Data Encoding: Standard Encoding

ID Name
T1132.001 Standard Encoding
T1132.002 Non-Standard Encoding

Adversaries may encode data with a standard data encoding system to make the content of command and control traffic more difficult to detect. Command and control (C2) information can be encoded using a standard data encoding system that adheres to existing protocol specifications. Common data encoding schemes include ASCII, Unicode, hexadecimal, Base64, and MIME.[1] [2] Some data encoding systems may also result in data compression, such as gzip.

ID: T1132.001
Sub-technique of:  T1132
Tactic: Command And Control
Platforms: Linux, Windows, macOS
Permissions Required: User
Data Sources: Network protocol analysis, Packet capture, Process monitoring, Process use of network
Version: 1.0
Created: 14 March 2020
Last Modified: 14 March 2020

Procedure Examples

Name Description
ADVSTORESHELL

C2 traffic from ADVSTORESHELL is encrypted, then encoded with Base64 encoding.[17]

APT19

An APT19 HTTP malware variant used Base64 to encode communications to the C2 server.[51]

APT33

APT33 has used base64 to encode command and control traffic.[54]

Astaroth

Astaroth encodes data using Base64 before sending it to the C2 server. [30]

AutoIt backdoor

AutoIt backdoor has sent a C2 response that was base64-encoded.[18]

BabyShark

BabyShark has encoded data using certutil before exfiltration.[39]

Backdoor.Oldrea

Some Backdoor.Oldrea samples use standard Base64 + bzip2, and some use standard Base64 + reverse XOR + RSA-2048 to decrypt data received from C2 servers.[4]

BADNEWS

BADNEWS encodes C2 traffic with base64.[18][22][23]

BRONZE BUTLER

Several BRONZE BUTLER tools encode data with base64 when posting it to a C2 server.[28]

BS2005

BS2005 uses Base64 encoding for communication in the message body of an HTTP request.[5]

Carbanak

Carbanak encodes the message body of HTTP traffic with Base64.[40][41]

ChChes

ChChes can encode C2 data with a custom technique that utilizes Base64.[42][43]

Cobian RAT

Cobian RAT obfuscates communications with the C2 server using Base64 encoding.[21]

CORESHELL

CORESHELL C2 messages are Base64-encoded.[24]

Daserf

Daserf uses custom base64 encoding to obfuscate HTTP traffic.[28]

Denis

Denis encodes the data sent to the server in Base64.[29]

Dipsind

Dipsind encodes C2 traffic with base64.[10]

down_new

down_new has the ability to base64 encode C2 communications.[50]

Ebury

Ebury has encoded C2 traffic in hexadecimal format.[33]

Elise

Elise exfiltrates data using cookie values that are Base64-encoded.[3]

Felismus

Some Felismus samples use a custom method for C2 traffic that utilizes Base64.[44]

Fysbis

Fysbis can use Base64 to encode its C2 traffic.[37]

Helminth

For C2 over HTTP, Helminth encodes data with base64 and sends it via the "Cookie" field of HTTP requests. For C2 over DNS, Helminth converts ASCII characters into their hexadecimal values and sends the data in cleartext.[26]

HOPLIGHT

HOPLIGHT has utilized Zlib compression to obfuscate the communications payload. [32]

Ixeshe

Ixeshe uses custom Base64 encoding schemes to obfuscate command and control traffic in the message body of HTTP requests.[12][13]

JHUHUGIT

A JHUHUGIT variant encodes C2 POST data base64.[19]

Kazuar

Kazuar encodes communications to the C2 server in Base64.[16]

KONNI

KONNI has used a custom base64 key to encode stolen data before exfiltration.[45]

Lazarus Group

A Lazarus Group malware sample encodes data with base64.[52]

MechaFlounder

MechaFlounder has the ability to use base16 encoded strings in C2.[49]

Mis-Type

Mis-Type uses Base64 encoding for C2 traffic.[7]

Misdat

Misdat network traffic is Base64-encoded plaintext.[7]

More_eggs

More_eggs has used basE91 encoding, along with encryption, for C2 communication.[38]

MuddyWater

MuddyWater has base64 encoded C2 communications.[55]

njRAT

njRAT uses Base64 encoding for C2 traffic.[35]

Octopus

Octopus encodes C2 communications in Base64.[20]

Okrum

Okrum has used base64 to encode C2 communication.[46]

OopsIE

OopsIE encodes data in hexadecimal format over the C2 channel.[11]

Patchwork

Patchwork used Base64 to encode C2 traffic.[53]

Pisloader

Responses from the Pisloader C2 server are base32-encoded.[8]

PowerShower

PowerShower has the ability to encode C2 communications with base64 encoding.[47][48]

POWERSTATS

POWERSTATS encoded C2 traffic with base64.[27]

POWRUNER

POWRUNER can use base64 encoded C2 communications.[25]

Prikormka

Prikormka encodes C2 traffic with Base64.[9]

QUADAGENT

QUADAGENT encodes C2 communications with base64.[14]

Revenge RAT

Revenge RAT uses Base64 to encode information sent to the C2 server.[34]

