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
Requires Network:  Yes
Contributors: William Cain
Version: 1.1
Created: 15 March 2020
Last Modified: 15 October 2021
Provided by LAYER 8

Procedure Examples

ID Name Description
S0331 Agent Tesla

Agent Tesla has routines for exfiltration over SMTP, FTP, and HTTP.[1][2][3]

G0050 APT32

APT32's backdoor can exfiltrate data by encoding it in the subdomain field of DNS packets.[4]

G0064 APT33

APT33 has used FTP to exfiltrate files (separately from the C2 channel).[5]

S0190 BITSAdmin

BITSAdmin can be used to create BITS Jobs to upload files from a compromised host.[6]

S0252 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.[7]

S0335 Carbon

Carbon uses HTTP to send data to the C2 server.[8]

S0107 Cherry Picker

Cherry Picker exfiltrates files over FTP.[9]

S0492 CookieMiner

CookieMiner has used the curl --upload-file command to exfiltrate data over HTTP.[10]


CORALDECK has exfiltrated data in HTTP POST headers.[11]

S0050 CosmicDuke

CosmicDuke exfiltrates collected files over FTP or WebDAV. Exfiltration servers can be separately configured from C2 servers.[12]

S0281 Dok

Dok exfiltrates logs of its execution stored in the /tmp folder over FTP using the curl command.[13]

G0037 FIN6

FIN6 has sent stolen payment card data to remote servers via HTTP POSTs.[14]

G0061 FIN8

FIN8 has used FTP to exfiltrate collected data.[15]

S0095 FTP

FTP may be used to exfiltrate data separate from the main command and control protocol.[16]

S0487 Kessel

Kessel can exfiltrate credentials and other information via HTTP POST request, TCP, and DNS.[17]


KONNI has used FTP to exfiltrate reconnaissance data out.[18]

G0032 Lazarus Group

Lazarus Group malware SierraBravo-Two generates an email message via SMTP containing information about newly infected victims.[19][20]

G0049 OilRig

OilRig has exfiltrated data over FTP separately from its primary C2 channel over DNS.[21]

S0428 PoetRAT

PoetRAT has used FTP for exfiltration.[22]

S0125 Remsec

Remsec can exfiltrate data via a DNS tunnel or email, separately from its C2 channel.[23]

G0076 Thrip

Thrip has used WinSCP to exfiltrate data from a targeted organization over FTP.[24]

S0466 WindTail

WindTail has the ability to automatically exfiltrate files using the macOS built-in utility /usr/bin/curl.[25]

G0102 Wizard Spider

Wizard Spider has exfiltrated victim information using FTP.[26][27]


ID Mitigation Description
M1057 Data Loss Prevention

Data loss prevention can detect and block sensitive data being sent over unencrypted protocols.

M1037 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.

M1031 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.

M1030 Network Segmentation

Follow best practices for network firewall configurations to allow only necessary ports and traffic to enter and exit the network.[28]


ID Data Source Data Component
DS0017 Command Command Execution
DS0022 File File Access
DS0029 Network Traffic Network Connection Creation
Network Traffic Content
Network Traffic Flow

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. [29]


  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. Walter, J. (2020, August 10). Agent Tesla | Old RAT Uses New Tricks to Stay on Top. Retrieved December 11, 2020.
  4. Dumont, R. (2019, March 20). Fake or Fake: Keeping up with OceanLotus decoys. Retrieved April 1, 2019.
  5. 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.
  6. Microsoft. (n.d.). BITSAdmin Tool. Retrieved January 12, 2018.
  7. Sherstobitoff, R., Saavedra-Morales, J. (2018, February 02). Gold Dragon Widens Olympics Malware Attacks, Gains Permanent Presence on Victims’ Systems. Retrieved June 6, 2018.
  8. ESET. (2017, March 30). Carbon Paper: Peering into Turla’s second stage backdoor. Retrieved November 7, 2018.
  9. Merritt, E.. (2015, November 16). Shining the Spotlight on Cherry Picker PoS Malware. Retrieved April 20, 2016.
  10. Chen, y., et al. (2019, January 31). Mac Malware Steals Cryptocurrency Exchanges’ Cookies. Retrieved July 22, 2020.
  11. FireEye. (2018, February 20). APT37 (Reaper): The Overlooked North Korean Actor. Retrieved March 1, 2018.
  12. F-Secure Labs. (2014, July). COSMICDUKE Cosmu with a twist of MiniDuke. Retrieved July 3, 2014.
  13. fluffybunny. (2019, July 9). OSX.Dok Analysis. Retrieved October 4, 2021.
  14. Chen, J. (2019, October 10). Magecart Card Skimmers Injected Into Online Shops. Retrieved September 9, 2020.
  15. 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. The DFIR Report. (2020, October 8). Ryuk’s Return. Retrieved October 9, 2020.
  12. The DFIR Report. (2020, November 5). Ryuk Speed Run, 2 Hours to Ransom. Retrieved November 6, 2020.
  13. Microsoft. (2004, February 6). Perimeter Firewall Design. Retrieved April 25, 2016.
  14. Gardiner, J., Cova, M., Nagaraja, S. (2014, February). Command & Control Understanding, Denying and Detecting. Retrieved April 20, 2016.