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ChromePassDumper

Specific and simple tool for educational purposes: demonstrating live dumping of Chrome passwords in Windows OSes or practising a simulated scenario of "two-step offline attack" for password database stealing.

This tool is basically a script that dumps passwords stored in Google Chrome default profile of the live user.

Chrome is not storing passwods in clear in its databases, it ciphers them through Data Protection API and then stores the resultant BLOBS into the "login data" SQLITE file inside the user profile.

This code retrieves the ciphered BLOBs from such database and then requests the decription of cyphered BLOB to the Local Security Authority through Windows Data Protection API (DPAPI), writing decrypted values to a clear text file afterwards.

Since DPAPI uses several ciphering layers, and the first of them is derived (400 rounds PBKDF2) from user password, access to DPAPI decryption functions is not possible if the user is not logged in the live Windows system, making the offline decryption of Chrome passwords a matter of slow, unfeasible bruteforcing. This approach presents an enhancement respect previous versions of Chrome, which stored passwords in clear, but it is still poses a compromisable vector in case the computer does not use full disk encryption. This is possible thanks to two-step offline DPAPI attacks (see below).

A sample auxiliary BAT script is provided for demonstration purposes as a launcher/dropper tool, which can circunvent the forementioned security provided by DPAPI using a "two-step offline attack" when target computer has not full disk encryption and the attacker has access to computer at least two times. The technique would be like this:

##STEP ONE

  1. "Compile" this script to EXE using PyInstaller tool inside a Python 2.7 valid installation (http://www.pyinstaller.org/).

  2. Access the target filesystem with a live linux system or any similar tool that enables you to read/write target filesystem.

  3. Copy the launcher BAT to profiles start menu "start" folder (%APPDATA%/Microsoft/Windows/Start menu/Programs/Startup), so it executes on next windows boot.

  4. Copy the compiled EXE to %APPDATA% folder directly.

  5. Unmount the filesystem cleanly and await for the user to log in at least one time.

    When user logs in, BAT file will launch, calling the EXE'd script, which will make the password dumping to clear text file process leveraging the fact that theuser is logged in and hence the DPAPI is accesible and ready for BLOB decryption. BAT file will erase itself so EXE file will never be executed a second time and startup environment will be clean again.

##STEP TWO

  1. Access the target filesystem with a live linux system or any similar tool that enables you to read/write target filesystem.
  2. Retrieve the password dump file: %APPDATA%/audit.log.
  3. Clean evidence (dump file and EXE file).

#DISCLAIMER

These materials are for educational and research purposes only. Do not attempt to violate the law with anything contained here. If this is your intention, neither the author or the organization presenting this material is going to accept responsibility for your actions.