Archive Collected Data: Archive via Custom Method

An adversary may compress or encrypt data that is collected prior to exfiltration using a custom method. Adversaries may choose to use custom archival methods, such as encryption with XOR or stream ciphers implemented with no external library or utility references. Custom implementations of well-known compression algorithms have also been used.[1]

ID: T1560.003
Sub-technique of:  T1560
Tactic: Collection
Platforms: Linux, Windows, macOS
Version: 1.0
Created: 20 February 2020
Last Modified: 25 March 2020

Procedure Examples

Name Description

ADVSTORESHELL compresses output data generated by command execution with a custom implementation of the Lempel–Ziv–Welch (LZW) algorithm.[1]


Agent.btz saves system information into an XML file that is then XOR-encoded.[5]


Attor encrypts collected data with a custom implementation of Blowfish and RSA ciphers.[16]


CopyKittens encrypts data with a substitute cipher prior to exfiltration.[22]


Modules can be pushed to and executed by Duqu that copy data to a staging area, compress it, and XOR encrypt it.[3]


TRINITY malware used by FIN6 encodes data gathered from the victim with a simple substitution cipher and single-byte XOR using the 0xAA key.[21]


FLASHFLOOD employs the same encoding scheme as SPACESHIP for data it stages. Data is compressed with zlib, and bytes are rotated four times before being XOR'ed with 0x23.[7]


HAWKBALL has encrypted data with XOR before sending it over the C2 channel.[13]


InvisiMole uses a variation of the XOR cipher to encrypt files before exfiltration.[2]


Kimsuky has used RC4 encryption before exfil.[23]

Lazarus Group

A Lazarus Group malware sample encrypts data using a simple byte based XOR operation prior to exfiltration.[24][25][26][27]


Machete's collected data is encrypted with AES before exfiltration.[14]


MESSAGETAP has XOR-encrypted and stored contents of SMS messages that matched its target list. [18]


Okrum has used a custom implementation of AES encryption to encrypt collected data.[17]


OopsIE compresses collected files with a simple character replacement scheme before sending them to its C2 server.[15]


OwaAuth DES-encrypts captured credentials using the key 12345678 before writing the credentials to a log file.[4]


Ramsay can store collected documents in a custom container after encrypting and compressing them using RC4 and WinRAR.[20]


RawPOS encodes credit card data it collected from the victim with XOR.[10][11][12]


Reaver encrypts collected data with an incremental XOR key prior to exfiltration.[9]


RGDoor encrypts files with XOR before sending them back to the C2 server.[6]

Rising Sun

Rising Sun can archive data using RC4 encryption and Base64 encoding prior to exfiltration.[19]


Data SPACESHIP copies to the staging area is compressed with zlib. Bytes are rotated by four positions and XOR'ed with 0x23.[7]


T9000 encrypts collected data using a single byte XOR key.[8]


This type of attack technique cannot be easily mitigated with preventive controls since it is based on the abuse of system features.


Custom archival methods can be very difficult to detect, since many of them use standard programming language concepts, such as bitwise operations.


  1. ESET. (2016, October). En Route with Sednit - Part 2: Observing the Comings and Goings. Retrieved November 21, 2016.
  2. Hromcová, Z. (2018, June 07). InvisiMole: Surprisingly equipped spyware, undercover since 2013. Retrieved July 10, 2018.
  3. Symantec Security Response. (2011, November). W32.Duqu: The precursor to the next Stuxnet. Retrieved September 17, 2015.
  4. Dell SecureWorks Counter Threat Unit Threat Intelligence. (2015, August 5). Threat Group-3390 Targets Organizations for Cyberespionage. Retrieved August 18, 2018.
  5. Shevchenko, S.. (2008, November 30). Agent.btz - A Threat That Hit Pentagon. Retrieved April 8, 2016.
  6. Falcone, R. (2018, January 25). OilRig uses RGDoor IIS Backdoor on Targets in the Middle East. Retrieved July 6, 2018.
  7. FireEye Labs. (2015, April). APT30 AND THE MECHANICS OF A LONG-RUNNING CYBER ESPIONAGE OPERATION. Retrieved May 1, 2015.
  8. Grunzweig, J. and Miller-Osborn, J.. (2016, February 4). T9000: Advanced Modular Backdoor Uses Complex Anti-Analysis Techniques. Retrieved April 15, 2016.
  9. Grunzweig, J. and Miller-Osborn, J. (2017, November 10). New Malware with Ties to SunOrcal Discovered. Retrieved November 16, 2017.
  10. TrendLabs Security Intelligence Blog. (2015, April). RawPOS Technical Brief. Retrieved October 4, 2017.
  11. Bromiley, M. and Lewis, P. (2016, October 7). Attacking the Hospitality and Gaming Industries: Tracking an Attacker Around the World in 7 Years. Retrieved October 6, 2017.
  12. Visa. (2015, March). Visa Security Alert: "RawPOS" Malware Targeting Lodging Merchants. Retrieved October 6, 2017.
  13. Patil, S. and Williams, M.. (2019, June 5). Government Sector in Central Asia Targeted With New HAWKBALL Backdoor Delivered via Microsoft Office Vulnerabilities. Retrieved June 20, 2019.
  14. ESET. (2019, July). MACHETE JUST GOT SHARPER Venezuelan government institutions under attack. Retrieved September 13, 2019.
  1. Lee, B., Falcone, R. (2018, February 23). OopsIE! OilRig Uses ThreeDollars to Deliver New Trojan. Retrieved July 16, 2018.
  3. Hromcova, Z. (2019, July). OKRUM AND KETRICAN: AN OVERVIEW OF RECENT KE3CHANG GROUP ACTIVITY. Retrieved May 6, 2020.
  4. Leong, R., Perez, D., Dean, T. (2019, October 31). MESSAGETAP: Who’s Reading Your Text Messages?. Retrieved May 11, 2020.
  5. Sherstobitoff, R., Malhotra, A., et. al.. (2018, December 18). Operation Sharpshooter Campaign Targets Global Defense, Critical Infrastructure. Retrieved May 14, 2020.
  6. Sanmillan, I.. (2020, May 13). Ramsay: A cyber‑espionage toolkit tailored for air‑gapped networks. Retrieved May 27, 2020.
  7. FireEye Threat Intelligence. (2016, April). Follow the Money: Dissecting the Operations of the Cyber Crime Group FIN6. Retrieved June 1, 2016.
  8. Minerva Labs LTD and ClearSky Cyber Security. (2015, November 23). CopyKittens Attack Group. Retrieved September 11, 2017.
  9. Tarakanov , D.. (2013, September 11). The “Kimsuky” Operation: A North Korean APT?. Retrieved August 13, 2019.
  10. Novetta Threat Research Group. (2016, February 24). Operation Blockbuster: Unraveling the Long Thread of the Sony Attack. Retrieved February 25, 2016.
  11. Novetta Threat Research Group. (2016, February 24). Operation Blockbuster: Loaders, Installers and Uninstallers Report. Retrieved March 2, 2016.
  12. Novetta Threat Research Group. (2016, February 24). Operation Blockbuster: Remote Administration Tools & Content Staging Malware Report. Retrieved March 16, 2016.
  13. Sherstobitoff, R. (2018, February 12). Lazarus Resurfaces, Targets Global Banks and Bitcoin Users. Retrieved February 19, 2018.