that created the suspicious connections

let excludedProcessFileNames = datatable (browser:string)["teams.exe","GoogleUpdate.exe","outlook.exe","msedge.exe","chrome.exe","iexplorer.exe","brave.exe","firefox.exe"]; //add more browsers or mail clients where needed for exclusion 
let processComWithGoogleAPI = DeviceNetworkEvents 
| where not(InitiatingProcessFileName has_any (excludedProcessFileNames))
| where RemoteUrl has_any ("oauth2.googleapis.com","sheets.googleapis.com","drive.googleapis.com","www.googleapis.com") and isnotempty(InitiatingProcessFileName)
| distinct InitiatingProcessFileName;
DeviceFileEvents
| where ActionType == "FileCreated" and InitiatingProcessFileName in~ (processComWithGoogleAPI)

Find Processes and commandlines launched by the suspicious process communicating with Google API's

let excludedProcessFileNames = datatable (browser:string)["teams.exe","GoogleUpdate.exe","outlook.exe","msedge.exe","chrome.exe","iexplorer.exe","brave.exe","firefox.exe"]; //add more browsers or mail clients where needed for exclusion 
let processComWithGoogleAPI = DeviceNetworkEvents 
| where not(InitiatingProcessFileName has_any (excludedProcessFileNames))
| where RemoteUrl has_any ("oauth2.googleapis.com","sheets.googleapis.com","drive.googleapis.com","www.googleapis.com") and isnotempty(InitiatingProcessFileName)
| distinct InitiatingProcessFileName;
DeviceProcessEvents
| where FileName in~ (processComWithGoogleAPI) or InitiatingProcessFileName in~ (processComWithGoogleAPI) or InitiatingProcessParentFileName in~ (processComWithGoogleAPI)