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T1481.002 Bidirectional Communication

Adversaries may use an existing, legitimate external Web service channel as a means for sending commands to and receiving output from a compromised system. 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. This is 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.

Item Value
ID T1481.002
Sub-techniques T1481.001, T1481.002, T1481.003
Tactics TA0037
Platforms Android, iOS
Version 1.1
Created 06 April 2022
Last Modified 16 March 2023

Procedure Examples

ID Name Description
S0655 BusyGasper BusyGasper can be controlled via IRC using servers.2
S0485 Mandrake Mandrake has used Firebase for C2.3
S0545 TERRACOTTA TERRACOTTA has used Firebase for C2 communication.1


ID Data Source Data Component
DS0041 Application Vetting Network Communication
DS0029 Network Traffic Network Connection Creation