Web Service: Bidirectional Communication

Adversaries may use an existing, legitimate external Web service as a means for sending commands to and receiving output from a compromised system over the Web service channel. Compromised systems may leverage popular websites and social media to host command and control (C2) instructions. Those infected systems can then send the output from those commands back over that Web service channel. The return traffic may occur in a variety of ways, depending on the Web service being utilized. For example, the return traffic may take the form of the compromised system posting a comment on a forum, issuing a pull request to development project, updating a document hosted on a Web service, or by sending a Tweet.

Popular websites and social media acting as a mechanism for C2 may give a significant amount of cover due to the likelihood that hosts within a network are already communicating with them prior to a compromise. Using common services, such as those offered by Google or Twitter, makes it easier for adversaries to hide in expected noise. Web service providers commonly use SSL/TLS encryption, giving adversaries an added level of protection.

ID: T1102.002
Sub-technique of:  T1102
Tactic: Command And Control
Platforms: Linux, Windows, macOS
Permissions Required: User
Data Sources: Host network interface, Netflow/Enclave netflow, Network protocol analysis, Packet capture, SSL/TLS inspection
Version: 1.0
Created: 14 March 2020
Last Modified: 26 March 2020

Procedure Examples

Name Description
APT12

APT12 has used blogs and WordPress for C2 infrastructure.[33]

APT37

APT37 leverages social networking sites and cloud platforms (AOL, Twitter, Yandex, Mediafire, pCloud, Dropbox, and Box) for C2.[7][31]

APT39

APT39 has communicated with C2 through files uploaded to DropBox.[34]

BADNEWS

BADNEWS can use multiple C2 channels, including RSS feeds, Github, forums, and blogs.[21][22][23]

BLACKCOFFEE

BLACKCOFFEE has also obfuscated its C2 traffic as normal traffic to sites such as Github.[24][25]

CALENDAR

The CALENDAR malware communicates through the use of events in Google Calendar.[5][15]

Carbanak

Carbanak has used a VBScript named "ggldr" that uses Google Apps Script, Sheets, and Forms services for C2.[29]

CloudDuke

One variant of CloudDuke uses a Microsoft OneDrive account to exchange commands and stolen data with its operators.[17]

Comnie

Comnie uses blogs and third-party sites (GitHub, tumbler, and BlogSpot) to avoid DNS-based blocking of their communication to the command and control server.[2]

ComRAT

ComRAT has the ability to use the Gmail web UI to receive commands and exfiltrate information.[26]

CozyCar

CozyCar uses Twitter as a backup C2 channel to Twitter accounts specified in its configuration file.[4]

DOGCALL

DOGCALL is capable of leveraging cloud storage APIs such as Cloud, Box, Dropbox, and Yandex for C2.[7][10]

Empire

Empire can use Dropbox and GitHub for C2.[1]

FIN7

FIN7 used legitimate services like Google Docs, Google Scripts, and Pastebin for C2.[30]

GLOOXMAIL

GLOOXMAIL communicates to servers operated by Google using the Jabber/XMPP protocol.[5][6]

KARAE

KARAE can use public cloud-based storage providers for command and control.[7]

Kazuar

Kazuar has used compromised WordPress blogs as C2 servers.[3]

LOWBALL

LOWBALL uses the Dropbox cloud storage service for command and control.[11]

Magic Hound

Magic Hound malware can use a SOAP Web service to communicate with its C2 server.[32]

Orz

Orz has used Technet and Pastebin web pages for command and control.[16]

POORAIM

POORAIM has used AOL Instant Messenger for C2.[7]

PowerStallion

PowerStallion uses Microsoft OneDrive as a C2 server via a network drive mapped with net use.[20]

Revenge RAT

Revenge RAT used blogpost.com as its primary command and control server during a campaign.[19]

RogueRobin

RogueRobin has used Google Drive as a Command and Control channel. [18]

ROKRAT

ROKRAT leverages legitimate social networking sites and cloud platforms (Twitter, Yandex, and Mediafire) for C2 communications.[8][9]

Sandworm Team

Sandworm Team has used the Telegram Bot API from Telegram Messenger to send and receive commands to its Python backdoor. Sandworm Team also used legitimate M.E.Doc software update check requests for sending and receiving commands and hosted malicious payloads on putdrive.com.[35][36]

SLOWDRIFT

SLOWDRIFT uses cloud based services for C2.[7]

Turla

A Turla JavaScript backdoor has used Google Apps Script as its C2 server.[27][28]

Twitoor

Twitoor uses Twitter for command and control.[12]

UBoatRAT

UBoatRAT has used GitHub and a public blog service in Hong Kong for C2 communications.[13]

yty

yty communicates to the C2 server by retrieving a Google Doc.[14]

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.

Restrict Web-Based Content

Web proxies can be used to enforce external network communication policy that prevents use of unauthorized external services.

Detection

Host data that can relate unknown or suspicious process activity using a network connection is important to supplement any existing indicators of compromise based on malware command and control signatures and infrastructure or the presence of strong encryption. Packet capture analysis will require SSL/TLS inspection if data is encrypted. Analyze network data for uncommon data flows (e.g., a client sending significantly more data than it receives from a server). User behavior monitoring may help to detect abnormal patterns of activity.[37]

References

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  3. Levene, B, et al. (2017, May 03). Kazuar: Multiplatform Espionage Backdoor with API Access. Retrieved July 17, 2018.
  4. F-Secure Labs. (2015, April 22). CozyDuke: Malware Analysis. Retrieved December 10, 2015.
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  11. FireEye Threat Intelligence. (2015, December 1). China-based Cyber Threat Group Uses Dropbox for Malware Communications and Targets Hong Kong Media Outlets. Retrieved December 4, 2015.
  12. ESET. (2016, August 24). First Twitter-controlled Android botnet discovered. Retrieved December 22, 2016.
  13. Hayashi, K. (2017, November 28). UBoatRAT Navigates East Asia. Retrieved January 12, 2018.
  14. Schwarz, D., Sopko J. (2018, March 08). Donot Team Leverages New Modular Malware Framework in South Asia. Retrieved June 11, 2018.
  15. Mandiant. (n.d.). Appendix C (Digital) - The Malware Arsenal. Retrieved July 18, 2016.
  16. Axel F, Pierre T. (2017, October 16). Leviathan: Espionage actor spearphishes maritime and defense targets. Retrieved February 15, 2018.
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  18. Lee, B., Falcone, R. (2019, January 18). DarkHydrus delivers new Trojan that can use Google Drive for C2 communications. Retrieved April 17, 2019.
  19. Gannon, M. (2019, February 11). With Upgrades in Delivery and Support Infrastructure, Revenge RAT Malware is a Bigger Threat. Retrieved May 1, 2019.
  1. Faou, M. and Dumont R.. (2019, May 29). A dive into Turla PowerShell usage. Retrieved June 14, 2019.
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