Exfiltration Over Alternative Protocol: Exfiltration Over Unencrypted/Obfuscated Non-C2 Protocol

Adversaries may steal data by exfiltrating it over an un-encrypted network protocol other than that of the existing command and control channel. The data may also be sent to an alternate network location from the main command and control server.

Adversaries may opt to obfuscate this data, without the use of encryption, within network protocols that are natively unencrypted (such as HTTP, FTP, or DNS). This may include custom or publicly available encoding/compression algorithms (such as base64) as well as embedding data within protocol headers and fields.

ID: T1048.003
Sub-technique of:  T1048
Tactic: Exfiltration
Platforms: Linux, Windows, macOS
Data Sources: Netflow/Enclave netflow, Network protocol analysis, Packet capture, Process use of network
Requires Network:  Yes
Version: 1.0
Created: 15 March 2020
Last Modified: 28 March 2020

Procedure Examples

Name Description
Agent Tesla

Agent Tesla has routines for exfiltration over SMTP, FTP, and HTTP.[1][2]

APT32

APT32's backdoor can exfiltrate data by encoding it in the subdomain field of DNS packets.[3]

APT33

APT33 has used FTP to exfiltrate files (separately from the C2 channel).[4]

BITSAdmin

BITSAdmin can be used to create BITS Jobs to upload files from a compromised host.[5]

Brave Prince

Some Brave Prince variants have used South Korea's Daum email service to exfiltrate information, and later variants have posted the data to a web server via an HTTP post command.[6]

Carbon

Carbon uses HTTP to send data to the C2 server.[7]

Cherry Picker

Cherry Picker exfiltrates files over FTP.[8]

CookieMiner

CookieMiner has used the curl --upload-file command to exfiltrate data over HTTP.[9]

CORALDECK

CORALDECK has exfiltrated data in HTTP POST headers.[10]

CosmicDuke

CosmicDuke exfiltrates collected files over FTP or WebDAV. Exfiltration servers can be separately configured from C2 servers.[11]

FIN6

FIN6 has sent stolen payment card data to remote servers via HTTP POSTs.[12]

FIN8

FIN8 has used FTP to exfiltrate collected data.[13]

FTP

FTP may be used to exfiltrate data separate from the main command and control protocol.[14]

Kessel

Kessel can exfiltrate credentials and other information via HTTP POST request, TCP, and DNS.[15]

KONNI

KONNI has used FTP to exfiltrate reconnaissance data out.[16]

Lazarus Group

Lazarus Group malware SierraBravo-Two generates an email message via SMTP containing information about newly infected victims.[17][18]

OilRig

OilRig has exfiltrated data over FTP separately from its primary C2 channel over DNS.[19]

PoetRAT

PoetRAT has used FTP for exfiltration.[20]

Remsec

Remsec can exfiltrate data via a DNS tunnel or email, separately from its C2 channel.[21]

Thrip

Thrip has used WinSCP to exfiltrate data from a targeted organization over FTP.[22]

WindTail

WindTail has the ability to automatically exfiltrate files using the macOS built-in utility /usr/bin/curl.[23]

Mitigations

Mitigation Description
Filter Network Traffic

Enforce proxies and use dedicated servers for services such as DNS and only allow those systems to communicate over respective ports/protocols, instead of all systems within a network.

Network Intrusion Prevention

Network intrusion detection and prevention systems that use network signatures to identify traffic for specific adversary command and control infrastructure and malware can be used to mitigate activity at the network level.

Network Segmentation

Follow best practices for network firewall configurations to allow only necessary ports and traffic to enter and exit the network.[24]

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. [25]

References

  1. Brumaghin, E., et al. (2018, October 15). Old dog, new tricks - Analysing new RTF-based campaign distributing Agent Tesla, Loki with PyREbox. Retrieved November 5, 2018.
  2. Arsene, L. (2020, April 21). Oil & Gas Spearphishing Campaigns Drop Agent Tesla Spyware in Advance of Historic OPEC+ Deal. Retrieved May 19, 2020.
  3. Dumont, R. (2019, March 20). Fake or Fake: Keeping up with OceanLotus decoys. Retrieved April 1, 2019.
  4. Security Response attack Investigation Team. (2019, March 27). Elfin: Relentless Espionage Group Targets Multiple Organizations in Saudi Arabia and U.S.. Retrieved April 10, 2019.
  5. Microsoft. (n.d.). BITSAdmin Tool. Retrieved January 12, 2018.
  6. Sherstobitoff, R., Saavedra-Morales, J. (2018, February 02). Gold Dragon Widens Olympics Malware Attacks, Gains Permanent Presence on Victims’ Systems. Retrieved June 6, 2018.
  7. ESET. (2017, March 30). Carbon Paper: Peering into Turla’s second stage backdoor. Retrieved November 7, 2018.
  8. Merritt, E.. (2015, November 16). Shining the Spotlight on Cherry Picker PoS Malware. Retrieved April 20, 2016.
  9. Chen, y., et al. (2019, January 31). Mac Malware Steals Cryptocurrency Exchanges’ Cookies. Retrieved July 22, 2020.
  10. FireEye. (2018, February 20). APT37 (Reaper): The Overlooked North Korean Actor. Retrieved March 1, 2018.
  11. F-Secure Labs. (2014, July). COSMICDUKE Cosmu with a twist of MiniDuke. Retrieved July 3, 2014.
  12. Chen, J. (2019, October 10). Magecart Card Skimmers Injected Into Online Shops. Retrieved September 9, 2020.
  13. Elovitz, S. & Ahl, I. (2016, August 18). Know Your Enemy: New Financially-Motivated & Spear-Phishing Group. Retrieved February 26, 2018.
  1. Wikipedia. (2016, June 15). File Transfer Protocol. Retrieved July 20, 2016.
  2. 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.
  3. Karmi, D. (2020, January 4). A Look Into Konni 2019 Campaign. Retrieved April 28, 2020.
  4. Novetta Threat Research Group. (2016, February 24). Operation Blockbuster: Unraveling the Long Thread of the Sony Attack. Retrieved February 25, 2016.
  5. Novetta Threat Research Group. (2016, February 24). Operation Blockbuster: Remote Administration Tools & Content Staging Malware Report. Retrieved March 16, 2016.
  6. Grunzweig, J. and Falcone, R.. (2016, October 4). OilRig Malware Campaign Updates Toolset and Expands Targets. Retrieved May 3, 2017.
  7. Mercer, W, et al. (2020, April 16). PoetRAT: Python RAT uses COVID-19 lures to target Azerbaijan public and private sectors. Retrieved April 27, 2020.
  8. Kaspersky Lab's Global Research & Analysis Team. (2016, August 9). The ProjectSauron APT. Retrieved August 17, 2016.
  9. Security Response Attack Investigation Team. (2018, June 19). Thrip: Espionage Group Hits Satellite, Telecoms, and Defense Companies. Retrieved July 10, 2018.
  10. Wardle, Patrick. (2019, January 15). Middle East Cyber-Espionage analyzing WindShift's implant: OSX.WindTail (part 2). Retrieved October 3, 2019.
  11. Microsoft. (2004, February 6). Perimeter Firewall Design. Retrieved April 25, 2016.
  12. Gardiner, J., Cova, M., Nagaraja, S. (2014, February). Command & Control Understanding, Denying and Detecting. Retrieved April 20, 2016.