RogueRobin

RogueRobin base64 encodes strings that are sent to the C2 over its DNS tunnel.[6]

S-Type

S-Type uses Base64 encoding for C2 traffic.[7]

Sandworm Team

Sandworm Team's BCS-server tool uses base64 encoding and HTML tags for the communication traffic between the C2 server.[57]

SeaDuke

SeaDuke C2 traffic is base64-encoded.[15]

SpeakUp

SpeakUp encodes C&C communication using Base64. [31]

Tropic Trooper

Tropic Trooper has used base64 encoding to hide command strings delivered from the C2.[56]

Zebrocy

Zebrocy has used URL/Percent Encoding on data exfiltrated via HTTP POST requests.[36]

Mitigations

Mitigation Description
Network Intrusion Prevention

Network intrusion detection and prevention systems that use network signatures to identify traffic for specific adversary malware can be used to mitigate activity at the network level. Signatures are often for unique indicators within protocols and may be based on the specific obfuscation technique used by a particular adversary or tool, and will likely be different across various malware families and versions. Adversaries will likely change tool C2 signatures over time or construct protocols in such a way as to avoid detection by common defensive tools.

Detection

Analyze network data for uncommon data flows (e.g., a client sending significantly more data than it receives from a server). Processes utilizing the network that do not normally have network communication or have never been seen before are suspicious. Analyze packet contents to detect communications that do not follow the expected protocol behavior for the port that is being used.[58]

