Archive Collected Data

An adversary may compress and/or encrypt data that is collected prior to exfiltration. Compressing the data can help to obfuscate the collected data and minimize the amount of data sent over the network. Encryption can be used to hide information that is being exfiltrated from detection or make exfiltration less conspicuous upon inspection by a defender.

Both compression and encryption are done prior to exfiltration, and can be performed using a utility, 3rd party library, or custom method.

ID: T1560
Sub-techniques:  T1560.001, T1560.002, T1560.003
Tactic: Collection
Platforms: Linux, Windows, macOS
Data Sources: Binary file metadata, File monitoring, Process command-line parameters, Process monitoring
Version: 1.0
Created: 20 February 2020
Last Modified: 21 October 2020

Procedure Examples

Name Description
ADVSTORESHELL

ADVSTORESHELL encrypts with the 3DES algorithm and a hardcoded key prior to exfiltration.[1]

Agent Tesla

Agent Tesla can encrypt data with 3DES before sending it over to a C2 server.[2]

APT28

APT28 used a publicly available tool to gather and compress multiple documents on the DCCC and DNC networks.[3]

APT32

APT32's backdoor has used LZMA compression and RC4 encryption before exfiltration.[4]

Aria-body

Aria-body has used ZIP to compress data gathered on a compromised host.[5]

Backdoor.Oldrea

Backdoor.Oldrea writes collected data to a temporary file in an encrypted form before exfiltration to a C2 server.[6]

BloodHound

BloodHound can compress data collected by its SharpHound ingestor into a ZIP file to be written to disk.[7]

Cadelspy

Cadelspy has the ability to compress stolen data into a .cab file.[8]

Daserf

Daserf hides collected data in password-protected .rar archives.[9]

Dragonfly 2.0

Dragonfly 2.0 compressed data into .zip files prior to exfiltrating it.[10]

Emotet

Emotet has been observed encrypting the data it collects before sending it to the C2 server. [11]

Empire

Empire can ZIP directories on the target system.[12]

Epic

Epic encrypts collected data using a public key framework before sending it over the C2 channel.[13] Some variants encrypt the collected data with AES and encode it with base64 before transmitting it to the C2 server.[14]

Exaramel for Windows

Exaramel for Windows automatically encrypts files before sending them to the C2 server.[15]

FELIXROOT

FELIXROOT encrypts collected data with AES and Base64 and then sends it to the C2 server.[16]

FIN6

Following data collection, FIN6 has compressed log files into a ZIP archive prior to staging and exfiltration.[17]

Gold Dragon

Gold Dragon encrypts data using Base64 before being sent to the command and control server.[18]

Honeybee

Honeybee adds collected files to a temp.zip file saved in the %temp% folder, then base64 encodes it and uploads it to control server.[19]

Ke3chang

The Ke3chang group has been known to compress data before exfiltration.[20]

Kessel

Kessel can RC4-encrypt credentials before sending to the C2.[21]

Lazarus Group

Lazarus Group malware RomeoDelta archives specified directories in .zip format, encrypts the .zip file, and uploads it to its C2 server. [22][23][24]

LightNeuron

LightNeuron contains a function to encrypt and store emails that it collects.[25]

Lurid

Lurid can compress data before sending it.[26]

Machete

Machete stores zipped files with profile data from installed web browsers.[27]

menuPass

menuPass has encrypted files and information before exfiltration.[28]

OSX_OCEANLOTUS.D

OSX_OCEANLOTUS.D scrambles and encrypts data using AES256 before sending it to the C2 server.[29]

Patchwork

Patchwork encrypted the collected files' path with AES and then encoded them with base64.[30]

Pillowmint

Pillowmint has encrypted stolen credit card information with AES and further encoded it with Base64.[31]

Prikormka

After collecting documents from removable media, Prikormka compresses the collected files, and encrypts it with Blowfish.[32]

Proton

Proton zips up files before exfiltrating them.[33]

Remexi

Remexi encrypts and adds all gathered browser data into files for upload to C2.[34]

RunningRAT

RunningRAT contains code to compress files.[18]

ShimRatReporter

ShimRatReporter used LZ compression to compress initial reconnaissance reports before sending to the C2.[35]

VERMIN

VERMIN encrypts the collected files using 3-DES.[36]

WellMail

WellMail can archive files on the compromised host.[37]

Zebrocy

Zebrocy uses an encryption method similar to RC4 as well as AES to encrypt data before exfiltration. [38][39]

Mitigations

Mitigation Description
Audit

System scans can be performed to identify unauthorized archival utilities.

Detection

Archival software and archived files can be detected in many ways. Common utilities that may be present on the system or brought in by an adversary may be detectable through process monitoring and monitoring for command-line arguments for known archival utilities. This may yield a significant number of benign events, depending on how systems in the environment are typically used.

A process that loads the Windows DLL crypt32.dll may be used to perform encryption, decryption, or verification of file signatures.

Consider detecting writing of files with extensions and/or headers associated with compressed or encrypted file types. Detection efforts may focus on follow-on exfiltration activity, where compressed or encrypted files can be detected in transit with a network intrusion detection or data loss prevention system analyzing file headers.[40]

References

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  15. Cherepanov, A., Lipovsky, R. (2018, October 11). New TeleBots backdoor: First evidence linking Industroyer to NotPetya. Retrieved November 27, 2018.
  16. Patil, S. (2018, June 26). Microsoft Office Vulnerabilities Used to Distribute FELIXROOT Backdoor in Recent Campaign. Retrieved July 31, 2018.
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  1. Dumont, R., M.Léveillé, M., Porcher, H. (2018, December 1). THE DARK SIDE OF THE FORSSHE A landscape of OpenSSH backdoors. Retrieved July 16, 2020.
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  4. Sherstobitoff, R. (2018, February 12). Lazarus Resurfaces, Targets Global Banks and Bitcoin Users. Retrieved February 19, 2018.
  5. Faou, M. (2019, May). Turla LightNeuron: One email away from remote code execution. Retrieved June 24, 2019.
  6. Villeneuve, N., Sancho, D. (2011). THE “LURID” DOWNLOADER. Retrieved November 12, 2014.
  7. ESET. (2019, July). MACHETE JUST GOT SHARPER Venezuelan government institutions under attack. Retrieved September 13, 2019.
  8. United States District Court Southern District of New York (USDC SDNY) . (2018, December 17). United States of America v. Zhu Hua and Zhang Shilong. Retrieved April 17, 2019.
  9. Horejsi, J. (2018, April 04). New MacOS Backdoor Linked to OceanLotus Found. Retrieved November 13, 2018.
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  13. Patrick Wardle. (n.d.). Mac Malware of 2017. Retrieved September 21, 2018.
  14. Legezo, D. (2019, January 30). Chafer used Remexi malware to spy on Iran-based foreign diplomatic entities. Retrieved April 17, 2019.
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  19. ESET. (2018, November 20). Sednit: What’s going on with Zebrocy?. Retrieved February 12, 2019.
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