References

  1. Wikipedia. (2016, December 26). Binary-to-text encoding. Retrieved March 1, 2017.
  2. Wikipedia. (2017, February 19). Character Encoding. Retrieved March 1, 2017.
  3. Falcone, R., et al.. (2015, June 16). Operation Lotus Blossom. Retrieved February 15, 2016.
  4. Symantec Security Response. (2014, July 7). Dragonfly: Cyberespionage Attacks Against Energy Suppliers. Retrieved April 8, 2016.
  5. Villeneuve, N., Bennett, J. T., Moran, N., Haq, T., Scott, M., & Geers, K. (2014). OPERATION “KE3CHANG”: Targeted Attacks Against Ministries of Foreign Affairs. Retrieved November 12, 2014.
  6. Falcone, R., et al. (2018, July 27). New Threat Actor Group DarkHydrus Targets Middle East Government. Retrieved August 2, 2018.
  7. Gross, J. (2016, February 23). Operation Dust Storm. Retrieved September 19, 2017.
  8. Grunzweig, J., et al. (2016, May 24). New Wekby Attacks Use DNS Requests As Command and Control Mechanism. Retrieved August 17, 2016.
  9. Cherepanov, A.. (2016, May 17). Operation Groundbait: Analysis of a surveillance toolkit. Retrieved May 18, 2016.
  10. Windows Defender Advanced Threat Hunting Team. (2016, April 29). PLATINUM: Targeted attacks in South and Southeast Asia. Retrieved February 15, 2018.
  11. Lee, B., Falcone, R. (2018, February 23). OopsIE! OilRig Uses ThreeDollars to Deliver New Trojan. Retrieved July 16, 2018.
  12. Moran, N., & Villeneuve, N. (2013, August 12). Survival of the Fittest: New York Times Attackers Evolve Quickly [Blog]. Retrieved November 12, 2014.
  13. Sancho, D., et al. (2012, May 22). IXESHE An APT Campaign. Retrieved June 7, 2019.
  14. Lee, B., Falcone, R. (2018, July 25). OilRig Targets Technology Service Provider and Government Agency with QUADAGENT. Retrieved August 9, 2018.
  15. Grunzweig, J.. (2015, July 14). Unit 42 Technical Analysis: Seaduke. Retrieved August 3, 2016.
  16. Levene, B, et al. (2017, May 03). Kazuar: Multiplatform Espionage Backdoor with API Access. Retrieved July 17, 2018.
  17. Kaspersky Lab's Global Research and Analysis Team. (2015, December 4). Sofacy APT hits high profile targets with updated toolset. Retrieved December 10, 2015.
  18. Settle, A., et al. (2016, August 8). MONSOON - Analysis Of An APT Campaign. Retrieved September 22, 2016.
  19. Unit 42. (2017, December 15). Unit 42 Playbook Viewer. Retrieved December 20, 2017.
  20. Kaspersky Lab's Global Research & Analysis Team. (2018, October 15). Octopus-infested seas of Central Asia. Retrieved November 14, 2018.
  21. Yadav, A., et al. (2017, August 31). Cobian RAT – A backdoored RAT. Retrieved November 13, 2018.
  22. Levene, B. et al.. (2018, March 7). Patchwork Continues to Deliver BADNEWS to the Indian Subcontinent. Retrieved March 31, 2018.
  23. Lunghi, D., et al. (2017, December). Untangling the Patchwork Cyberespionage Group. Retrieved July 10, 2018.
  24. FireEye. (2015). APT28: A WINDOW INTO RUSSIA’S CYBER ESPIONAGE OPERATIONS?. Retrieved August 19, 2015.
  25. Sardiwal, M, et al. (2017, December 7). New Targeted Attack in the Middle East by APT34, a Suspected Iranian Threat Group, Using CVE-2017-11882 Exploit. Retrieved December 20, 2017.
  26. Falcone, R. and Lee, B.. (2016, May 26). The OilRig Campaign: Attacks on Saudi Arabian Organizations Deliver Helminth Backdoor. Retrieved May 3, 2017.
  27. Lancaster, T.. (2017, November 14). Muddying the Water: Targeted Attacks in the Middle East. Retrieved March 15, 2018.
  28. Counter Threat Unit Research Team. (2017, October 12). BRONZE BUTLER Targets Japanese Enterprises. Retrieved January 4, 2018.
  29. Dahan, A. (2017). Operation Cobalt Kitty. Retrieved December 27, 2018.
  1. Doaty, J., Garrett, P.. (2018, September 10). We’re Seeing a Resurgence of the Demonic Astaroth WMIC Trojan. Retrieved April 17, 2019.
  2. Check Point Research. (2019, February 4). SpeakUp: A New Undetected Backdoor Linux Trojan. Retrieved April 17, 2019.
  3. US-CERT. (2019, April 10). MAR-10135536-8 – North Korean Trojan: HOPLIGHT. Retrieved April 19, 2019.
  4. M.Léveillé, M.. (2014, February 21). An In-depth Analysis of Linux/Ebury. Retrieved April 19, 2019.
  5. Livelli, K, et al. (2018, November 12). Operation Shaheen. Retrieved May 1, 2019.
  6. Fidelis Cybersecurity. (2013, June 28). Fidelis Threat Advisory #1009: "njRAT" Uncovered. Retrieved June 4, 2019.
  7. Accenture Security. (2018, November 29). SNAKEMACKEREL. Retrieved April 15, 2019.
  8. Doctor Web. (2014, November 21). Linux.BackDoor.Fysbis.1. Retrieved December 7, 2017.
  9. Villadsen, O.. (2019, August 29). More_eggs, Anyone? Threat Actor ITG08 Strikes Again. Retrieved September 16, 2019.
  10. Unit 42. (2019, February 22). New BabyShark Malware Targets U.S. National Security Think Tanks. Retrieved October 7, 2019.
  11. Kaspersky Lab's Global Research and Analysis Team. (2015, February). CARBANAK APT THE GREAT BANK ROBBERY. Retrieved August 23, 2018.
  12. Bennett, J., Vengerik, B. (2017, June 12). Behind the CARBANAK Backdoor. Retrieved June 11, 2018.
  13. Miller-Osborn, J. and Grunzweig, J.. (2017, February 16). menuPass Returns with New Malware and New Attacks Against Japanese Academics and Organizations. Retrieved March 1, 2017.
  14. Nakamura, Y.. (2017, February 17). ChChes - Malware that Communicates with C&C Servers Using Cookie Headers. Retrieved March 1, 2017.
  15. Somerville, L. and Toro, A. (2017, March 30). Playing Cat & Mouse: Introducing the Felismus Malware. Retrieved November 16, 2017.
  16. Karmi, D. (2020, January 4). A Look Into Konni 2019 Campaign. Retrieved April 28, 2020.
  17. Hromcova, Z. (2019, July). OKRUM AND KETRICAN: AN OVERVIEW OF RECENT KE3CHANG GROUP ACTIVITY. Retrieved May 6, 2020.
  18. Lancaster, T. (2018, November 5). Inception Attackers Target Europe with Year-old Office Vulnerability. Retrieved May 8, 2020.
  19. GReAT. (2019, August 12). Recent Cloud Atlas activity. Retrieved May 8, 2020.
  20. Falcone, R. (2019, March 4). New Python-Based Payload MechaFlounder Used by Chafer. Retrieved May 27, 2020.
  21. Chen, J. et al. (2019, November). Operation ENDTRADE: TICK’s Multi-Stage Backdoors for Attacking Industries and Stealing Classified Data. Retrieved June 9, 2020.
  22. Grunzweig, J., Lee, B. (2016, January 22). New Attacks Linked to C0d0so0 Group. Retrieved August 2, 2018.
  23. Sherstobitoff, R. (2018, February 12). Lazarus Resurfaces, Targets Global Banks and Bitcoin Users. Retrieved February 19, 2018.
  24. Cymmetria. (2016). Unveiling Patchwork - The Copy-Paste APT. Retrieved August 3, 2016.
  25. Ackerman, G., et al. (2018, December 21). OVERRULED: Containing a Potentially Destructive Adversary. Retrieved January 17, 2019.
  26. ClearSky. (2019, June). Iranian APT group ‘MuddyWater’ Adds Exploits to Their Arsenal. Retrieved May 14, 2020.
  27. Chen, J.. (2020, May 12). Tropic Trooper’s Back: USBferry Attack Targets Air gapped Environments. Retrieved May 20, 2020.
  28. Cherepanov, A.. (2016, December 13). The rise of TeleBots: Analyzing disruptive KillDisk attacks. Retrieved June 10, 2020.
  29. Gardiner, J., Cova, M., Nagaraja, S. (2014, February). Command & Control Understanding, Denying and Detecting. Retrieved April 20, 2016.